Vascular Plants of North Carolina
Account for Intermediate Dogbane - Apocynum floribundum   Greene
Members of Apocynaceae:
Members of Apocynum with account distribution info or public map:
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Section 6 » Family Apocynaceae
DistributionScattered over parts of the Mountains, and rarely along the VA border in the Piedmont (Caswell County). This species, which is probably a hybrid or hybrid-derived species from a cross between A. cannabinum and A. androsaemifolium, is still quite poorly known, despite being listed as a species in RAB (1968). Thus, the editors feel that the range map below is likely not representative of its range or abundance in the state, though it does appear to be mainly a montane species in the state.

This species has a huge range across Canada, south to GA and TX, perhaps not surprisingly overlapping that of the two presumed parent species.
AbundanceRare to uncommon in the Mountains, and very rare in the northern Piedmont. However, Wofford (1989) calls it "Common" in the Blue Ridge Mountains, though this includes parts of GA, TN, and VA, as well as NC. Thus, there is quite a dichotomy between Wofford's abundance status and the few specimen records from NC. As a result, the website editors feel that this entity definitely should be on the state's Watch List, as W7 (poorly known, more data needed to make an assessment of rarity). The editors also feel that S2? might be a better State Rank than S1?.
HabitatThis "species" occurs in similar habitats as the other two Apocynum species in the state, as would be expected. It grows in old fields, thickets, wooded and shrub borders, and roadbanks/roadsides.
PhenologyBlooms in June and July, and fruits in September and October.
IdentificationThis species is indeed intermediate in overall appearance between A. cannabinum and A. androsaemifolium. It is a fairly tall herbaceous plant, with a moderate branching, reaching around 4 feet tall, with fairly large opposite and elliptical leaves, to about 4 inches long and 1.5 inches wide. The flowers are in terminal clusters, often 10 or more in a cluster, and usually white to light pinkish-white, with pink veins, and about 1/5-inch long. They are bell-shaped with spreading petal tips. Compared with the latter species, A. floribundum has spreading leaves, whereas leaves of that species are drooping, and the flowers of A. floribundum are slightly smaller, with the corolla only twice as long as the calyx, as opposed to about 3 times as long as the calyx lobes in A. androsaemifolium. A. cannabinum has smaller, more tubular pale greenish-white flowers, which seldom extend much beyond the leaves. In general, this species tends to look quite a bit more like A. androsaemifolium than to A. cannabinum. As the latter species is so common in the state, observers who spot a dogbane that is clearly not this one should take care in the identification and may want or need to take a branch (with flower) to key out or collect.
Taxonomic CommentsSee Distribution. A number of references -- such as the Digital Atlas of Virginia Flora -- don't or won't even consider this "species" for inclusion, even though it occurs in the state or region. More references than not do not accept this as a full species, though Weakley (2018) does. In 2022, Weakley moved the name from A. medium to A. floribundum.

Other Common Name(s)None
State RankS1? [S2?]
Global RankGNA [G5?]
State Status[W7]
US Status
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