Vascular Plants of North Carolina
Account for Smooth Milkpea - Galactia volubilis   (L.) Britton
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Section 6 » Order Fabales » Family Fabaceae
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Author(L.) Britton
DistributionThis is the formerly named G. regularis in most references, including most recent ones, and that species is conversely named as G. volubilis, to confuse just about everyone! The "new" G. volubilis ("old" regularis) apparently occurs throughout the Coastal Plain, possibly into the far eastern edge of the Piedmont. However, to further confuse matters, two "new" species -- Galactia brachypoda and G. minor -- have been split from G. volubilis. It is not clear yet how many of the counties shown on the map below are still actually the new/post-split G. volubilis. However, as Weakley's (2018) map shows the "new" G. volubilis as "common", many or most of the counties shown on the range map below may still be this revised species.

This is a mostly Coastal Plain species, ranging north to southeastern VA, and south to southern FL and west to eastern TX.
AbundanceCommon in the Sandhills region, and probably also frequent to common in most other parts of the Coastal Plain, with collections from nearly all counties. Scarce in the far northeastern counties.
HabitatThis is a species of sandy places, such as pine/scrub oak sandhills, dry or sandy edges of woodland borders, and other sandy clearings. Differences in habitat among this species, G. brachypoda, and G. minor are not apparent or clear at the present time, though the last is the most restricted one in the state (geographically).
PhenologyBlooms fairly early for a Galactia, from May to August, and fruits from July to October.
IdentificationThis is a trailing or weakly climbing vine that can reach 4-5 feet long. The stem has some hairs, and these may be backward slanting (retrorse) hairs, but it is not as villous/hairy as stems of G. regularis, which is also numerous in the Coastal Plain. The 3 leaflets of G. volubilis are somewhat differently shaped from those of G. regularis; they are ovate to lanceolate and about 1 inch long and notably narrower, but the widest part of the leaflet is just below the midpoint, toward the base. The leaflets average about 2/5-inch wide, as opposed to 3/5-inch wide on the more rounded leaflets of G. regularis. The leaflets of G. volubilis are somewhat thin in texture, as opposed to somewhat thick in the other. Also, Nesom (2015) notes that the undersides of the leaflets of this species are mostly glaucous (whitish). Lastly, G. volubilis has relatively large flowers; the rose to pink flowers are nearly 1/2-inch across (9-14 mm), as opposed to just 1/3-inch (7-10 mm) in G. regularis. Sorrie (2011) notes that in this species the standard (the large, top petal) is spread back such that the open flower is about "flat" (180 degrees); the flowers of G. regularis have the standard spread only about 90 degrees from the lower petals. Observers in the Coastal Plain will run into milkpeas often in their walks in drier habitats. Be careful of the identifications, as all six species do occur there, but it appears that this species is perhaps the most common of the group (along with G. regularis).
Taxonomic CommentsThe former G. macreei was considered as a part of this larger species by many references. As mentioned above, most references considered, and many still do, this species as G. regularis (such as in RAB 1968).

Other Common Name(s)Confusing. Nearly all references use, or better said, still use Downy Milkpea for the common name. However, this may have been for the taxon now named as G. regularis, which has downy stems. However, the editors feel that this common name is now "misapplied", to provide a word used for scientific taxa named incorrectly. Sorrie (2011) uses the names of Smooth Milkpea and Common Milkpea for this taxon. As the stem is relatively smooth, certainly as compared with G. regularis, this website uses Smooth Milkpea as the preferred (but not most prevalent) common name, in order to avoid confusion!
State RankS4 [S5?]
Global RankG5
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