Monday, July 20, 2015

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!

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