| Author | Michaux | |
| Distribution | Weakley (2024) has now changed this species name to Convolvulus purshianus, from C. stans. This is a recent split of a part of the former Calystegia spithamaea, with the other portion of that former species now assigned to Convolvulus catesbeianus. In general, the more easterly records of C. spithamaea now refer to this species, but some from the Mountains do as well. This species as now defined occurs sparingly over the Piedmont and Mountains, east to Granville and Wake counties.
This is a mid-Atlantic species, ranging from central PA south only to central and western NC.
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| Abundance | Somewhat unsettled owing to the recent shuffling of taxa in this genus, but rare to locally uncommon, possibly somewhat more numerous. The NCNHP has a State Rank of S2S3, and lists it as a Watch List species. The website editors agree, but favor a W7 (rare but poorly known) status is more appropriate than W1 (rare but relatively secure). | |
| Habitat | This species requires high pH soil, but generally it grows on dry soils of glades and barrens, and other open, dry woods and sunny edges. Outside of NC, it often grows on shale barrens. | |
| Phenology | Blooms in May and June, and fruits soon after flowering. | |
| Identification | The members of the genus are herbaceous vines. This species is not twining and grows only up to 2 feet long; the very similar C. catesbeianus twines in the upper parts of the stem, which can grow to 3-4 inches long (0.8 - 1.4 m). All have fairly large and ovate leaves, usually cordate at the base, that are alternate on the stem. This species has "leaves overtopping the stem apex by 1.5-6 cm" (Weakley 2018), whereas C. catesbeianus has "leaves overtopping stem apex by < 1 cm" (Weakley 2018). The large white funnel-shaped flowers are 2-3 inches long and spread, as are others in the group. In this species, the flowers are only from the lower leaf axils. Some other species have flowers from the upper and middle leaf axils. The very similar C. sericatus has its leaves "densely white-tomentose beneath" (Weakley 2018), as opposed to "pubescent or glabrous, but not densely white-tomentose beneath". Needless to say, the recent splitting and shuffling of species in the former Calystegia have meant that identifying these species is now tricky, and you likely will need to refer to botanical keys such as in Weakley (2018). | |
| Taxonomic Comments | See Distribution. In general, this is part of the former Calystegia spithamaea complex. Note that NatureServe does not recognize this species (the GNR rank); instead it names it as Calystegia spithamaea ssp. stans.
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| Other Common Name(s) | Shale Bindweed | |
| State Rank | S2S3 | |
| Global Rank | G4G5T4 [G4] | |
| State Status | W1 [W7] | |
| US Status | | |
| USACE-agcp | | |
| USACE-emp | | |
