2. Calystegia pubescens Lindl. (Japanese bindweed)
Convolvulus
pellitus Ledeb. f. anestius
Fernald
Map 1578
Stems mostly 30–200
cm long, scrambling or trailing, twining, at least toward the tip, glabrous or
more commonly sparsely pubescent with short hairs. Leaves short- to less
commonly long-petiolate, usually sparsely pubescent with short hairs, the
petiole usually less than 1/2 as long as the midvein of the accompanying leaf
blade. Leaf blades 2–8 cm long, oblong to narrowly ovate-triangular, narrowed
to a bluntly or more commonly sharply pointed tip, deeply cordate at the base,
the sinus U-shaped or occasionally V-shaped, the basal lobes often each with 1
or 2 additional shallow lobes along the upper portion, spreading, angular,
mostly sharply pointed. Flowers solitary or less commonly paired in the axils
of leaves, positioned mostly above the stem midpoint. Bracts 15–21 mm long,
usually overlapping only toward the base, not strongly inflated (usually
appearing somewhat angular), ovate to oblong-ovate, rounded to bluntly pointed
at the tip, usually glabrous. Sepals 8–10 mm long, ovate to oblong-ovate.
Corollas doubled (at least in Missouri material), 2.5–4.0 cm long, pink. Fruits
not produced. 2n=22. May–September.
Introduced,
uncommon and widely scattered, mostly in and around urban areas (native of
Asia; introduced sporadically in the eastern U.S. west to Iowa, Idaho, and
Canada). Fallow fields, gardens, roadsides, railroads, and open, disturbed
areas.
Missouri plants
were included in the circumscription of Convolvulus pellitus f. anestius,
which was based upon a sterile cultivar with doubled flowers (sometimes known
as California rose). Presumably they escape from ornamental plantings via
fragments of roots or stems. The correct species determination of this cultivar
has been controversial. It has been classified variously under Calystegia
pellita (Ledeb.) G. Don, C. hederacea Wall., C. dahurica
(Herb.) Choisy, and C. pubescens, and under Convolvulus japonicus
Thunb. (non Choisy) and C. wallichianus Spreng. The present assignment
follows that of Fang and Brummitt (1995) in the recent Convolvulaceae treatment
for the Flora of China series.