六叶葎 liu ye lü

Asperula hoffmeisteri Klotzsch, Bot. Ergebn. Reise Waldemar, 87. 1862; Galium asperuloides Edgeworth subsp. hoffmeisteri (Klotzsch) H. Hara; G. asperuloides var. hoffmeisteri (Klotzsch) Handel-Mazzetti; G. asperulopsis H. J. P. Winkler; G. japonicum Makino (1895), not (Maximowicz) Makino & Nakai (1908); G. triflorum Michaux var. hoffmeisteri (Klotzsch) J. D. Hooker.

Herbs, perennial, from filiform reddish rhizomes. Stems generally erect, (10-)15-30(-40) cm tall, 4-angled, glabrous and smooth, sometimes hispidulous at nodes. Middle stem leaves and leaflike stipules in whorls of up to 6 (in weak plants rarely only up to 4), with petioles up to 3 mm; blade drying papery or membranous, narrowly elliptic-oblong to broadly oblanceolate, (10-)15-30(-40) × (4-)5-10(-12) mm, length/breadth index mostly 2.5-3.5, glabrescent, smooth or rarely retrorsely aculeolate on abaxial midrib, base acute to obtuse, margins antrorsely aculeolate, apex obtuse to rounded and abruptly apiculate; vein 1. Inflorescences terminal and sometimes in axils of upper leaves, with few- to several-flowered cymes; peduncles glabrous, smooth; bracts none or few, 1-2 mm; pedicels 0.3-3 mm. Ovary obovoid to subglobose, 0.5-0.8 mm, strigillose with undeveloped trichomes. Corolla white or light green, rotate, 2.5-3 mm in diam., glabrescent, lobed for 3/4 or more; lobes 4, ovate, acute. Mericarps ellipsoid, 1.2-2 mm, with dense uncinate trichomes 0.8-1.2 mm, on pedicels elongating and up to 10 mm. Fl. Apr-Aug, fr. May-Sep.

Forests on mountain slopes, thickets, along rivers, ditch sides, meadows; 400-4000 m. Anhui, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Shanxi, Sichuan, Xizang, Yunnan, Zhejiang [Afghanistan, Bhutan, India, ?Japan, Kashmir, Korea, Myanmar, Nepal, Pakistan].

Galium hoffmeisteri, together with G. bungei, G. spurium, and G. verum, is one of the most commonly collected species of Galium in China. Previous authors usually have included it as a subspecies under G. asperuloides. Only recently, the two taxa were discussed and re-established on the species level by Ehrendorfer et al. (Fl. Iranica 176: 183-185. 2005) and by Mill (loc. cit.). All specimens seen so far from China belong to G. hoffmeisteri. Nevertheless, as G. asperuloides s.s. ranges in the W Himalaya from Afghanistan to N Pakistan and N India, it can also be expected in SW China (in particular, Xizang). Accordingly, it is included in the present treatment for reference.

In Japan Galium hoffmeisteri is replaced by G. nipponicum Makino (G. trifloriforme var. nipponicum (Makino) Nakai), but some of the Japanese specimens greatly approach G. hoffmeisteri. Another very similar vicariant is G. echinocarpum from Taiwan. Further relatives are the Eurasian disjunct G. odoratum and the circumboreal G. triflorum. Together with G. asperuloides, all these taxa belong to G. sect. Hylaea as shown by Ehrendorfer et al. (loc. cit.: 181-185). Galium triflorum is rare in China and closely related to G. trifloriforme (see under these species). The latter may be a hybridogenous taxon linking G. sect. Hylaea and G. sect. Trachygalium. But to synonymize G. trifloriforme with G. hoffmeisteri (e.g., W. C. Chen in FRPS 71(2): 230. 1999; Govaerts et al., World Checkl. Rubiaceae; http://www.kew.org/wcsp/ rubiaceae/; accessed on 15 Sep 2010) is certainly not correct.

Slender plants of Galium hoffmeisteri are distantly reminiscent of G. kikumugura Ohwi (= G. brachypodum Maximowicz (1874), not Jordan (1846)) from Japan (see also under G. sichuanense). Yamazaki (Fl. Japan 3a: 236. 1993) described G. kikumugura as having leaf whorls of 4. In reality, it always develops whorls of up to 5 or 6 in the middle stem region. These leaves are quite similar to those of G. hoffmeisteri and have margins slightly antrorsely aculeolate or smooth. Nevertheless, G. kikumugura strongly deviates from G. hoffmeisteri and other members of G. sect. Hylaea by its cymes nearly exclusively lateral in leaf axils, usually consisting only of a filiform peduncle, a single bract, and 2 small flowers (ca. 1.5 mm in diam.) or sometimes a single flower. Furthermore, its kidney-shaped (not ellipsoid) mericarps (1.8-2 × 0.9-1 mm) differ by having scattered short and hooked hairs only ca. 0.1 mm. These latter characters are reminiscent of G. sect. Trachygalium and particularly of G. bungei (in G. sect. Platygalium s.l., where leaf whorls have only 4 elements). Thus, G. kikumugura is an isolated and aberrant species of the genus, possibly better placed into a separate monotypic section.