Calystegia sepium is a species of bindweed, with a subcosmopolitan distribution throughout the temperate Northern and Southern hemispheres. It is an herbaceous perennial that twines around other plants, in a counter-clockwise direction, to a height of up to 2–4 m, rarely 5 m. The palemattegreen leaves are arranged spirally, simple, pointed at the tip and arrowhead shaped, 5–10 cm long and 3–7 cm broad. The flowers are white, or pale pink with five darker stripes, produced from late spring to the end of summer. In the bud, they are covered by large bracts which remain but scarcely overlap and do not cover the sepals of the open flower. The open flowers are trumpet-shaped, 3–7 cm diameter, white, or pale pink with white stripes. After flowering the fruit develops as an almost spherical capsule 1 cm diameter containing two to four large, black seeds that are shaped like quartered oranges. The seeds disperse and thrive in fields, borders, roadsides and open woods. Several regional subspecies have been described, but they are not considered distinct by all authorities:
Calystegia sepium subsp. spectabilis. Siberia. Flowers often pinkish.
Other vernacular names include greater bindweed, bearbind, hedge convolvulus, hooded bindweed, old man's nightcap, wild morning glory, bride's gown, wedlock, white witches hat, belle of the ball. A common childhood pastime in the UK is to 'pop' the flowers from the sepals while chanting "Granny, granny — pop out of bed".
Eradication
Calystegia sepium is a plant with showy white flowers. However, because of its quick growth, clinging vines and broad leaves, it can overwhelm and pull down cultivated plants including shrubs and small trees. It's aggressively self-seeding and the success of its creeping rhizomes cause it to be a persistent weed and have led to its classification as a noxious weed.
Similar species
Calystegia silvatica, giant bindweed, is sometimes treated as a subspecies of C. sepium
Convolvulus arvensis, Field Bindweed, is a similar vine with much smaller features. The rear margin leaf projections are sharp.
The leaves of Ipomoea pandurata, Wild Potato Vine, are shaped like a heart, not like an arrowhead.
