Eutrema giganteum G.Q. Hao, Al-Shehbaz & J. Quan Liu, 2017

Hao, Guoqian, Zhang, Changbing, AL-Shehbaz, Ihsan A., Guo, Xinyi, Bi, Hao, Wang, Junyin & Liu, Jianquan, 2017, Eutrema giganteum (Brassicaceae), a new species from Sichuan, southwest China, PhytoKeys 82, pp. 15-26 : 18-21

Eutrema giganteum G.Q. Hao, Al-Shehbaz & J. Quan Liu sp. nov.

Type.

China. Sichuan: Dayi County, Xiling Snow Mountain, Heishuihe Giant Panda Nature Reserve , 30°40'22"N, 103°9'47"E, 2340 m, 6 July 2015, J.Quan Liu & G. Q. Hao 2015032-1 (Holotype, SZ)., J.Quan Liu & G. Q. Hao 2015032-2 (Isotype, SZ), J.Quan Liu & G. Q. Hao 2015032-3 (Isotype, SZ). Figure 1 .

Etymology.

The specific epithet refers to the remarkably huge plant size. The erect stem can extend to around 60-110 (-140) cm, higher than all the other Eutrema species.

Description.

Herbs, perennial, glabrous or sparsely pilose on upper parts; rhizome fleshy, to 2 cm in diam. Stems 60-110(-140) cm tall, robust, to ca. 1 cm diam, erect or ascending, simple at base, alternately branched above; branches 1-leaved, divaricate-ascending or almost perpendicular to stem. Basal leaves rosulate; petiole with a groove, hollow, cylindrical, (12-)15-26 (-35) cm; leaf blade cordate, (18-)25-35(-40) × (15-)20-30(-35) cm, margin dentate, denticulate or repand, with distinct apiculate callosities terminating ultimate veins, apex subacute to acuminate; cauline leaves with petioles gradually shorter upward, cordate to lanceolate, lowermost cauline 6-10 × 3-7 cm, gradually reduced in size upward. Racemes ebracteate, lax, elongated in fruit, main branch 20-30 cm; fruiting pedicels slender, reflexed or spreading, 0.6-1.5(- 2.2) cm. Sepals ovate or oblong, 1.5-2 × ca. 1 mm, deciduous; petals white, oblong-spatulate, 3.5-5(-7) × 1.5-2 mm, apex obtuse to rounded; claw present; filaments white, 3-4.5 mm; ovules 1-4 per ovary. Fruit dehiscent silicles, narrowly oblong, 5-8 × 2-3 mm, curved, not torulose; valves with an obscure midvein; gynophore absent or obsolete, septum complete. Seeds oblong, 2.5-3.5 × 1.5-2.0 mm.

Phenology.

Flowering: April-July; fruiting: May-August.

Distribution and habitat.

Eutrema giganteum is currently known from Hengduan Mountains in western Sichuan, China, including Xiling Snow Mountain, Jiajin Mountain, Erlang Mountain, and Gongga Mountain (Fig. 2 ). It grows in shady, humid forests at elevation of 2200-2900 m.

Additional specimens examined

(paratype). China: Sichuan: Baoxing County, 1954, Z. P. Song 38379 (KUN); Baoxing County, Puxi Gou , April 1959, 2700 m , Sichuan Economic Plant Investigation Team 00324 (CDBI); Luding County, Dawanzi , 2300 m, 2 May 1980, Q. Q. Wang 22061 (CDBI); Dayi County , Heishuihe Nature Reserve , 2900 m, 6 June 2007, D. H. Zhu, Z. B. Feng, C. Zhang & F. Wang 20070659 (PE) .

Figures

Figure 1. Eutrema giganteum G. Q. Hao, Al-Shehbaz & J. Quan Liu. sp. nov. A-B Habit C Leaves D Inflorescence E Flowers F Fruit.

Figure 2. Geographical distribution of Eutrema giganteum (P 1 - P 4) and Eutrema yunnanense (P 5, P 6). P 1 = Population from Xiling Snow Mountain, Sichuan; P 2 = Specimens record from Baoxing County, Sichuan; P 3 = Population from Erlang Mountain, Sihuan; P 4 = Population from Gongga Mountain, Sichuan; P 5 = Population from Haba Mountain, Yunnan; P 6 = Population from Cangshan Mountain, Yunnan,