欧旋花 ou xuan hua

Calystegia dahurica (Herbert) G. Don; ?Calystegia sepium (Linnaeus) R. Brown var. integrifolia Liou & Ling; Convolvulus dahuricus Herbert.

Stems climbing to several meters tall, glabrous or pubescent. Petiole 2--8 cm; leaf blade ± triangular with basal lobes 1/3--1/2 X as long as the midvein, glabrous to sparsely pubescent; sinus with divergent sides. Peduncles not exceeding leaf; bracteoles to 3 X 2.2 cm, keeled to somewhat saccate at base and slightly overlapping, apex acute to ± obtuse. Corolla pink, (4.5--)5.5--6.5 cm. Stamens (2.2--)2.5--3 cm; anthers 5.5--6.5 mm. Fl. Jun-Aug, fr. Sep.

Waste places, river banks. Beijing Shi, ?Heilongjiang, Jilin, Liaoning, ?Tianjin Shi [Japan, ?Korea, Russia; introduced in N Europe]

Calystegia sepium is a widespread and highly polymorphic species with a number of subspecies recognized in temperate parts of the northern and southern hemispheres.

Calystegia sepium subsp. spectabilis was described from a plant naturalized in northern Europe, the native provenance of which is uncertain. The relationships of this to the plants from China and northern Russia, and also to C. pulchra Brummitt & Heywood, which was also described from a plant naturalized in northern Europe, are uncertain. The material from China and adjacent Russia is relatively uniform. It has larger and more inflated bracteoles and larger flowers than most subspecies of C. sepium, in this respect coming close to C. silvatica (Kitaibel) Grisebach, but it is apparently always pink flowered. A similarity to C. sepium subsp. appalachiana Brummitt, from the eastern U.S.A., should also be noted.

Calystegia sepium subsp. spectabilis intergrades into C. pubescens in N Korea and N Japan, and intermediates with C. pellita (Ledebour) G. Don are found in N China.

Calystegia dahurica (Herbert) G. Don is probably referable here, but the provenance of the original plant is unknown. No type specimen has been traced, and the name can only be typified by a rather inadequate original illustration.