Saturday, March 23, 2024

Florida Milkvetch - Astragalus obcordatus


Florida milkvetch (Astragalus obcordatus) is a perennial legume (bean/pea family) that is nearly endemic to Florida.  Isolated populations have been vouchered in Mississippi, Alabama,  and Georgia, but it is found throughout much of the Panhandle and the northern half of peninsular Florida. Throughout its range, it is most commonly found in open mesic to xeric uplands.

Although this is a widespread and common genus, Florida milkvetch is only one of two species found in Florida. The other species, bearded milkvetch (A. villosus) is an upright species with much smaller flowers that are yellow instead of pinkish purple.  As the above photos, taken by my friend, Steve Coleman and used by permission, demonstrate, Florida milkvetch is a prostrate species that creeps across the ground - often for several feet away from the center.  They sometimes root at the nodes and/or by underground rhizomes.  The stems are solid (nearly woody in appearance) and often glabrous - though they can sometimes be sparsely hairy.  The compound leaves are composed of many (10 or more) small rounded leaflets with a noticeable notch at the tip.  The leaflets are opposite each other along the petiole and hairy on one or both of the surfaces.  The leaves and stems spread outward across the surface of the ground.

Flowering occurs in the spring.  Clusters of these appear at the tips of the many stems.  They are typical in shape to most other members of the legume family with a noticeable keel and fused lower lip.  They are a rich pinkish purple with darker striations in the petals.  Although I have no observations of this, I suspect that it is mostly pollinated by large-bodied bees.

Legumes are important species for fixing nitrogen in the soil and Florida milkvetch produces these types of root nodules.  As a genus, Astragalus has been used as an herbaol medicine, commonly combined with other herbs to treat upper respiratory infections, hayfever, chronic fatigue syndrome, and kidney diseases.  The efficacy of this not scientifically documented, however, and I could find no literature regarding Florida milkvetch.  Although Astragalus roots and tinctures are available online, I could find few sources of this genus for sale as live plants and none for Florida milkvetch. This is a species to admire when found afield.

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