Weeds of Wednesday: Purple Bushbean & Phasey bean

Jane Schnee (Class of 2010)  identified purple bushbean (Macroptilium atropurpureum) growing up a cabbage palm at the Ansin Tract Conservation Area, before she led a walk for us there on 4/6/2019.  This perennial vine with a swollen taproot can grow to be 9′ long and is native to Texas, Mexico, and parts of central American and south America.

It was brought to Florida as a forage plant for cows.  If you are a cow, this plant is not a weed but a fabulous food source.    But, this plant is a weed in non-grazed areas in the U.S. and even in Australia.

Yes, its flowers are stunning in color — a dark, dark purple — shown below in a photo taken by George Bollis.

Its pods twist open to expel seeds a considerable distance.

Purple bushbean has trifoliate leaves with a densely hairy underside.  Its leaflets are slightly lobed.

The genus, Macroptilium, is derived from the Greek words macro (large) and ptilon (feather).  The species name, atropurpureum, means very purple.

A related species, phasey bean (Macroptilium lathyroides) grows at the Oslo Riverfront Conservation Area (ORCA), and the derivation of the genus name is more evident in its trifoliate foliage …

Its flowers have a similar shape but are much pinker and lighter in color.

Both of these members of the pea family, Fabaceae, are weedy in habit and should be removed from natural areas.