Saturday, June 11, 2022

Piedmont Leatherroot/ Lupine Scurf Pea - Orbexilum lupinellus


Piedmont leatherroot (Orbexilum lupinellus) is a member of the legume family and one of three species native to Florida. These are easily overlooked in the understory when not in bloom, but their exquisite flowers cannot be ignored during their brief flowering period from May to early July.  It is a perennial herbaceous plant that dies back to its deep taproot in the winter and reemerges again in early spring. 

As its common name suggests, Piedmont leatherroot, occurs in the Piedmont region of the Southeastern US, though it is generally rare outside of Florida. There are scattered occurrences of this plant in Alabama and Georgia, north to North Carolina.  Throughout this range, it is confined to well-drained sandy soils of open woodlands and sandhills. In Florida, it occurs in much of north Florida, south to Hillsborough and Polk Counties.

The foliage of this species is unmistakable.  It forms a mass of very thin stems that can reach a mature height or length of 4 feet.  Often, mature plants fall over a bit and form more of a mass of stems than a completely upright plant.  The leaves are exceedingly thin and about 1-2 inches long. They are divided into 5-7 palmately dissected leaflets and this gives the plant a very busy aspect.

Flower stalks arise several inches above the ends of the stems. Individual flowers are typical of most legumes in terms of structure. They are a rich purple in color with a deeper purple throat, but only about 1/4 inch long.  A small "pea pod" fruit is formed following pollination. That is likely facilitated by small bees.

The genus Orbexilum contains some very attractive species, but none have been propagated commercially by members of FANN - the Florida Association of Native Nurseries; perhaps because the flowers are diminutive. The genus also is reported to be a poor fixer of nitrogen compared to most legumes.  Look for this species in the late spring if you are in a sandhill or in xeric open woodlands.  You may easily miss it at other times. 

These photos were taken by my friend, Alex de la Paz and are used by permission.  

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