44. Galium rupifragum Ehrendorfer, Novon. 20: 273. 2010.
屏边拉拉藤 ping bian la la teng
Herbs, perennial, densely caespitose, emerging from a slender branching rootstock; all vegetative parts very fragile when dried and with a loose indumentum of soft hairs, 0.5-0.8 mm, ± straight and spreading, on upper leaf surface slightly retrorse. Stems ascending or erect, 5-10 cm tall, 4-angled, hairy, with 12-18 internodes, increasing in length from 2-8(-15) mm upward, with some short vegetative lateral branches from middle region to inflorescence base. Leaves in whorls of 4; blade thinly papery and remaining ± greenish when dried, ovate to broadly lanceolate, 5-8 × 2.5-3.5 mm, loosely hairy on both sides and marginally, base attenuate, margins flat or slightly revolute, apex acute to apiculate; principal veins 3, palmate, lateral weak. Inflorescences terminal, often with 3 cymes, each with 3-5 flowers; bracts few and ± reduced; peduncles 4-5 mm and pedicels 0.5-3 mm, glabrescent, somewhat elongated and divaricate in fruit. Flowers hermaphroditic. Ovary ovoid, ca. 0.5 × 0.3 mm, with still undeveloped appressed hairs. Corolla greenish white, rotate, ca. 1.5 mm in diam., with 4 triangular and acute to slightly apiculate lobes. Mericarps 0.8-1 mm, with spreading uncinate trichomes ca. 0.25 mm. Fl. and fr. Jul-Sep.
● Mountain regions, on rocks; ca. 1800 m. Yunnan (Pingbian).
The above description of Galium rupifragum is based on two sheets collected by H. T. Tsai (H. T. Tsai 60986) on rocks at the type locality and deposited in PE. Galium rupifragum belongs to G. sect. Platygalium s.l. and exhibits affinities with the G. bungei group, in particular with G. salwinense. Both share slender growth and uncinate fruit hairs. But G. salwinense has fewer (only up to 10) and longer (up to 10-20 mm) stem internodes, smaller leaves, only 1 (and not 3) main leaf veins, and smaller flowers. Nevertheless, on Emei Shan (Sichuan) typical G. salwinense occurs at lower elevations, whereas at higher elevations reduced forms approach G. rupifragum. In addition, there are also obvious similarities between G. rupifragum and representatives of the G. morii group (see there), growing with five accepted species in the high mountains of Taiwan, particularly with G. morii itself and with the related G. formosense. Main differences from the latter are its lower growth and smaller leaves, from the former its hirsute stems and the more divaricate, often longer peduncles and pedicels.