| 词条 | Verbena urticifolia |
| 释义 |
|name = White vervain |image = Verbena urticifolia 001.JPG |image_caption = Inflorescence |genus = Verbena |species = urticifolia |authority = L. }} Verbena urticifolia, known as nettle-leaved vervain[1] or white vervain, is a herbaceous plant in the vervain family (Verbenaceae). It belongs to the "true" vervains of genus Verbena. DescriptionWhite vervain has opposite, simple leaves on thin, rigid, green stems. The leaves look similar to those of Urtica, which is the reason for the plant being named urticifolia. The small flowers are borne in spikes; they open in summer and unusually for this normally bluish-flowered genus are white. The fruit is a dark- colored capsule with many brown and thin seeds. The entire plant except for the flowers and fruit is covered in stiff bristles. Relation to other vervainsIt might be closest to a group that might include such North American species as V. lasiostachys or V. menthifolia, and the common vervain (V. officinalis) from Europe. As these, it is diploid with 14 chromosomes altogether. The relationship of the swamp verbena (V. hastata) to these species is more enigmatic; its evolution might have involved hybridization with the White Vervain or a related species in the past.[2] Footnotes1. ^{{cite web |title=BSBI List 2007 |publisher=Botanical Society of Britain and Ireland |url=http://www.bsbi.org.uk/BSBIList2007.xls |format=xls |archive-url=https://www.webcitation.org/6VqJ46atN?url=http://www.bsbi.org.uk/BSBIList2007.xls |archive-date=2015-01-25 |accessdate=2014-10-17 |dead-url=yes |df= }} 2. ^Yuan & Olmstead (2008) References{{commons category}}
3 : Verbena|Flora of North America|Plants described in 1753 |
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