Article from Bean's Trees and Shrubs Hardy in the British Isles
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'Periploca sepium' from the website Trees and Shrubs Online (treesandshrubsonline.
A deciduous climbing shrub 6 to 10 ft (perhaps more) high; young shoots glabrous. Leaves opposite, lanceolate to narrowly oval, not toothed, mostly slenderly pointed, tapered at the base, 13⁄4 to 4 in. long, 1⁄2 to 11⁄4 in. wide, shining green, glabrous on both surfaces; stalk 1⁄8 to 1⁄2 in. long. Flowers fragrant, about 3⁄4 in. wide, produced two to nine together in axillary and terminal cymes during June and July; main flower-stalk 1 to 2 in. long. Corolla greenish outside, dark purple inside, five-lobed, the lobes revolute and woolly towards the margin. Seed-pods in pairs, slenderly cylindrical, tapering at the end where they are connected, 4 to 6 in. long, 3⁄16 in. wide; seeds furnished with a tuft of silky white hairs.
Native of N. China; introduced to America in 1905. It differs from P. graeca in its narrower, often lanceolate leaves, more slender stems and somewhat hardier constitution. A further distinction given by Dr Browicz is that the corolla-lobes have a prominent glandular patch on the inner surface near the midpoint, absent in P. graeca.