| Strophostyles helvola | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Rosids |
| Order: | Fabales |
| Family: | Fabaceae |
| Subfamily: | Faboideae |
| Genus: | Strophostyles |
| Species: | S. helvola |
| Binomial name | |
| Strophostyles helvola (L.) Elliott | |
| Synonyms | |
| |
Strophostyles helvola, commonly calledamberique-bean,[2]annual sand bean,[3] ortrailing fuzzybean[4] is a species of flowering plant in thelegume family. It is native to eastern Canada and the eastern United States.[1]
It is an annual to perennial herbaceous vine, up to 3 m (9.8 ft) long, with light pubescence on the stem, leaves, and pods. The trifoliate leaves are often divided into three lobes, in a fiddle-shape (panduriform). They possess unique pea-like pink-purple flowers (fading to cream-yellow), with a gradually curving keel petal (the keel petal is one of the most distinguishing characters among the species of the genus). The fruit ofS. helvola is up to 10 cm (3.9 in) long, containing shiny black seeds with hairy coats originating from the inner surface of the pods.[4][5] This seed coating lends the seeds buoyancy in water, which is thought to have contributed to its dispersal along major aquatic routes.[5]
Strophostyles helvola is primarily diagnosed by its keel petal (prominent, thin, curving away from the banner at the distal end); long, cylindrical pods; and highly lobed leaves (though not always lobed, andStrophostyles umbellata may also show lobing).[5]
When the seed pods are mature, they burst open to release the seeds.
In addition to thetype, at least one infraspecific taxon has been recognized,S. helvola var.missouriensis (S. Watson) Britton, although there is little evidence for distinct varieties of this species.[5]
A widely usedorthographic variant isStrophostyles helvula, although only the former is taxonomically accepted.[6][7]
Strophostyles helvola is a wild relative of the cultivated common bean (Phaseolus vulgaris), and could serve as an important model for understanding how herbaceous legumes adapt to different stressful environments. Specifically,S. helvola has coastal populations which show high salinity tolerance due to up-regulated genes.[8]
It is native to eastern Canada and the eastern United States.[1] This bean grows in many habitat types, including disturbed areas, where it is apioneer species, taking hold in areas where few other plants grow, and in several types of soil, especially sandy types, and it can grow in dry or moist conditions.[4] It can often be found in seasidedune habitat, wherearbuscular mycorrhizae help it withstand saline conditions.[9]
This plant was used medicinally and as food byNative American peoples. TheHouma people used it to treattyphoid and theIroquois used it topically forpoison ivy irritation andwarts. TheChoctaw people used the boiled, mashed roots for food.[10][11] Discovery of large quantities ofS. helvola seeds in archaeological sites also suggests a use similar tocommon bean at one time; though the seeds are smaller than cultivated bean, it is nutritionally similar and possesses the largest seeds and pods for the genus.[12] The pods have been used in the present day as a sauteed vegetable in South CentralMindanao,Philippines.[13]
