PLANT: herbs with rhizomatous, twining stems, angular in cross-section, glabrous. LEAVES: ovate to ovate-lanceolate, glabrous, 2-15 cm long, 1-9 cm wide, basally cordate-sagittate to hastate, 5-nerved, the auricles obtuse to acute or 2-3 dentate, rarely 2-lobed, apically acute to acuminate, the border entire or undulate; petioles 2-7 cm long. INFLORESCENCE: of solitary flowers, on peduncles 3-13 cm long; bracts surrounding calyx angular-sulcate, ovate, convex, glabrous or ciliate, foliacous, the borders at times pinkish, 14-26 mm long, 10-18 mm wide, mucronate, mostly acute, the pedicels absent. FLOWERS: sepals elliptic to ovate-lanceolate, subequal, 11-15 mm long, 4-6 mm wide, thin, transparent, acute to almost obtuse, mucronate, apically ciliate; corollas funnelform, white or tinged on limb with rose orpink, 4.5-5.8 cm long; stamens 23-29 mm long, almost equal, basally glandular pubescent; style 20-23 mm long. FRUITS: capsular, 10-13 mm in diameter, ovoid, accompanied and partly surrounded by the enlarged bracts, which reach 30-35 mm long. SEEDS: 4.5-5 mm long, black, glabrous, smooth or granulose. NOTES: Moist habitats, near streams, elsewhere in thickets and fence rows: Cochise Co.; 1127 m. (3700 ft.); Jun-Aug; MA to WA, NC to AZ. As pointed out by Holmgren (1984) for the west, the subspecies is uncommon throughout its range. Through much of its range, this species may be confused with C. silvatica (Kitaibel) Grisebach. Living plants are easily separated. Calystegia silvatica has saccate calices, whereas C. sepium has calices that are more tightly appressed. Leaves are, however, the best way to distinguish the two species. Calystegia sepium and C. macounii have a clear V- or U-shape to the base of the leaf blade where the petiole attaches and in C. silvatica the blade base is quadrate. These differences are harder to see in pressed material, but can be detected with a little practice. Overall, leaf shape and pubescence are perhaps the easiest way to separate C. sepium from other species in the genus. REFERENCES: Austin, Daniel F. Southwestern 2006. Convolvulaceae. CANOTIA 2 (3): 79-106.