The Hairy Problem of Defining Species, with Hoary Vervain -- Verbena stricta -- Verveine veloutée

Yesterday, I posted about Verbena hastata, which is native to this region (Montreal area). Today, I post about Verbena stricta, which is native in Ontario but actually introduced here in Quebec. US range map here, Canada range map here. Now, it is possible that Verbena stricta is native to parts of Quebec and introduced to others. Unfortunately, I can't find any resources about it so I only know that it is listed as introduced in Quebec [1]. It is native to much of North America [2], and is considered as weedy/invasive in parts of the US. As with Verbena hastata, this designation within the native range of a species indicates that it is a strong competitor (eg an aggressive spreader) and under some circumstances can end up squeezing out other native plants. And, as demonstrated by its presence in Quebec where it was not originally native, the weedy classification does indicate a capacity for invading new habitats as well.

Verbena stricta inflorescences

Though this and yesterday's plant are both vervains, they are not the same. Verbena stricta has considerably larger flowers and inflorescences, and has a lot of trichomes [3,4,5] (fine hairs on the surface of the plant).

Verbena stricta full plant

Trichomes are an interesting anatomical feature of many plants. They can serve many different functions: they can deter herbivory (trichomes of this variety will often be sharp and stiff, or will deliver a painful irritant to the unwary brusher-by); they can protect against frost; they can reflect excessive sunlight; they can reduce evaboration; and they can even enhance fog drip in order to improve water collection.

Verbena stricta inflorescence

One issue which complicates matters a bit when trying to distinguish species of Verbena is that many members of this genus can readily hybridize [3,6].

This statement may immediately twig some concern in the minds in those who have taken an intro to biology course. After all, aren't species largely defined by reproductive isolation (the inability to produce offspring by crossing two populations)? Well, sort of. Defining species is a complex issue.

To an extent, the definition of species (by which I mean the point of genetic relatedness beyond which we identify groups of organisms as "same"), is a matter of pragmatism and judgement. This doesn't mean that we lack any standards for determining whether populations are members of a single species, but it does mean that exactly what judgement we make will be influenced by context. Depending on the purpose, we might make it a bit more stringent in some way, eg produce viable offspring and be morphologically/genetically similar to a given degree (a common standard with plants).

So where some might see a single species [eg], others might see a species complex [eg] (a group of closely interrelated species which are so similar as to sometimes make it difficult to distinguish between them). Depending on the purposes and interests of the individuals involved, both of these interpretations can be valid.

Verbena stricta inflorescence

So am I actually saying that depending on the context, Verbena stricta could be either a single species or a species complex (or even part of the broader group "Verbena")? Yes, I am. This kind of fuzzy imperfection of definition stems from our practical need to categorize the inter-relatedness of life, which is functionally much more continuous than categorical. People don't like it because it's messy, but that messiness is a product of the attempt to categorize a continuum. The lines we draw will always be in some sense arbitrary. That doesn't mean there's no value in categorizing, as long as we're clear about what we're doing and how we're making the call.

In many aspects of biology, we use the standard of intercompatibility (the ability to produce viable offspring) to define the species because reproduction is central to relatedness (genetic/functional relatedness is a pillar of many avenues of scientific inquiry), so it is a place to draw the line which has a lot of practical applications. But there are also other places to draw the line that are useful or informative in a variety of applications.

Native Plants for the Pollinator-Conscious Gardener, Part 1: Blue vervain - Verbena hastata - Verveine hastée

The vervains (Verbena spp.) have started blooming in the wooded part of the Notre-Dame-des-Neiges cemetery. They are quite beautiful and where I was, they were absolutely teeming with a wide assortment of pollinators including bees, syrphid flies, skippers, and butterflies. Most of the shots I took actually were photobombed by a variety of pollinators!

Today, I would like to talk about Verbena hastata (blue vervain, fr verveine hastée). This beautiful flower is native to North America (US range map here, Canada range map here). It is listed as potentially weedy/invasive in the US [1], which, within its native range, means that it is a strong competitor and may squeeze out other plants under some conditions. This plant is secure in most of its native range [1,2], with the exception of British Columbia and Saskatchewan, where it may be at risk [2].

Verbena hastata inflorescence

This gorgeous flower can get pretty tall, anywhere from 2 to 5 feet [3,4,5,6]. It prefers moist soils [3,4,5,6] but there were lots of them growing at the top of the mountain, on the slope, and that is hardly a moist location so I would say it can prosper elsewhere. Verbena hastata has a solid upright form, as seen here:

Verbena hastata - full plant view

Verbena hastata is a member of the genus Verbena (vervains), a family with a long history of medicinal use. Verbena officinalis, the common vervain, is a popular garden plant possibly for its particular history in Europe as a medicinal plant [7], but Verbena officinalis is not native to North America [8]. The vervains are used medicinally to treat a number of ailments. Verbena hastata specifically, has been used to treat depression, fever, coughs, cramps, headaches, and jaundice [3,6,7]. There is, however, currently insufficient scientific evidence to back up the use of vervains to treat most of the ailments associated with them [9]. Please note that Verbena hastata is known to interfere with blood pressure medication and hormone therapy, and that in large doses can cause vomiting and diarrhea [3,6]. Do not consume this plant in any form if you are taking medications it could interfere with, and do not consume it in large doses.

Verbena hastata inflorescence

Verbena hastata is very attractive to a wide range of pollinators, including long-tongued bees, short-tongued bees, cuckoo bees, miner bees, halictid bees, and the verbena bee (specialized to Verbena spp.), as well as wasps, syrphid flies, true flies, beetles, butterflies, skippers, and moths [3,4,5,6]. At this point you may have noticed that I have listed essentially the entire range of insect pollinators. The plant also serves as a larval host for the common buckeye butterfly and feeds the caterpillars of verbena moth [3,5,6]. As a bonus, Verbena hastata is also attractive to some birds, for its seeds: cardinal, swamp sparrow, field sparrow, song sparrow, and the slate-coloured junco [3,5].

So if you are considering planting vervain in your garden, please consider taking this lovely native alternative to the more commonly selected Verbena officinalis. After all, the native Verbena hastata is beautiful, makes a decent tea (with the caveat about dose size and medical contraindications firmly in mind), and is great for the pollinators!

A Few Fun Finds Outside of My Area of Expertise

So I decided to make a quick post today just showing a few of the unusual things I've seen on my wanderings that I don't have much to say about.

First up, we have Hylatomus pileatus (pileated woodpecker), a normally shy bird which appeared to consider it a worthwhile trade to be closer to humans than regular comfort in order to get at the bugs in this dead log.

Hylatomus pileatus -- photographed in the Mont-Royal Park

This also happens to be the only time I've ever seen Hylatomus pileatus eating on the ground. This probably has more to do with the fact that most of its food is in standing tree trunks, rather than a particular habit or preference.

We also have Anaxyrus americanus, an american toad, which is very common in the area. I see toads all the time at the lake but rarely ones of this size (presumably the ones that manage to get this big, get this big because they're good at going unnoticed). I love the gold eyes of this species.

Anaxyrus americanus, photographed in the Upper Gatineau region

Finally, I would like to make an addendum to my post about Celithemis elisa (the calico pennant). At the time of posting, I had only gotten a picture of the male. I can now add a picture of the yellowy-beige female.

Celithemis elisa - male (image previously posted here)

And here is the female. She sports all the same markings, but in a different colour palette:

Celithemis elisa - female

How Does a Plant Qualify for Noxious Weed Classification? Hoary Alyssum, Berteroa incana

Our star of the day is Berteroa incana (hoary alyssum, berteroa blanche), an introduced invasive species here in North America which is originally native to Eurasia [1]; it is a member of the Brassicaceae (mustard family). US range map here, Canada range map here. This plant is marked as weedy/invasive in the US [2], but is not listed federally as a weed in Canada [3]. Berteroa incana has noxious weed status in Michigan [2], and in Alberta, British Columbia, and Saskatchewan [3].

Berteroa incana inflorescence

I've mentioned a couple of other plants with noxious weed status on this blog: Leucanthemum vulgare, and Alliaria petiolata. So at this point you may be wondering what a plant has to do/be in order to obtain the noxious weed classification.

The answer to this question isn't always entirely straightforward, because there are a number of potential reasons for governments to confer noxious weed status on a plant, and because sometimes plants which exhibit similar traits to legally recognized noxious weeds aren't on the list for a variety of reasons (eg lack of resources, petition for review hasn't been tabled before the assessing body, insufficient scientific data, management concerns, political reasons, economic reasons).

Berteroa incana whole-plant view (in among a rambling pile of other plants)

The nice thing about Berteroa incana for the purposes of this discussion is that it exhibits more than one of the common traits that will lead a plant to be classified as a noxious weed. For example, it used to hold the noxious weed classification in Michigan [4], because it had been implicated in loss of pollinator diversity and therefore constituted a presence disruptive and deleterious to native ecosystem function [5]. It is unclear from my research whether this hypothesis has been disproved or if the plant has since been removed from Minnesota's noxious weed list for other reasons.

This plant's noxious weed status in Michigan must be attributable to agricultural or environmental undesirability, as these are the criteria listed by the state for plants to qualify for the noxious weed list [6]. It is possible that Berteroa incana was assessed as both; the list provides no further detail.

Berteroa incana inflorescence

Berteroa incana's noxious weed status in Alberta and British Columbia is explicitly outlined as being due to its toxicity to horses [7,8], and in British Columbia also because it interferes with alfalfa crop quality [8], by invading alfalfa fields and competing with the forage plant; it also ends up in the hay and is considerably less nutrient-rich than alfalfa, thereby reducing the nutritious value of the fodder produced.

Phyciodes cocyta collecting nectar from Berteroa incana (photo posted before on this post)

So a plant can end up on a noxious weed registry because it is particularly deleterious to ecosystem function, or because it is undesirable from an agricultural or environmental standpoint. If I have a reliable source on the matter, I will generally indicate why a particular plant is listed as a noxious weed. But if I don't, it is one of these reasons (and I couldn't find out which).

As for what to do about this plant... well, small populations can simply be pulled by hand [8], or in some places and contexts it may be appropriate to treat with an herbicide (2,4-D, dicamba, or glyphosate) [4,8].

I am remembering a visit I made to Toronto a few years back in August where I lost my voice because of the smog. The same thing is happening now with all this heat and traffic in Montreal, only it's not a visit; I'm stuck here until the end of the month and I'm losing my voice fast (I'm already at the stage where I can no longer hum). I had forgotten how hard it can be to breathe in a large city in summer...

You Don't Have to See It to Notice It: Wood Nymph, Moneses uniflora, Pyrole à une fleur

In my meanderings at the lake (my parents's property in the Upper Gatineau), I came across some Moneses uniflora (aka wood nymph, oneflower wintergreen, single delight, & many other names) that was well-placed for some photos.

Moneses uniflora

For those familiar with the property, it grows fairly abundantly in the cedar bush. Today's shots were taken by the metre-deep pond.

For those unfamiliar with the property, this plant is native to and found in temperate, moist coniferous forests in the Northern hemisphere [1] and was thus quite predictably found in an area where the water table is quite high (we know of at least one spring letting out in the area; the place is crisscrossed with little streams and puddles and is always very damp; it is not a place you walk if you plan to keep your feet dry), and which is populated primarily by Thuja occidentalis (white cedar). This is its native and natural habitat.

The pictures were taken quite close up (I had to lie down on the ground to take it and rose predictably quite damp as a result), so the size of the plant is not immediately obvious. In spite of its reasonable stature in the photos, Moneses uniflora is actually a very small, unpreposessing flower; the one I photographed here appeared to be quite typical of the population and was no more than 3 or 4cm high, though some sources seem to indicate that it can grow as big as 6 inches tall [2] (this may be more likely in warmer climates with longer growing seasons).

Moneses uniflora side view ; note the prominent pistil

It is very likely that people have walked by this plant many times without ever noticing it, small and plain as it is. But though people may walk by without taking note of it, it is possible that they still perceive its presence. It isn't visually dramatic, but it produces a strong and very pleasant fragrance [2] that, where it grows abundantly, sweetens the air. The scent of this flower is part of the sweet, moist, earthy smell I associate with the cedar bush.

The strong fragrance of the flower is attractive to bees, but the plant is in this respect deceptive; they will find no nectar in these flowers [2]. Nevertheless, the bees are able to collect pollen, which rather than being borne on the surface of the anther, is actually inside it. There is a pore at the tip of the anther through which pollen will fall when a bee shakes the anthers by vibrating its wings [2], thereby shaking the pollen loose -- this is called buzz pollination (which is a fascinating topic for another post).

Moneses uniflora

From a North American perspective, Moneses uniflora is native to much of the continent (US range map here, Canada range map here). It is endangered in Connecticut and Ohio, and threatened in Rhode Island [3]. It is secure in most of its native Canadian range, except Nunavut where it may be at risk and Newfoundland & Labrador, where its status has not been assessed [4].

A few sources suggest the Moneses uniflora's potential medicinal use against colds [2,5] and as an antibacterial agent [2].

Because of my mother's musical predilections, I associate all this summer heat with the Tragically Hip, whose music my mother frequently played when we were driving up to the lake. Here's to the beauty of a Canadian summer. I hope you all are able to make the most of it.

Wasps: Not Just Flying Agents of Pain

One of the things I encounter a lot when I talk to people about pollination is an intense fear of bees, and most especially of wasps. But wasps don't just sting you (and most won't sting without provocation); they also are pollinators. While on holiday at the lake, I captured a great series of a wasp worker hanging out on Achillea millefolium.

Unknown species of wasp on Achillea millefolium

Wasps are generally less hairy/fuzzy than bees, so they don't carry pollen as efficiently. But less efficient pollination != no pollination. Indeed, wasps are important pollinators in many ecosystems.

Another possible reason that wasps aren't such efficient pollinators of bees is that they don't (for the most part) rely solely on flowers for food. This individual actually may have inadvertently provided pollination services to the flower, but wasn't there collecting either nectar or pollen. She was dining on something else entirely:

A wasp eating something - note the ball of wax-yellow stuff

So I wondered what in the world she was eating. I looked from the front angle, hoping another angle might illuminate the matter:

Wasp eating something -- ball of stuff still unidentifiable

Nope, that was no help. Still a generally formless lump of gunk.

A quick glance around the environs, however, provided the answer:

Seems like a colour match for that wasp's meal

This dead grasshopper was on the stem of the flower where I found the wasp, and judging by the colour match and the big old hole in the dead grasshopper's abdomen, I suspect that the wasp found herself a rich source of protein and was taking advantage.

I suppose one animal's rather grisly find is another's feast.

Anyway, wasps will seek out other sources of protein (often to feed their young), including other insects, whereas bees generally don't. This reduced reliance on flowers may make them less likely to do the systematic flower-by-flower collection that also makes bees such suitable pollinators for flowers.

Wasps are actually an excellent biological control agent, as many of them have preferred prey which are pest insects on crops. I encourage them in my own garden because they're so efficient at getting rid of unwanted insects.

These oft-maligned insects are actually pretty awesome -- as long as you don't swat them or approach their nests late in the season.

What Do These Images Have in Common?

There are quite a lot of deer at the lake. So many that it wasn't hard to get a few photos while I was visiting with my family. This is the best of the bunch:

Odocoileus virginianus - white-tailed deer

Of course, when I say "deer", I mean Odocoileus virginianus, the white-tailed deer. This species is extremely abundant in many places and this excessive abundance (in response to the elimination of its natural predators, eg cougars, wolves) has had large impacts on plant populations. Odocoileus virginianus browse extensively on plant matter, especially low branches, shrubs, and herbaceous plants. Their presence seems to assist invasive species spread, by weakening native species (which they prefer to eat compared to invasives) and thus reducing their competitiveness.

People who visit at the lake will frequently ask me about this:

Shoreline of the lake

What's up with the straight, level trimmed line of the branches on the shore? A number of amusing theories have been proposed, from snow-reflection microclimates to the lake association hiring professional landscapers to trim.

But there is a connection between the deer, and this straight line.

The lake's shore primarily composed of Thuja occidentalis (northern white cedar), which is one the local Odocoileus virginianus population's primary winter food sources. In the winter the lake freezes, and the deer go out on the ice and have a chomp. So this straight line actually shows the reach limit of the deer for browsing.

In ecology terms, this is called a browse line. Overbrowsing certainly seems to be an issue at the lake; the forest understory is in many places quite bare, and there are virtually no new cedar, maple, or oaks growing in recent years because when they reach intermediate height (tall enough to poke over the snow in winter, not tall enough to exceed the reach of deer), they are browsed to death and that's that. This is a documented problem in many places which have overpopulations of Odocoileus virginianus.

It was just gorgeous at the lake last week, so I will sign off with a picture:

Island on the lake