Japanese Bindweed (Calystegia pubescens) — identification, habitat & look-alikes

Japanese bindweed is an East Asian vine in the morning glory family with pale pink, funnel-shaped flowers. In the US it's best known as California rose, a double-flowered garden form that sometimes escapes along roadsides and railroads, mostly in the Northeast and Midwest.

Appearance

Growth form: A perennial twining vine that spreads by underground . The stems die back each year and regrow in spring.
Leaves: Alternate on long stalks, long and narrow, with ear-like lobes at the base.
Flowers: One pale pink funnel per stalk, about 2–2.4 in (5–6 cm) across in Japan, with large green hugging the base. Each flower stays open through the day and lasts only one day.
Flowering time: June–August in Japan and Korea. Escaped plants in the northeastern US have been recorded blooming August–October.

Look-alikes

Hedge bindweedCalystegia sepium

Size alone doesn't settle it: hedge bindweed's flowers and bracts run about 1.5–2.75 in (4–7 cm), and Japanese bindweed's flowers in Japan are about 2–2.4 in (5–6 cm). A fluffy double pink flower points to California rose.

Why they get mixed upSame genus, same pink-to-white funnel flowers wrapped in big bracts.

Field bindweedConvolvulus arvensis

Field bindweed has tiny bracts partway down the flower stalk. Japanese bindweed has large bracts wrapped right around the base of the flower.

Why they get mixed upBoth are twining weeds with pinkish funnel flowers.

Black bindweedFallopia convolvulus

Black bindweed's flowers are tiny, green, petal-less, and easy to overlook, nothing like a showy pink funnel.

Why they get mixed upBoth are twining vines with arrowhead-shaped leaves, and 'bindweed' is in both names.

Where it lives

Typical habitats: roadsides
railroad edges
gardens
Range: Native to Japan, Korea, and China. In the US it shows up mainly as a garden escape in the Northeast and Midwest, from Wisconsin and Illinois eastward and from Tennessee and North Carolina northward.
Preferred conditions: Handles most soils and likes moist ground, but doesn't do well in shade.
Flowering: Flowers Aug–Oct
Flowers Aug–Oct

Life cycle

Reproduction: Seed is rare. The plant can't fertilize itself, so it spreads mostly through its roots and creeping stems.

Name and classification

About the name: Some American botanists include the smaller-flowered Japanese false bindweed (Calystegia hederacea) in this species and use that name for both, so US descriptions and ranges may mix the two.
Varieties and forms: California rose is the double-flowered form, with fluffy, many-petaled pink flowers. It's grown in gardens and occasionally escapes.