Vicia americana (American Vetch)
|Also known as:||Purple Vetch|
|Habitat:||part shade, sun; fields, prairies, open woods, thickets, along roads|
|Bloom season:||May - September|
|Plant height:||1 to 3 foot vine|
|Wetland Indicator Status:||GP: FACU MW: FACU NCNE: FACU|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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2 to 9 flowers in loose clusters (racemes) arising from leaf axils in the upper part of the stem. Individual flowers are a typical shape for a member of the pea family, slightly elongated, ½ to ¾ inch long. Flower color ranges from pink to purple to blue. The calyx holding the flower is hairless to minutely hairy, with 5 broadly triangular lobes, the lower lobes up to twice as long as the short upper lobes, and all rather shorter than the calyx tube. Flower stalks are minutely hairy.
Leaves and stem:
Leaves are compound in groups of 4 to 8 pairs, with a tendril at the end of the leaf that winds around other plants for support. At the base of the stalk is a pair of leafy appendages (stipules) that are up to 1/3 inch long, sharply pointed at both ends, with 3 sharp teeth in the lower half. Leaflets are narrowly egg-shaped to elliptic and may have rounded, blunt or pointed tips. Each is up to 1½ inch long and about ¼ inch wide, toothless and hairless, becoming smaller towards the end of the leaf. Stems are angled, but otherwise smooth.
There are several members of the pea family that are climbing vines with racemes of purplish or pinkish flowers. One major distinguishing feature is the stipule at the base of the leaf stalk, which is unique for many species; American Vetch is unique with the 3 sharp teeth on the lower half of the stipule. The non-native vining vetches tend to create dense, tangled masses where American Vetch is more spindly, with fewer flowers in looser clusters. When not in bloom, American Vetch plants with rounded leaflets might be mistaken for Crown Vetch (Coronilla varia), but Crown Vetch has no tendril at the end and its stems are leafier, plus Crown Vetch has round flower clusters. There are 3 recognized subspecies of Vicia americana, 2 of which are found in Minnesota: subsp. americana is widespread, subsp. minor is uncommon. The differences between the two subspecies are not well documented but minor may have narrow, thick leaflets, 4 or fewer flowers per cluster, and a limited habitat of short-grass prairie, with americana more tolerant of moister soils, have broader, thin leaflets, and 4 or more flowers per cluster.
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Photos by K. Chayka taken in Ramsey County. Other photos courtesy Peter M. Dziuk.
Have you seen this plant in Minnesota, or have any other comments about it?