A small shrub with slender pendulous or prostrate branches; stems glabrous or downy. Leaves oblong-ovate or lanceolate, mostly 2 to 31⁄2 in. long, shortly toothed, bright green above, paler and usually slightly downy on the veins beneath; leaf-stalks less than 1⁄2 in. long. Corymbs up to 3 in. across, borne terminally on short, leafy axillary shoots. Ray-flowers few, 3⁄4 to 11⁄2 in. wide, with white or blue saw-toothed sepals; fertile flowers with obovate clawed petals. Capsules half-enclosed in the calyx-tube. Seeds not tailed.
Native of southern Japan. This species is scarccly known in this country and nothing can be said about its garden value, though it would seem to be worthy of introduction. According to previous editions of this work it was cultivated at Rostrevor in Co. Down by Sir John Ross of Bladensburg.
A curious form of H. scandens has been described by the Japanese botanist Koidzumi under the name H. luteovenosa. It is distinguished by its very small leaves (mostly 1 to 13⁄8 in. long, 3⁄8 to 3⁄4 in. wide), which are blotched or veined with yellow. It apparently occurs wild in Japan and is not a cultivar. It has been identified by Miss McClintock with H. liukiuensis Nakai from the Ryukyu Islands, described earlier and treated by her as a subspecies of H. scandens.
subsp. chinensis (Maxim.) McClintock H. chinensis Maxim.; H. davidii Franch.; H. umbellata Rehd. – This subspecies has a wide range in E. Asia outside Japan. It differs from the typical subspecies described above in its taller growth, its larger and more leathery leaves 2 to 6 in. long, 1⁄2 to 21⁄4 in. wide (against 13⁄8 to 3 in. by 5⁄8 to 11⁄4 in. in typical H. scandens) and its larger inflorescences, which are 3 to (mostly) 4 to 6 in. wide (against 13⁄4 to 3 in.). The leaves may be downy on the veins beneath or almost glabrous. This hydrangea was at one time in cultivation from seeds sent by Wilson from W. China in 1908 and grown under the name H. davidii. This introduction flowered in June and July and had the fertile flowers blue and the sterile ones white.