Vascular Plants of North Carolina
Account for Honeyvine - Cynanchum laeve   (Michaux) Persoon
Members of Apocynaceae:
Only member of Cynanchum in NC.
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Section 6 » Order Gentianales » Family Apocynaceae
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Author(Michaux) Persoon
DistributionOccurs only along or close to the Roanoke River floodplain, from Warren County downriver to the Williamston area of Bertie and Martin counties. A specimen from Catawba County is considered of uncertain provenance, owing more to unlikely habitat rather than to range. Note that the species has a broad range north and south of NC and there is little reason why it should only be found natively along this river.

This species occurs mostly to the west of NC, though it ranges widely across most of VA. It ranges from southern PA south to the FL Panhandle, with scattered records in SC. Why the range "stops" in the Piedmont at the VA/NC line is very odd, but it is certainly not owing to a lack of field work in northern Piedmont counties in NC.
AbundanceInfrequent to locally fairly common along the Roanoke River, upriver from Williamston. Essentially absent elsewhere, though it would be expected to be found in a natural setting elsewhere in the state in upcoming years, especially in the northern Piedmont. The NCNHP considers it as a Watch List species, a correct assessment according to the website editors, though the website suggests a W1 status (well known but scarce) as opposed to W7 (poorly known); this website also proposes a State Rank of S1S2, as it is not overly rare (S1) along this river.
HabitatThis is a wetland species, found mostly along the margins of bottomland and natural levee forests, but it also occurs in various other openings along the river, such as in damp thickets very close to the river. Most known sites are, indeed, within view of this brownwater river.
PhenologyBlooms in July and August, and fruits in September and October.
IdentificationThis is a quite long and slender herbaceous vine, sprawling and climbing over other vegetation to a height of over 6 feet high/long. It has opposite leaves that are ovate-triangular, with distinct basal lobes, but it is the shape of the base that is critical for identification. In this species the leaf base is not cordate (V-shaped), but is widely rounded, like a thumbprint. The leaves are dark green and a bit leathery, looking almost like an evergreen species; leaves are about 4 inches long and about 2 inches wide near the base, tapering to a narrow and pointed apex. A number of other vine species have ovate-triangular leaves, but perhaps only this one has a broadly rounded, thumb-like base. If in doubt, break off a leaf at its base, and look for the white milky sap. Various other species -- such as morning-glories (Ipomoea spp.) and Climbing Hempweed (Mikania scandens) -- lack the milky sap, whereas Matelea species (which do have milky sap) have leaf bases that are cordate. Helping to identify this potentially confusing species are the flowers and pods. This species has small clusters of pale yellow to creamy-white flowers in leaf axils, each cluster is about 1-inch across. Later in the season, the large pods appear; these capsules are long and narrow, but are smooth on the surface, and are about 6 inches long and 1-inch wide. In searching for this scarce species in the state, you will have to be very vigilant; there are quite a few climbing vines with ovate-triangular leaves that have pointed tips. Many of these will not have flowers or fruit, and thus you must check 1) to see if it has milky sap, and then 2) to see if the leaf base is rounded between the two lobes and is not V-shaped.
Taxonomic CommentsThough RAB (1968) has it named as Cynanchum laeve, as does Weakley (2018), it has gone by Ampelamus albidus in some references.

Other Common Name(s)Sandvine, Bluevine, Honeyvine Milkweed, Bluevine Milkweed, Smooth Swallowwort
State RankS1? [S1S2]
Global RankG5
State StatusW7 [W1]
US Status
USACE-agcpFAC link
USACE-empFAC link
County Map - click on a county to view source of record.
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Harry LeGrandMartin County, Roanoke River floodplain just N of Williamston MartinPhoto_natural
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