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 Well-Known Plant: Yarrow - Achillea millefolium - Herbe à dinde

The star of the day is one of the most broadly-distributed and -recognized wildflowers around: Achillea millefolium (common yarrow, also many other names).

Achillea millefolium inflorescence

This species (actually a huge complex of subspecies) is native more or less to the northern hemisphere's temperate zones, but particular subspecies are native to more restricted areas. This helps to understand the US range map of this plant, which lists the species as both native and introduced on most of the North American continent. This is because some subspecies are native, and others are introduced (particularly from Europe). The Canadian range map is considerably less detailed, going for the simple statement that the plant is native to all parts of Canada. This plant is listed as weedy/invasive in the US [1] but does not have weed status in any of the provinces or territories where such statuses are conferred [2].

Achillea millefolium whole plant

One of the main reasons for Achillea millefolium's fame is its array of purported and variously justified medicinal uses. This plant is a very popular herbal remedy [3,4] with a very long history of use in traditional medicine [3,4,5,6,7,8] for a wide variety of ailments. Modern analyses and tests have confirmed its efficacy as an anti-inflammatory at least in vitro [9], and there is some speculation (which I mention in my previous post about this plant) that the salicylic acid in the plant may make it an effective painkiller [3]. Other claims about the plant's medicinal value are currently insufficiently assessed to make a judgement on.

Achillea millefolium inflorescence lateral view

Regardless of its particular efficacy as a medicine, I do enjoy a cup of tea with the flowers or leaves of Achillea millefolium from time to time. The flavour, though strong, is pleasantly herbal. There is evidence that prolonged use can be potentially harmful and that it is possible to suffer allergic reactions to the plant [3,4], so I do not recommend that anybody consume it too frequently.

Achillea millefolium being pollinated by flies

Achillea millefolium is a hardy, drought-resistant [3,4,5,6,8,10] perennial with an extensive root system [3,4,5,6,8] that makes it suitable for habitat restoration in areas where erosion control is needed [6]. It is an obligate outcrosser [3,6], meaning that it must be pollinated with pollen from a different individual in order to produce seed. It is pollinated by insects [3,8], including beetles, flies, syrphid flies, wasps, and bees [6].

Heal-All - Prunella vulgaris - Herbe du charpentier

I am back home visiting with my parents right now, in the Upper Gatineau. My mother and grandmother asked me to identify a plant which is growing quite abundantly down by the dock, and I am glad that they did, because it was Prunella vulgaris (heal-all, self-heal), a member of the Lamiaceae (mint family).

Prunella vulgaris - whole plant

Prunella vulgaris is native to most of North America [1], though the USDA indicates that it is introduced to parts of Canada (provinces & territories where it is also native) [1]; the Plants of Canada database seems to disagree with this judgement, not indicating anywhere that Prunella vulgaris is considered introduced in parts of Canada [2]. A more detailed reading of the maps indicates that actually the USDA is claiming that Prunella vulgaris var. vulgaris is introduced in most of Canada, but that Prunella vulgaris var. lanceolata is native [1]. So, to see if I could resolve this disagreement I searched the subspecies on the Plants of Canada database but found that though the subspecies are recognized, there is no data and they are referred back to the parent species page [3,4]. For the moment, therefore, no resolution can be made. I will assume that there is some but perhaps insufficient evidence for the claim that Prunella vulgaris var vulgaris is present and introduced in Canada.

Prunella vulgaris inflorescence

If we're speaking purely of the parent species, we see that it is indicated as weedy [1], and has no other special status in the US [1]. It does have special status in parts of Canada, however: it may be at risk in the Yukon and Saskatchewan, and is unassessed in Newfoundland & Labrador [2].

Prunella vulgaris inflorescence

How are we to reconcile such a messy picture? Invasive or potentially invasive in the US, potentially at risk in Canada? Well, it is likely that all of these claims are true. Plants with very broad distributions will tend to have a varied story because of the wide variety of circumstances and conditions that they grow under. It is likely that the plant is weedy and spreads easily; it is also likely that external factors are overcoming that characteristic in the Yukon and in Saskatchewan.

Prunella vulgaris inflorescence

Prunella vulgaris has a long history of use in folk medicine [5,6,7]. There is at present limited evidence for most claims about its medicinal value (I can't find more than one or two in vitro studies to justify any of the claims). That said, the plant is edible and non-toxic so if you feel like giving it a shot there doesn't seem to be any harm in trying (whether or not it is effective is a different question). Given that it's edible, I have given it a taste. It is relatively plain-tasting but contains some undertones common to plants in the Lamiaceae (mint family); I wouldn't go out of my way to eat it as a green, given its relative blandness, but it adds a nice accent to a cup of tea.

Prunella vulgaris developing infructescence

Prunella vulgaris is a source of nectar for bees and butterflies (there was a large bumblebee visiting when I went to identify the plant) [7], and it serves as a larval host for Colias philodice (the clouded sulphur butterfly) [7], which is a common little North American butterfly.