feature article – Page 4 – The Native Plant Gardener

A Marsh Marigold by Any Other Name

Posted on November 2, 2022November 2, 2022 by ridgetownrick

William Shakespeare, in his play Romeo and Juliet, wrote “A rose by any other name would smell as sweet”. So why does it matter what we call it, then? And why do people like me sometimes get so frustrated when folks use common names instead of the scientific names for plants? In today’s article, I want to explore the benefits, and in some cases the frustrations, of using scientific names for our native plants instead of (or, at least, in addition to) the common names.

“Latin is a dead language, so why do we use it for plants?” The simple answer – tradition. However, every plant has but one “scientific name”, or scientific binomial, that is unique to that plant, whereas it may have 2 or 3 (and, in some cases, dozens of) common names. What’s worse, the same common name is often used for many different plants.

For instance, as I pointed out in last month’s blog post, when I talk about Black-eyed Susans, I could be referring to Rudbeckia hirta (an annual/biennial) or Rudbeckia fulgida (a perennial, also known as Orange Coneflower) or even Rudbeckia triloba (a perennial also known as Brown eyed Susan) depending on what part of the country you are in.

Both Asclepias hirtella and A. viridiflora are called Green Milkweed, though in some locations A. hirtella is known as Tall Green Milkweed – which is what I call it to help me keep the two separate in my mind.

Is Wild Columbine the same plant as Eastern Red Columbine? Yes, it is. It is also known as Cluckies in some parts. In other areas they call it Jack-in-trousers. But it is also known as Rock Lily. All these common names, yet it has only one scientific name – Aquilegia canadensis.

Caltha palustris – commonly called Marsh Marigold – has at least 30 distinct common names that I have been able to find, and a whole lot more if you count names that are similar but just spelled differently. Some of these names are just plain weird, if you ask me. Here are just a few of them (in alphabetic order): Boots, Brave Bassinets, Bull Flower, Cow Lily, Cowslip, Crazy Beth, Crowfoot, Drunkards, Goldes, Gools, Horse Blob, King’s Cup, Mare Blob, Marybuds, May Blob, Meadow Buttercup, Meadow Cowslip, Meadow Gowan, Meadow-bright, Mireblob, Publican’s Cloak, Publicans-and-sinners, Soldier’s Buttons, Water Boots, Water Buttercup, Water Cowslip, Water Dragon, Water Goggles, Water Gowan, Yellow Gowan. And that’s just a partial list. Horse Blob??? Crazy Beth??? Where do they come up with these names?

And then there is Goat’s Rue – a name used for both the rare native Tephrosia virginiana which is considered critically imperilled in Ontario, and the non-native Galega officinalis, considered an invasive species in Pennsylvania. Knowing the scientific binomial can prevent a lot of confusion. It can also keep you from buying the wrong plant.

But why is it called a binomial? Because the name consists of 2 parts. The first part is the genus (plural genera) – which always starts with a capital letter. The families of plants (e.g. Asteraceae – Aster Family; Laminaceae – mint family; Liliaceae – lily family; Ranunculus – Buttercup family, etc.) are subdivided into genera – which are groupings of similar plants within that family.

The second part of the binomial is the species name or “specific epithet”, which always starts with a lower-case letter and represents closely related plants within a genus. Example: Asclepias tuberosa. Asclepias tells us this plant is in the genus that contains the milkweeds, and tuberosa tells us which species of milkweed plant it is – in this case Butterfly Milkweed. Note that, by tradition, foreign words (including Latin) are always written in italics.

A tip for trying to remember the Latin names (though even this is not consistent) is that you can often figure out how the species name ends (is it with an -a, a -um or something else?) by looking at the genus. Latin has feminine, masculine and neuter (neutral) words that may or may not have different endings. Names that end in “-us” are masculine. Words ending in “-a” are feminine, and those ending in “-um” are neutral. So the species name should match the gender of the genus.

For instance, Purple Coneflower is Echinacea purpurea (feminine) and Sweet Joe Pyeweed is Eutrochium purpureum (neutral) while the South American native Morning Glory was called Convolvulus purpureus (masculine) until they changed the Genus to the feminine Ipomoea and had to change the species to purpurea to match the gender.

But just to make sure you don’t find this straight forward and starting to make sense, a number of scientific names for plants are based on Greek and not Latin, which have different endings for masculine, feminine and neutral words. And these are less consistent than their Latin counterparts. For example, the feminine ending –a (Monarda) is the same as the Latin, but –ago (Solidago), –e (Anemone), and –is (Anaphalis) are also feminine endings in Greek. Hence you get Solidago juncea, Anemone virginiana, and Anaphalis margaritacaea.

And though most of the Latin and Greek names are derived from some characteristic of the plant, such as sempervirens – which means “evergreen”, or racemosa – which indicates the flowers are in racemes, many plants are named after prominent botanists, such as Gentiana andrewsii (bottle gentian – named for Henry C. Andrews, 1794-1830) or Geranium bicknellii (Bicknell’s geranium – named for Eugene P. Bicknell, 1859-1925). The –ii at the end indicates the plant is named after a male. Rosa banksiae, the Lady Banks’s rose, on the other hand, is named after Dorothea Lady Banks, the wife of Joseph Banks (1743-1820) who sailed with James Cook on the Endeavour. But is the feminine usage because the person it’s named after is female? Or is it simply to match the feminine Rosa of the genus? The –ae on the end of banksiae is the plural ending of the Latin –a, though why it is plural is beyond me.

Confused yet? As they say on those cheap TV commercials – but wait, there’s more!

“Sometimes I see more than just the two names, and sometimes there is ‘cv’, ‘var.’ or ‘subsp.’ inserted between the names. What does that mean?” The cv is short for cultivated variety, often shortened to cultivar, which is a plant that has been selected for certain characteristics, but normally doesn’t produce true-to-seed. The var. is the abbreviation for variety (varietas in Latin). Botanists will sometimes see that one species has enough genetic variation to separate the plants, but they agree the two plants are still the same species as they can still crossbreed and produce viable offspring – which is one of the defining characteristics of a species. Subsp. is the abbreviation for subspecies – a similar condition. Both are used, but var. is more common in plants, and subsp. is more common with animals. (I don’t make the rules, I just try to follow them as best I can.)

Are the scientific names carved in stone? I wish! As our science allows us to better understand the genetics of plants, we have been realizing that early botanists didn’t always get it right. Sometimes a plant looks very much like another, so much so that early botanists were convinced they were different species in the same genus. But genetic testing is showing this to not be the case for several species.

Sometimes they simply move the plant to another genus, as with barren strawberry – formerly Waldsteinia fragarioides, now Geum fragarioides. In some cases, even the species name gets changed, too, as with white snakeroot – formerly Eupatorium rugosum, now Ageratina altissima.

Sometimes they have to come up with a brand new genus, as they have done for the asters of North America. Aster is now reserved for “old world” asters, as opposed to North American asters. On top of that, we now divide the North American asters into 11 different genera.

Then there is the Upland White Aster, which for many years was known as Aster ptarmicoides – one look at it will tell you that it is obviously an aster. Then an observant botanist realized that it hybridized with a couple of species of goldenrod, but never with an aster, and they discovered that it was a well disguised goldenrod – so the name was changed to Solidago ptarmicoides or Upland White Goldenrod.

And just to make things a bit more challenging, unfortunately not all botanists agree on the name that should be applied to a particular plant, so when you look up a plant online, you may find that the Database of Vascular Plants of Canada, or VASCAN for short calls it one thing, while the Royal Botanic Gardens at Kew calls it something else in their Plants of the World Online. Likewise, iNaturalist claims to follow the Catalogue of Life, but I have found a number of exceptions there, too. Just so you know, as a Canadian I choose to follow the VASCAN nomenclature.

Pronunciation of all these names is another thing altogether. I found a fairly good online pronunciation resource at https://baygardens.tripod.com/botlatin.html, but here are a couple of great books on Latin for gardeners that I have on my bookshelf and refer to quite frequently.

Using the scientific name for plants can help because, even if we don’t agree WHICH scientific name is the right one, no two plants will have the same scientific name, whereas one common name can apply to multiple plants. And this can help you get the plant you THINK you’re buying.

Hopefully you found this little tutorial useful. Your feedback is always appreciated.

As always, happy native plant gardening.

Time for a Black Eye

Posted on September 30, 2022September 30, 2022 by ridgetownrick

Which Black Eyed Susan is Which?

Harris Checkerspot butterfly on Rudbeckia hirta (Black Eyed Susan).

Do you want a black eye? Black eyed Susan, that is. Or is that a brown eyed Susan? The other day someone asked me how to differentiate this group of plants that, at first glance, look so much alike. Today, I will attempt to tackle that question here.

Those who know me know that I get really frustrated with common names for plants. Depending on where you live, the name black eyed Susan is used for a number of different yellow flowers with a dark center. The most common ones, at least here in southern Ontario, are Rudbeckia hirta (which I call black eyed Susan), Rudbeckia triloba (brown eyed Susan) and Rudbeckia fulgida (orange coneflower). However, these plants also come with a lot of other names that you might know them by, just to keep things confusing. For example:

Rudbeckia hirta (Black Eyed Susan) is also called Bristly Coneflower, Brown Betty, Brown-eyed Susan, Common Black-eyed Susan, English Bull’s Eye, Gloriosa Daisy, Golden Jerusalem, Poor-land Daisy, Yellow Daisy and Yellow Ox-eye Daisy.

Rudbeckia fulgida (Orange Coneflower) is also known as Black Eyed Susan, Brilliant Coneflower, Brown Eyed Susan, Orange Rudbeckia, Perennial Black-eyed Susan, Showy Black-eyed Susan and Showy Coneflower.

Rudbeckia triloba (Brown Eyed Susan) also goes by the names Thin-leaved Coneflower, Three-lobed Coneflower and Three-lobed Rudbeckia.

But it’s not just the names that can be confusing. To the uninitiated, these 3 flowers look very similar. And the descriptions you read about them don’t always help, simply because there can be so much variability within each species that, until you get to know the plants, the descriptions seem to overlap.

Rudbeckia hirta – Black Eyed Susan

Let’s start with Rudbeckia hirta, Black Eyed Susan. For me, the main differentiating characteristic is the fuzzy leaves and stems – fuzzy enough that the leaves actually appear to be a lighter colour than the other Rudbeckias. But fuzziness is a relative characteristic as all 3 have a certain amount of hairiness to the leaves and stems. Once you see the leaves side by side, however, you will easily tell them apart in the future (most of the time).

R. hirta leaves tend to be strap-like and, on average, tend to be longer and narrower than the other two. And they are ALMOST ALWAYS very hairy.

Rudbeckia hirta leaves tend to be more strap-like and are usually paler than the other two.

This plant is quite variable in its nature, though. It may be an annual, a biennial or even a short-lived perennial in some cases. And the genetic variability within the species can result in individuals with different petal shapes, different leaf shapes and sizes, and even a range of hairiness of the stem and leaves. But on average, the leaves and stems have a pale fuzzy appearance. If it’s late in the season, they also tend to die off in early fall (at least the annual and biennial ones do) whereas R. fulgida and R. triloba tend to stay green well into the late fall, even after the flowers have finished.

Rudbeckia hirta does well in full sun to part shade in just about any dry to moist, reasonably fertile, well-drained soil. This plant will grow to a little over 3’ tall and in the wild is found in fields, open woods and along roadsides.

R. hirta Native Range:

*Rudbeckia hirta* is found throughout the region, though it may be spotty or even non-existent depending on soil, microclimate and other characteristics.

Rudbeckia fulgida – Orange Coneflower

This shorter statured plant is an extremely popular garden perennial, mainly because once it starts blooming it tends to put on a non-stop show for months. In most years in my southwestern Ontario garden, it starts to flower in late June or early July and keeps going till frost – sometimes as late as November, though after the drought we had here this year, they’ve pretty much finished blooming in mid-September.

A very common cultivar (or nativar, if you prefer) is Goldsturm. There are also even shorter cultivars, usually with the word “Little” somewhere in the name. The straight species typically grows 2-3’ tall, as does the Goldsturm variety. Most of the others are only 1-2’ tall. I have yet to find a definitive article on how Goldsturm is different from the true species. If you have the scoop on this, please let me know.

The leaves on R. fulgida tend to be much wider than on R. hirta and usually have fairly large serrations along the edges, especially on the lower leaves. As you can see in the photos, though, they may have no serrations at all. And though they may feel somewhat rough and hairy, they are not nearly as hairy (on average) as R. hirta.

The lower leaves, especially, are deeply serrated on *Rudbeckia fulgida.*

One thing is for sure – R. fulgida produces a much denser mass of colour than R. hirta, and for a much longer period of time, though R. hirta always starts flowering a couple of weeks before this one does. It’s not that fussy about where it grows – it will do well in moist to dry, sandy to clay soils in full sun to part shade. I have a patch that is in full, light shade and it is doing just fine.

*Rudbeckia fulgida* typically provides a nice, solid mass of showy flowers in the garden.

R. fulgida Native Range:

*Rudbeckia fulgida* is a more southerly plant, barely making it into Ontario.

Rubeckia triloba – Brown Eyed Susan

Not native in Ontario, this nonetheless very popular short-lived (typically 2-3 years) perennial is the tallest of the 3 plants discussed here – in ideal conditions (full sun, moist loamy soil) it can get upwards of 5’ in height, though one writer indicated his plant hit 8’ tall!

The easiest way to differentiate R. triloba from the other two is to take a look at the leaves near the base of the plant. These are what give this plant its specific epithet (or species name) – triloba. The lower leaves have 3 (occasionally 2) lobes, as seen in the accompanying photo. The upper leaves look quite similar to R. fulgida, with the same variability in hairiness and serrations.

The 3 lobed basal leaf that gives *Rudbeckia triloba* it’s species name.

The other telltale difference is that R. triloba also tends to have a fairly reddish stem – sometimes it may be a deep solid burgundy colour, but on other plants it may be more of a striped stem. The stems are almost always fairly hairy.

*Rudbeckia triloba* stems tend to be reddish, but even that is variable.

*R. triloba* petals tend to be a bit wider than the narrow *R. fulgida.*

Rudbeckia triloba is probably the fussiest of the 3 for growing conditions, but it is still quite versatile. It prefers moist to mesic loamy or sandy-loam soils, though some clay is tolerated. Like Rudbeckia fulgida, it blooms from July to first frost.

R. triloba Native Range:

*Rudbeckia triloba* range matches fairly closely with *R. fulgida*, but historical records indicate is was not known in Ontario before Europeans arrived.

If you have a native plant gardening related topic that you would like to know more about, let me know and I will add it to my growing list (pun intended). If it’s something I get multiple requests for, or is simply something that strikes my fancy, it will surely move up the priority list.

Happy Native Plant Gardening.

How Does Your Garden Grow?

Posted on September 1, 2022September 1, 2022 by ridgetownrick

(Source: *William Wallace Denslow’s rendition of the poem, 1901,* *https://en.wikipedia.org/wiki/Mary,_Mary,_Quite_Contrary*)

Many of is remember the old nursery rhyme Mary, Mary, quite contrary, How does your garden grow?

Although historians disagree on the possible political meanings behind this 18th century English nursery rhyme, I wish to use this question “How does your garden grow” to explore the various approaches to gardening with native plants.

Naturalized Gardens

We all garden with native plants for different reasons. Some gardeners attempt to create a more ‘natural’ habitat for insects, birds and other wildlife on their property and design their gardens around ecological principles. These gardens may often appear messy to the uninitiated, and are often more suited to larger properties and/or rural properties. Otherwise, they may fall afoul of local city ordinances that were often developed in the 60s and 70s when uniform, mowed grass was seen as desirable and when bylaws were enacted to prevent homeowners from simply neglecting their yards.

Spring ephemerals, such as trilliums and woodland phlox, in a naturalized garden.

Formal Gardens

At the other end of the spectrum are those who have taken the formal flower beds of European ancestry and simply replaced some or all of the non-native species with native ones. These gardens are often geared to human sensibilities and historical tastes. The fact they attract more insect life than gardens comprised solely of exotic species is more a lucky side effect than a planned outcome.

Formal beds with natives replacing exotic species can be just as beautiful. (images are of my garden in southwestern Ontario)

And then there is the whole gamut of garden design options between the two extremes.

Semi Formal

The Importance of Native Plants

I would be willing to bet that most of us grow native plants, at least in part, for the benefit they provide to our wildlife. To that end, ANY incorporation of native species is likely to be better than none at all. However, Doug Tallamy’s research in the US has shown that the successful fledging of a nest of Carolina chickadees requires at least 70% native species within their foraging range. And anything below 30% will likely result in the complete loss of the nest of babies. This is because non-native plants do not host the diversity and numbers of insects necessary to feed a nestful of baby birds. Although Tallamy’s research looked at just the one bird species, it is probably safe to assume that it is similar for other bird species, since most birds – even the seed eaters – raise their young on a diet of caterpillars, spiders and other soft-bodied insects. (If you haven’t read them yet, I highly recommend Tallamy’s books Bringing Nature Home and Nature’s Best Hope.)

If you’re reading this article, then you are most likely already aware of the importance of native plants. But how many others are? You would hope that anyone who gardens would have an appreciation for nature. And even though native plant gardening is the fastest growing (pun intended) sector of horticulture in North America, a lot of gardeners are still unaware of its virtues.

Take for example a recent trip I made to a scenic small town in southern Ontario, noted for its active horticulture society and its beautiful gardens. In a 10 block walk, I saw one yard containing a native species in its flower beds. Note the singular. And technically, the town was a bit far north to actually claim Rudbeckia fulgida (orange coneflower) as a native species. (To be fair, in another part of town I did find a couple of gardens that were primarily natives, but that was it.) We have a long way to go to educate other gardeners on the benefits (and beauty) that adding native plants can provide.

Where Do I Start?

But if we want to grow natives, which way is best? Well, that depends. My own gardens fall somewhere closer to the ‘formal flower beds’ end of the spectrum, designed to be showcases of what we can do with native species. Though with the passage of time they are slowly moving away from that as I let plants spread and self-seed, often where they want.

I came at my gardens from the perspective of an educator wanting to show folks that native plants can be just as beautiful, and usually a lot more beneficial, than non-native species. My aim has been to bring those who knew only the Edwardian style of manicured gardens full of exotic plants into the world of native plant gardening.

In the municipality of Chatham-Kent (in southwestern Ontario) we recently held our second annual native plants garden tour. (Thanks and a shout out to Mike Smith with ReLeaf Chatham-Kent for spearheading this). This year, gardens once again ranged from restored acreages to small butterfly gardens, from gardens planted in a cul-de-sac island by a committee to a half acre of formal flower beds of only native species set in a private garden. Some have natives mixed with non-natives while other “purists” try to plant only what was found locally (or nearby) before Europeans arrived. Some have been growing natives for a decade or more; for others this is their first venture into growing indigenous species.

If you’re reading this, then at least you are interested in growing native plants. And if you haven’t started yet, don’t worry – it’s easy. But it will take some thought and some homework. First you need to decide WHY you want to grow native plants. That will help you choose the style that will work best for you.

Do you have already established garden beds? Perhaps you just bought your first house and have inherited a lot of non-native and possibly some invasive species. Do you like the layout of the gardens, or do you have a vision of your own? Start by identifying the non-natives that are invasive or otherwise problematic and digging those out. There are lots of on-line resources to help with this. Just Google “invasive plants” and your state or province. Or look up a document called “Plant me Instead”. Visit some native plant nurseries (this web site has a map of all the native plant sources in North America that I’ve been able to find), attend a webinar by your local naturalist organization, join a native plant gardening Facebook group (if you haven’t already). These are all great ways to learn about what is or isn’t native and to help you decide what to plant where.

Giant swallowtail butterfly caterpillar feeds on hop tree leaves while it hides in plain sight looking like bird poop.

Do you have a large, blank slate? This can sometimes be very intimidating. And unless you’ve got very deep pockets, you probably won’t want to convert the whole yard at once. But don’t just jump in with both feet. Even if you’ve been growing natives for a while, if this is a new location then watch the sun – where is it sunny the longest? Where is the shade? What is your soil type? (If you don’t know, get it tested. Your local department of Agriculture will be able to tell you where, and how much it will cost. Or you can buy a soil test kit from a number of sources, and though these won’t be quite as accurate as an official laboratory test, they may be good enough to get you started.) Is the soil dry? Are there low areas that might stay wet for part of the year or after a heavy rain? If all else fails, there are lots of knowledgeable folks living probably not far from you, and some of these will be happy to come and advise you (for a fee).

Water is Important,Too!

If your intention is to attract birds, dragonflies and other creatures, try to add moving water – either a small waterfalls or simply a fountain. The sound of running water will attract birds from far and wide, and you’ll see a huge increase in insects like dragonflies and damselflies, all of which will come to bathe and to drink.

Frogs galore in this small, natural looking pond.

There is no prescription for native plant gardening. We all grow what we grow for our own reasons. One thing everybody growing native plants seems to agree on, though – we wonder why everyone isn’t on board yet.

Happy native plant gardening.

Invasive Species, Weeds, Nativars and Other Terms of Confusion

Posted on July 30, 2022July 30, 2022 by ridgetownrick

The native plant gardening world is full of terminology that those gardening with non-natives have seldom had to consider. In this month’s article, I hope to shed some light on what some of these terms actually mean so that you can speak confidently and knowledgeably with garden center staff and fellow gardeners.

Native vs Naturalized

I started my journey into native plant gardening with the purchase of a package of “wildflower” seeds. When I recognized California poppies, bachelor’s buttons, and a few others I knew were not from these parts, I became confused. That’s when I discovered that wildflower is NOT the same as native. After a little more research, and a broken heart, I discovered that many of the wild plants I grew up loving in the fields and forests were actually European, Asian or other non-natives that had escaped from gardens over the past couple of hundred years and not the cherished native plants I thought they were. So what IS a native plant?

In its simplest terms, the general consensus used by many but not all, is that any plants growing in an area before the European settlers arrived are considered native. These are the plants that evolved here and developed ecological relationships with the insects and birds and other animals as well as with the surrounding plants. These relationships developed over thousands of years. Europeans, as well as those from other parts of the world, came to this continent and brought plants they were used to using and or seeing, and all of these plants are considered to be non-native. Yes, plants migrate, but they do so very slowly and local ecosystems typically have time to react to any newcomers. The sheer volume and strangeness of the plants that were introduced by settlers really disrupted these natural changes. And, yes, changing climate is likely to allow plants not previously growing here to survive, but the rate of change will be nothing like the speed of putting a packet of seed in a truck in Arkansas and spreading in your southern Ontario garden a week later.

Click on any image to view a larger version.

Monarch butterfly laying eggs on swamp milkweed (Asclepias incarnata)

I don’t know when the currently accepted definition was proposed or by whom, and it leaves many unanswered questions, such as: should plants that were brought here by First Nations peoples (e.g. pawpaw – Asimina triloba) also be considered native? By keeping the definition simple, i.e. is it pre-European, the answer is also simple: yes. (There have been many long, philosophical discussions on the topic in many native plant forums. But I like to keep things as simple so this is the definition I use.)

So what, then, is a naturalized plant? Naturalized simply means that that particular non-native species can exist in the wild without human intervention. Many of my favourite childhood wildflowers, like mullein (Verbascum Thapsus) and common chicory (Cichorium intybus), and even dandelions (Taraxacum officinale) fall into this category. Though many non-natives have adapted well to the wild, many, like zinnias (Zinnia elegans), petunias (Petunia spp.) and many of our vegetable crops, like bell peppers (Capsicum annuum), cannot survive long in our region without human intervention. Some, on the other hand, have adapted so well they are considered invasive.

Invasive vs Aggressive

We often hear about invasive species, and sometimes (incorrectly) an overly aggressive native plant like Jerusalem artichoke (Helianthus tuberosus), or Canada goldenrod (Solidago canadensis) are called invasive. However, the term invasive species is reserved for non-native plants that are so prolific, either because they self seed, spread vegetatively, and/or produce toxins to inhibit the growth of any competition, that they spread unchecked and have a large negative impact on the natural ecological balance of an area. Note that not all non-native species are invasive, but those that are can have devastating effects on local flora and fauna.

I plant my very aggressive Jerusalem artichoke in a large barrel sunk in the ground. This way they can’t spread to the rest of my yard.

They way I wrapped my head around the terminology is with an analogy: If our military forces came into a major city and started roughing up and arresting people, we’d say they are being aggressive, but if a foreign army did this, we’d say they were invading. The domestic army can’t invade because it’s already here. Same for plants – Canada goldenrod can’t be invasive because it belongs here. But a plant from another part of North America that was never here before CAN be considered invasive. For instance, cup plant (Silphium perfoliatum) was never native in New York state but it is a very aggressive spreader and is therefore considered an invasive species there^{1, 2} (and it is illegal to sell or grow it for sale in that state).

Weeds

Weed is another term that has some confusion surrounding it (I’m not talking about the weed your brother-in-law smokes, either). Weeds may be non-native OR native plants. We’re all familiar with dandelions – some consider it a weed while others do not. This Eurasian-native species was brought by European settlers as early as the 1600s as a food and medicine plant³. Plants like Canada thistle (despite its name, it, too, comes from Eurasia) were brought for the same reasons, or because they were familiar flower garden plants “back home”. These, and many more, have become ubiquitous throughout North America. But the term weed is actually an agricultural term and describes any plant that has a negative economic impact on agricultural (food) production. In our gardens, is simply a plant that is unwanted where it is growing and in traditional gardening, these often happen to be native species, though not always.

Erigeron canadensis (Horseweed, or Canada Fleabane) is a prime example of a native plant that is considered a serious weed in agricultural crops, especially since it developed resistance to glyphosate (the major weed-killing ingredient in Roundup) and to acetolactate synthase (ALS) herbicides. Milkweed, especially Asclepias syriaca or common milkweed, was long considered a noxious weed – a special category for the really nasty ones – and was eliminated from farm fields whenever it was encountered. Livestock won’t eat it, its rapidly spreading rhizomes enables it to take over large areas of a field out-competing the farm crops, and it had huge impacts on the farmer’s bottom line. We now know that it is also essential for the survival of the monarch butterfly, and as a result many jurisdictions have removed it from their noxious weeds lists.

Click any image to view larger version.

https://www.canr.msu.edu/news/early_management_horseweed_control_in_soybeans_is_important

Essentially, a weed is simply a plant growing where you don’t want it. In my all-native-plants garden, for instance, I consider squirrel-planted tulips and star of Bethlehem plants to be weeds. (I even refer to my hosta bed under a large maple tree in my front yard as my “weed garden”, and one day it will get “weeded” and native plants put in).

Cultivars and Nativars

Some other terms in native plant gardening also bring some confusion, especially to those just starting out. For instance, what’s the deal with cultivars and what is a nativar? The term cultivar is simply an abbreviation for the phrase “cultivated variety”. Nativar is a newer term that has come with the surging interest in native plant gardening and is simply a combination of two terms, native and cultivar.

When many of us start to grow native plants in our gardens, we bring with us a history of growing non-natives. We, therefore, often look to the exotics for unusual colours or forms. I was no different in this regard – I was in in my 50s, with close to 40 years gardening experience, when I discovered native plant gardening. When I saw a cardinal flower (Lobelia cardinalis) with a deep burgundy colour, a swamp milkweed (Asclepias incarnata) with a pure white flower, or a bloodroot (Sanguinaria canadensis) with a “double” flower, I was amazed and wanted it in my garden. Most often these plants are simply natural mutations that horticulturalists have latched onto and have cloned for resale. Some will breed true to the new form, but some are one-off freaks of nature whose seeds, if they even produce any, will revert to the original. Others are the result of selective breeding. And because the horticulture trade is, for the most part, driven by profit, some growers will select for unusual colours or forms to meet the demand for exotic plants.

You can usually spot a plant in the garden center that is a cultivar because the tradition is to include the commercial name (either in quotation marks or not) after the scientific name, such as Aclepias incarnata “Ice Ballet” – note that the scientific name is in italics but the cultivar name is not. The use of var. (for variety, or in Latin, varietas) in the name, as in Cercis canadensis var. alba, is supposed to be used for naturally occurring varieties that have been selected for certain characteristics (in this case, a white version of redbud) rather than for plants that have been specifically bred for the trait. Unfortunately, there is not a lot of consistency in how these terms are used in the trade. (See article #4 in the reference list below for some more detailed explanations of these and other related terms.)

Click on any image to view larger version.

White swamp milkweed (Asclepias incarnata)

But as intriguing as some of these unusual variations are, recent research is showing that not all cultivars/nativars are equally valuable to the insects that depend on them⁵. Nutritional values can vary because the genetics that produce a desirable feature may be connected to those that impact nutritional value (similar to the genetics that make a German shepherd dog look the way it does also makes it susceptible to hip dysplasia). For instance, many of the double flowered nativars either do not produce nectar or pollen – the extra petals in double flowered species is often a mutation where the stamens in a flower are replaced by petals – and are often sterile, while others may be unpalatable to the insects that need it to survive. As the interest in native gardening grows so, apparently, does our interest in nativars and ongoing research is needed to determine which varieties are just as good for the insects as the originals.

Summary

You should now be able to confidently explain that, no, Canada goldenrod is NOT invasive, but garlic mustard is (and why). You should also be able to explain to your neighbour why those tulips in your lawn are actually weeds, why the milkweed in your front garden isn’t, and what the difference is. And finally, when shopping for some new plants, if you see a non-Latin name pinned to the end of the scientific name on the plant tag, you’ll know this is (most likely) not a pure native species and, as such, may not have the same value to the insects and other critters that need it to survive.

Happy native-plant gardening.

https://nyis.info/wp-content/uploads/2018/01/d8be1_Silphium.perforatum.NYS_.pdf

https://www.dec.ny.gov/docs/lands_forests_pdf/isprohibitedplants2.pdf

https://www.fbn.com/en-ca/community/blog/where-did-all-of-these-weeds-come-from

https://www.mapleleavesforever.ca/cultivar-variety-or-nativar-as-it-relates-to-our-native-maple-species/

https://piedmontmastergardeners.org/article/native-species-or-cultivars-of-native-plants-does-it-matter/

2b or Not 2b – The Story Behind Plant Hardiness Zones

Posted on June 29, 2022June 29, 2022 by ridgetownrick

Most gardeners are familiar with the Plant Hardiness Zone (PHZ) maps that are found in many seed catalogues and garden centers, and with the paired numbering system (2a, 2b, 3a, 3b) etc. found on plant labels. But what do these numbers really mean? How did they come about? And are they really relevant for native plant gardeners?

The earliest PHZs were delineated in the 1920s by the Arnold Arboretum at Harvard University. In the 1960s, the US Department of Agriculture (USDA) devised their own set of PHZs using different criteria resulting in two different maps. However, the Arnold Arboretum map remained the standard until 1990, when the USDA, in conjunction with the US National Arboretum, and using data from thousands of weather stations, created the maps we now see. These maps are based on the average minimum winter temperatures. Each zone is marked at 10°F intervals, with the division between a and b at the 5° interval (e.g. zone 6a has an average winter minimum temperature of -10 to -5°F, 6b is -5 to 0°F). The logic behind this system is that plants have a cold threshold they won’t survive beyond.

USDA PHZ: https://planthardiness.ars.usda.gov

Unfortunately, these zones are a bit too simplified because plants are affected by more than just minimum winter temperatures, especially the further south you go. In snowbelt areas, for example, temperatures may drop well below freezing, but a deep blanket of snow can keep the plants safe. Basing the plant hardiness zone on minimum temperature doesn’t always work. Regardless of what minimum winter temperatures the plants will succumb to, some plants also tolerate heat much better than others. So the American Horticultural Society (AHS) devised their Plant Heat Zones based on the number of days the temperature went above 30°C (86°F), but their methodology created some problems as well. For instance, some plants can take lots of heat in the daytime but need cooler nights to recover and so just counting the number of days the temperature is above 30°C doesn’t really work. Also, plants like hostas love the heat, but they need cool winter temperature in order to go dormant so that they can start to grow again in the spring.

AHS Heat Zone Map: https://ucanr.edu/blogs/dirt//blogfiles/37486_original.jpg

If you’ve ever looked at the Canadian PHZ map, you’ve perhaps noticed that it doesn’t quite align with the USDA map. This is because the Canadian map is likely more properly called a Plant Suitability Map (though it still goes by the Plant Hardiness Zone moniker).

Canadian PHZ: http://planthardiness.gc.ca/?m=1

Originally developed in the 1960s, it uses a wide range of variables, not just minimum and or maximum temperature. The variables are: monthly mean of the daily minimum temperatures (°C) of the coldest month; mean frost free period above 0°C in days; amount of rainfall from June to November, inclusive; monthly mean of the daily maximum temperatures (°C) of the warmest month; winter factor expressed in terms of (0°C – X₁)Rjan where Rjan represents the rainfall in January expressed in mm; mean maximum snow depth; and maximum wind gust in (km/hr) in 30 years; and it incorporates them into a complex mathematical formula. You can read more about the formula and how it works here.

The original formula is the result of statistical analysis of the survival of 174 different trees and shrubs from 108 locations across the country (McKenney and Campbell, 2002, Getting into the Zone – what does Canada’s new plant hardiness zones map really mean? Frontline Technical Note #103 – see link to the paper at the end of this article). The newest version of the map was generated using computer models and interpolating climate data generated at more than 3400 locations across the country.

Which is the best (i.e. most accurate and reliable) system? Being Canadian, I’m probably biased. But it would seem that the more thorough and complex Canadian system is likely the more accurate. The challenge is getting everyone to agree on one system. Most garden centers use the USDA system, probably because it has been around for a long time and the plant labels they purchase (likely from US sources even here in Canada) use that system.

Surprisingly, even though the American and Canadian calculations are very different, in the southern Great Lakes region the results are close enough to be compatible for most of the plants – although some sources I’ve seen suggest that the Canadian and American systems may differ by as much as one complete zone in some locations. Also, both the US and Canada have been widely mapped using the USDA PHZ criteria, but I’ve not found any maps yet where the US has been mapped using the Canadian system. So, it doesn’t look like we’ll have a unified system any time soon.

USDA Plant Hardiness Zone Map (North America): http://www.perennials.com/content/plant-hardiness-zone-maps/

But even with all the variables used in the Canadian maps, there are so many things that will affect the plant’s survivability that just cannot be easily mapped. Extreme weather events, microclimates caused by built structures, local topography, even mulching and watering, can have a significant impact on plant survival.

When it comes to native plants, though, a lot of research is still needed to verify the zones they will survive. Accurate range maps overlaid on PHZ maps will go a long way to answer these questions, but native range of so many of our native plants have not been mapped with any level of detail.

Then there is the question of whether we should even worry about what areas our native plants are capable of growing in – if the idea is to keep native plants in their native range, the more important issue is to figure out where the plants actually grew before we started putting them in our gardens everywhere. This way our native plant gardening efforts will better serve the insects and animals the plants evolved with, and not just our personal aesthetic.

Until next time, happy native plant gardening.

Rick

Other Resources:

Getting Into the Zone Article by Dan McKenney and Kathy Campbell PDF

Can I have continuous bloom in my native plant garden? Part 2

Posted on May 29, 2022May 29, 2022 by ridgetownrick

In my previous article, I discussed continuous blooms for the shady garden as a response to someone’s query, so in this piece I will look at plants for the “average” garden – moist to dry soils, full sun to part shade. (Unless noted otherwise, all images are from my southwestern Ontario garden.)

Part 2 – The Less Shady Yard

When I started growing native plants in my garden, I was disappointed that for much of the early part of the growing season there wasn’t much colour in my garden. Once the spring ephemerals like trilliums and bloodroot were finished in the shade garden, nothing much happened till July. It seemed to me that Mother Nature only offered native colour in the summer and fall. So that’s when I started to dig deeper into the native plant literature. It didn’t take me long to start finding the missing pieces. In this article, I will offer up some native plant choices that will help you provide colour in your garden, and food for the local pollinators, from spring right through till the snow comes.

April/May/June – May is when some of my favourite native plants start to bloom. Geum triflorum (prairie smoke) starts to blossom in early May and continues well into June. It has an unusual pink blossom, but it’s the wispy pink seed heads that give this plant its name and is the real attraction in the garden. I have seen fields of prairie smoke in Manitoba, and it does look like smoke laying close to the ground. Planted in swaths as a foreground plant, it can provide quite a show. Another interesting foreground/rock garden plant is Antennaria neglecta (field pussytoes), with its white tufts of flowers that give it its common name. Note that Antennaria is a host plant for the American Lady butterfly.

We have a couple of very low-growing buttercups that bloom very early in the spring, too. Ranunculus rhomboideus (prairie buttercup) produces yellow flowers in late April – often one of the very first flowers to blossom in my garden – and R. fascicularis (early buttercup) starts to flower about 2-3 weeks later. Prairie buttercup keeps flowering for several weeks, too.

Zizia aurea (golden Alexander) blooms from early/mid May for about a month with wild-carrot like foliage and bright yellow flowers. This is a host pant for the black swallowtail butterfly. The first time I grew one of these, I found 7 black swallowtail caterpillars on the single plant. (I have since planted many more!). I find they do self seed quite a bit, but the heavy seeds do not seem to land far from the parent plant.

The hummingbirds love my Aquilegia canadensis (wild columbine). In my southern Ontario garden, it usually starts blossoming in early to mid-May and provides that first splash of reds/oranges for the season. This tough little perennial loves to self seed, and I let it pop up anywhere it wants in my yard – from full sun to full shade, in bone dry soil to consistently moist soil. Around the same time, my Capnoides sempervirens (pale corydalis or rock harlequin) starts to flower. This delicate little flower is an annual (sometimes biennial) that blooms right through till late fall. It, too, is a prolific self seeder, and though it doesn’t tolerate as much shade as wild columbine, it doesn’t seem too fussy about moisture. Often found in shallow soils on alvars, this plant is another with a two-tone blossom – pink and yellow.

Coreopsis lanceolata (lanceleaf coreopsis) starts to bloom in late May/early June in my garden and is another long-lasting splash of yellow – staying in continuous bloom well into mid-summer. And if you have the right soil (sandy, well drained), Lupinus perennis (wild blue lupine) flowers around the same time, and is host for the endangered Karner blue butterfly.

Phlox also starts to bloom in May – Phlox divaricata (wild blue phlox) and P. subulata (moss phlox) are Ontario natives, P. stolonifera (creeping phlox) is native just south of the Great Lakes. These range from blue, to white, to hot pink. (P. subulata is very common in garden centers – look for the true species rather than cultivars – which are denoted with a name in quotation marks, such as ‘Candystripe’ or ‘Ice Mountain’.) Be warned, though, that phlox seems to be a favourite on the menu for your local rabbits.

Phlox divaricata – wild blue or woodland phlox

There are lots more late-spring/early-summer natives, like Geranium maculatum (wild geranium), Tradescantia ohioensis (Ohio spiderwort), Oenothera pilosella (prairie sundrops), and even Packera paupercula (balsam groundsel), but this list will give you a good start.

July/August – this is when all the showier native plants come into their own. I personally like the yellows of Coreopsis lanceolata superimposed with the oranges of Asclepias tuberosa (butterfly milkweed) – a combination I discovered by accident when my milkweed self seeded into another garden bed. Our lilies (Lilium canadense and L. michiganense) give great shows in mid to late summer, as do many of our sunflowers, coneflowers, mountain mints, Monardas (didyma, fistulosa and punctata), and all of our Asclepias (milkweeds). Our Allium cernuum (nodding wild onion) looks lovely in part shade. See the table (below) for a list of several more late summer bloomers.

Asclepias tuberosa – butterfly milkweed – with monarch butterfly

September to snowfall – fall is the time for goldenrods and asters. (And, no, goldenrods do not give you hayfever – it’s the wind-borne pollen of ragweed that blooms at the same time that is the culprit.) Some goldenrods are very aggressive, and should only be planted in appropriately large spaces – like Solidago canadensis (Canada goldenrod), S. juncea (early goldenrod) and Euthamia graminifolia (grass-leaved goldenrod). But many are very well behaved, and even have interesting foliage and flowers. These include S. rigida (stiff goldenrod), S. speciosa (showy goldenrod) and the more unusual white goldenrods – S. ptarmicoides (upland white goldenrod) and S. bicolor (silverrod).

Solidago rigida – stiff goldenron (photo courtesy of Tina Gray)

As for asters – take your pick. There are so many, and they range from blues to pinks to whites, from short to tall, from full sun to part shade, from dry soils to wet. A few of my favourites are Symphiotrichum oolentangiense (sky blue aster) – a full sun, medium height plant that will be covered with gloriously blue blossoms; S. novae-angliae (New England aster) – a tall, pink to purple aster that handles being cut back in early summer by 1/3 to produce a shorter, thicker plant with a profusion of flowers; S. ericoides (white heath aster) – a smaller white aster with a lacy foliage and a profusion of tiny white blossoms in full sun; and the very tall (up to 6’ or more) Doellingeria umbellata (flat-topped white aster) which loves full sun and moister soil than many of the others.

Symphyotrichum oolentangiense – sky blue aster

Helianthus tuberosus (Jerusalem artichoke) flowers well into the fall – but be careful where you plant it as it will spread by its underground tubers. I planted mine in a plastic 45 gal barrel, cut in half and sunk into the ground. This way I get great tasting tubers in the fall and don’t have to worry about the plant taking over my yard. (This technique works well for other spreading plants, like common milkweed, the aggressive goldenrods, and others.) Helenium autumnale (sneezeweed) is another late bloomer, as is Coreopsis tripteris (tall tickseed) and Heliopsis helianthoides (false sunflower). And many of the earlier bloomers will still be blossoming well into the fall – plants like Monarda didyma (bee balm), Rudbeckia hirta (black eyed Susan), Rudbeckia laciniata (green headed coneflower), Silphium perfoliatum (cup plant), Silphium laciniatum (compass plant), and Vernonia missurica (Missouri ironweed).

Helianthus tuberosa – Jerusalem artichoke

Happy COLOURFUL gardening, all season long.

2_Colour in the less shady garden Download

Can I Have Continuous Bloom in My Native Garden? Part 1

Posted on May 9, 2022May 29, 2022 by ridgetownrick

Part 1 – The Shade Garden.

In northeastern North America (where I live), Mother Nature likes to constantly change things up. Few of our native plants stay flowering for more than a month or two, and some for only a few weeks. But, in nature, bees and other insects cannot survive for long periods without flowers, so there ARE plants blooming from early spring right through till snow covers them. Unfortunately, the bees (and we) need to search them out.

In the spring, our earliest blooming plants tend to grow in forests as spring ephemerals – they open before the trees leaf out, then disappear once the tree canopy closes in. Plants like Hepaticas (Hepatica americana and H. acutiloba), Jack in the Pulpit (Arisaema triphyllum), White and Red Trilliums (Trillium grandiflorum and T. erectum), Bloodroot (Sanguinaria canadensis) and Trout Lily (Erythronium americanum) all provide a nice, early splash of colour. By mid-May, though, most of these plants have finished blooming. If you have a shady yard, the rest of the season can be pretty bleak – one reason, I suppose, that non-native hostas are so popular. (Did you know that in Japan, where hostas are native, the young spring shoots are collected and eaten like asparagus?)

(Clicking on image will show larger image)

Hepatica americana – round lobed hepatica

In the fall, a few shade tolerant plants will blossom, taking advantage of the falling leaves that allow more light to reach the ground. These include Zig-zag Goldenrod (Solidago flexicaulis), Large Leaf Aster (Eurybia macrophylla), Upland White Goldenrod (Solidago ptarmicoides) and Blue Stemmed Goldenrod (Solidago caesia), which all do well in dry shade. If you have more moisture, you can add such things as White Snakeroot (Ageratina altissima), Sweet Joe Pyeweed (Eutrochium purpureum), Obedient Plant (Physostegia virginiana) or Blue Wood Aster (Symphiotrichum cordifolium) for a little more variety.

For shade gardens, ferns are a great choice to fill in the blank period between spring and fall. If you have some moisture, you can grow many different fern species, but if your shade is dry (the worst kind, from a gardening perspective), you are much more restricted. But there are some ferns that will grow in dry shade, though maybe not without a little help in very dry years. These include Lady Fern (Athyrium filix-femina), Christmas Fern (Polystichum acrostichoides), Eastern Wood Fern (Dryopteris marginalis) and Hay-scented Fern (Dennstaedtia punctilobula). Both the wood fern and the Christmas fern are evergreen, so they will provide that splash of green in the garden that we long for as the snow starts to melt. Hay scented fern can be quite aggressive, and is really only suitable if you have lots of space that needs filling, and don’t mind managing its spread once in a while. But even Ostrich Fern (Matteuccia struthiopteris) – the one we get edible fiddleheads from – does well in my dry full-shade garden under large Sugar Maples. In dry years they will go dormant in mid-summer if I don’t water them once in a while, but they always come back. They positively thrive in moist shade. Be forewarned, though, they will eventually spread beyond the garden setting – however, they’re easy to dig out to sell or give away to friends and family.

A variety of ferns in a cool, moist shady part of the garden

Most folks don’t realize it, but we do have some plants that can provide colour in the shade through the summer, if the shade isn’t too dense (think Tulip Tree, Kentucky Coffee Tree or a younger Sugar Maple or even a young Black Walnut – but not Norway Maple). Harebell (Campanula rotundifolia) will tolerate dry shade, starts to bloom in June and will go all the way through to the end of September. Evening primrose (Oenothera biennis) is another long-flowering plant that blooms from June to the end of August (sometimes even later) and tolerates light, dry shade. And then there are shorter blooming plants that that can stagger the colour throughout the summer.

During the first half of the summer, Canada Anemone (Anemonastrum canadense), Wild Geranium (Geranium maculatum), False Solomon’s Seal (Maianthemum racemosum) Hairy Beardtongue (Penstemon hirstutis) and even Virginia Spiderwort (Tradescantia virginiana) will do well in dry shade. (The more northerly Ohio Spiderwort (T. ohiensis) prefers a bit more light and moisture than its southern cousin, so if you have medium to moist light shade, it will do just fine). We also have several species of violets that will tolerate medium to dry soils in light shade – some will even tolerate fairly heavy shade. And violets come in a nice range of colours, too. Canada Violet (Viola canadensis) is white, Downy Yellow Violet (V. pubescens) is lemon yellow, and the very interesting looking Long-spurred violet (V. rostrata) is a pink or pale purple.

In my southwestern Ontario garden, Wood Poppy (Stylophorum diphyllum), which most books will tell you likes full sun to part shade and moist conditions, thrives under my large sugar maples in dry soil and starts flowering in early May. In a good year, it can still be flowering well into the summer, though normally it just lasts for three or four weeks. And contrary to everything I’ve ever know about Blue Lobelia (Lobelia siphilitica), I have volunteers coming up in that same dry shade year after year.

If you’re lucky enough to have moist shade, there are lots of options available for colour all season long. Most of the plants already listed will tolerate moister soils (with the exception, perhaps, of Blue Stemmed and Zig-zag Goldenrods). In mid-summer, if it’s not TOO dry, Black Cohosh (Actaea racemosa) will send up its tall white spires in shady settings in June and July, along with Poke Milkweed (Asclepias exaltata). And if the shade is not too heavy, even Wild Columbine (Aquilegia canadensis) will flower from May to July and Anise Hyssop (Agastache foeniculum) from end of June to the middle of September. Virginia Bluebells (Mertensia virginica) are an early bloomer that makes a great companion plant with Ostrich Ferns, sending up their pink and blue flowers just as the fens are starting to unfold. And the brilliant red of Cardinal Flower (Lobelia cardinalis) will light up the light-shade garden in average to moist soils in July and August.

So with a little careful planning, you can have continuous colour in most shade gardens. The list of suggestions provided here is by no means exhaustive – there are lots more plants that will grow in shade, but this will give you a start in your planning.

Next time: Continuous colour in the rest of the yard.