Pueraria grandiflora Bo Pan & Bing Liu, 2015

Pan, Bo, Liu, Bing, Yu, Zhi-Xiang & Yang, Yong-Qiong, 2015, Pueraria grandiflora (Fabaceae), a new species from Southwest China, Phytotaxa 203 (3), pp. 287-291 : 287-290

Pueraria grandiflora Bo Pan & Bing Liu , sp. nov. ( Fig. 1–2 )

Type:–– CHINA. Sichuan: Panzhihua Cycad Reserve, on montane slopes, 1500 m, 20 Aug. 2014, Bo Pan 2014001 (Holotype: HITBC! Isotypes: KUN!). Panzhihua Cycad Reserve, 1300 m, 16 Jul. 2010, Panzhihua Cycad Expedition Team 360 ( PE).

Liana 3–8 m long. Roots tuberous, ovoid in shape, elongate or compressed, 2.5–8 × 3–9 cm, 4 to many clustered underground. Stems usually woody at the base, with young parts grey pubescent, sometimes glabrescent. Leaves trifoliolate and alternate; stipules medifixed and split at the base, sagittate, 8–16 mm long, with striate lines; stipels linear-lanceolate, 5–8 mm; petioles 5–12 cm long with appressed, short hairs; petiolules 5–8 mm long; leaflets broad ovate or compressed ovate, entire or 2–3 lobed, veins 4–6 pairs, short pubescent on both surfaces; the terminal one 4–11 × 3–10.5 cm, base round or broad cuneate, apex acuminate; lateral leaflets oblique and sometimes very unequal ( Fig. 2N ), smaller, 3–10.5 × 3–9.5 cm, base broad cuneate to truncate. Inflorescences axillary or terminal pseudoracemes, unbranched or with 1 branch, 15–40 cm long, erect or slightly ascending; peduncle 4–14 cm, appressed hairy; pedicels ca. 7 mm in length. Flowers 3 per node, subtended with ovate bracts; bracts 4 per node, basifixed, long hairy the abaxial surface, 4–7 mm, caducous soon after flowering, the outer one is bigger than the other three each node ( Fig. 2I ). Bracteoles 2, ovate and striate, ca. 3 mm; petals 22–25 mm long; calyx 10 mm long, purplish grey, pubescent; calyx lobes 4, lanceolate, acuminate, with the upper two teeth completely fused, 5–6 mm long, slightly longer than the tube, the lower lobe slightly longer than the others. Corolla bicolored; standard obovate, white to light blue with a yellow patch in the middle, 22–25 mm, auriculate and with a pair of callosities at base, shortly clawed; wings purple-blue, darker than the standard, falcate, ca. 23 × 7 mm, base with linear auricles; keel like the wings in color, falcate-oblong, with very small and acute auricles, subequal with the wings; stamens 10, vexillary stamen connate with the other 9 in the middle, free at both ends; ovary linear, hairy. Fruits legumes, long-elliptic, ca. 5.5 cm × 10 mm, flattened, never twisted when ripe, 4–5 seeded, constricted between the seeds, densely brown hirsute. Seeds reniform, compressed, smooth and brown, ca. 4 × 2.5 mm; aril a short, circular rim around the hilium; funicle slender and terete, ca. 2 mm long.

Distribution and habitat: Pueraria grandiflora is currently known from dry-hot valleys along the Jinsha River and Red River in Sichuan and Yunnan, SW China ( Fig. 3 ), a very specialized habitat in East Himalaya and Hengduan Mountain. Dry-hot valley is characterized by arid or semi-arid climate, savanna vegetation, and strong foehn effect ( He et al., 2000). This liana creeps on mountain slopes, rocks, thickets, open places, or climbs into small trees. Its tubers store plenty of water, and help it survive the dry season. The elevation range is 700–1600 m.

Etymology: The species epithet refers to the large flowers of this species, the largest within the genus to date.

Phenology: Flowering from June to September, fruiting August to October. Leaves fall in winter.

Conservation Status: All the specimens are only known from 6 locations ( Fig. 3 ). According the IUCN (2001) redlist criteria, this species is considered data deficient (DD) due to the low number of collections. Further investigation into the range of this species would be required to more fully assess the conservation status.

Taxonomic notes: Pueraria grandiflora has the largest flower within this genus, 22–25 mm in length, while all other species have smaller flowers, 8–22 mm in length. P. grandiflora is most similar to P. tuberosa Candolle (1825) , as both have bunches of tubers. However, P. grandiflora differs in lobed leaflets, larger flowers, single or once branched inflorescences, and flowering July to September. P. grandiflora also resembles P. montana , which has both entire and lobed leaflets. P. montana var. thomsonii (Benth.) M.R. Almeida also has a very large flower, 18–22 mm in length. Roots of both P. tuberosa and P. montana are important traditional medicines ( Van der Maesen, 1985; Wu & Thulin, 2010). Potentially, the tubers of P. grandiflora could be a medicine.

Their differences are summarized below ( Table 1):

Additional specimens examined: CHINA. Sichuan:Jinyang County, Dengchang, Lugao, among roadside grasses, 700 m, 10 Sept. 1978, Sichuan Institution of Traditional Medicine 846 (SM). Yunnan: Luquan County, Wumeng, Lezuoni, in valley, 26°1 ′ N, 102°44 ′ E, 1100 m, 7 Jun. 1982, Heng Li et al., 20166 (KUN, HITBC). Luquan County, Pudu River Nature Reserve, Zhongping, dry and steep slope, 1170 m, 26°9 ′ 31.5 ″ N, 102°50 ′ 45.5 ″ E, 7 Aug. 2008, Hua Peng et al. 9910 (KUN). Chuxiong, Tuanshan, rocky slope, 1000 m, 17 Sept. 1939, Ming-Kang Li 31 (KUN). Yuanjiang, Dudu, 1100 m, 15 Sept. 2011, Jian-Wu Li 1007 (HITBC).

Figures

FIGURE 1. Pueraria grandiflora (from type locality). A. Habit. B. Flowers. C. Entire leaflets. D. Tubers. E. Tuber opened up. F. Sagittate stipule. G. Lobed leaflets. Photos by Bo Pan and Bing Liu.

FIGURE 2. Puerariagrandiflora. A. Calyx.B. Bracteoles.C. Bracts.D. Standard.E.Wing.F. Keel.G. Stamens.H. Pistil.I. Inflorescence. J. Tuberous roots. K. Flower. L. Pod. M. Flowering branch. N. Seed. O. Leaf with entire leaflets. Illustrations by Bo Pan.

FIGURE 3. Distribution of Pueraria grandiflora. Map by Shu-Feng Li.