Saussurea yui Y. S. Chen, 2015

Chen, You-Sheng & Yuan, Qian, 2015, Twenty-six new species of Saussurea (Asteraceae, Cardueae) from the Qinghai-Tibetan Plateau and adjacent regions, Phytotaxa 213 (3), pp. 159-211 : 176-177

9. Saussurea yui Y. S. Chen , sp. nov. (Fig. 9)

Type:— CHINA. Sichuan: Muli County, Wachin Xiang , Jin-chang , on rocks in woods, 4100 m, 20 October 1937, T. T. Yu 14673 (holotype PE; isotypes A, KUN) .

Herbs perennial, usually nearly stemless or rarely with short stem up to 10 cm. Rhizomes ascending, branched or simple, densely covered with dark brown residue of old leaves, with numerous or a few blackish brown stout roots of even thickness. Leaves rosulate or cauline, subsessile; leaf blade green on both surfaces, oblong to narrowly elliptic, (2.4–) 4–9 cm long, (0.4–) 0.7–1.8 cm wide, chartaceous, glabrous, midveins conspicuous, base cuneate-attenuate, margin obscurely denticulate or entire, apex acute or obtuse. Capitula solitary in rosette of leaves at end of stem, sessile. Involure subglobose, 1.4–2.5 cm in diameter and 1.5–2.5 cm high. Phyllaries in 5–6 rows, imbricate, leathery, abaxially sparsely pubescent or nearly glabrous; outer and middle phyllaries oblong, 10–15 mm long, 5–7 mm wide, apex obtuse; inner phyllaries elliptic, 15–20 mm long, 3–4 mm wide, apex narrowly obtuse. Receptacle flat, densely covered with persistent yellowish bristles, bristles linear, 6–7 mm long. Corolla purplish blue, 15–19 mm long, tubular-funnelform, glabrous, tube 7–12 mm long, limb 6–8 mm long, lobes 3–4 mm long. Anthers ca. 8 mm long including tails; tails lanate, ca. 1 mm long. Achenes cylindroid, 4–5 mm long, ca. 1.5 mm wide, ribbed, glabrous. Pappus yellowish white; outer bristles 3–4 mm long, scabrid; inner bristles 14–18, plumose, 13–16 mm long.

Distribution and habitat:— Saussurea yui is currently known only from Muli County, southwestern Sichuan, China. It grows in grassy slopes, thickets or on rocks in Quercus forests at altitudes of (2800–) 3800–4200 m.

Phenology:—Flowering and fruiting from September to October.

Etymology:—The specific epithet is derived from the name of the famous Chinese collector and distinct taxonomist, T. T. Yu. Chinese name: ĞŐṈLẄ.

Additional specimens examined (paratypes):— CHINA. Sichuan: Muli County, Wachin, Jin-chang , on surface of rocks, 4100 m, 29 October 1937, T. T. Yu 14677 ( A, PE) ; Muli County, Chenchang , in thickets and grassy slopes, 4200 m, 13 September 1983, Qinghai-Xizang Expedition 14012 ( PE) ; Muli County, Chenchang , in Quercus forests, 3800–4000 m, 13 September 1983, Qinghai-Xizang Expedition 14011 ( KUN) ; Muli County, near Ngerya, Lamachang , on the border of Chungtien , 2800 m, on open hillside, 30 August 1939, K. M. Feng 2863 ( A, PE, KUN) ; Yanyuan County, Wodi, north slope of Huolu Shan , on rocks at forest margin, 4000 m, 29 July 2011, Y. S. Chen & Y. C. Bi 11-078 ( PE) .

Discussion:— Saussurea yui belongs to S. subgen. Saussurea sect. Gymnocline because of its habit nearly stemless, leaves nearly entire and capitula solitary. An isotype specimen of S. yui in the Havard Univeristy Herbarium had been previously misidentified as S. superba Anthony (1934: 212) by Lipschitz. It is similar to S. superba in the habit, leaf shape and solitary capitula, but differs by its rhizome with blackish brown stout roots of even thickness (vs. roots uneven and slender), leaves glabrous and blade oblong to narrowly elliptic, midvein narrower (vs. densely villous, blade ovate-oblong, midvein distinct), and phyllaries in 5–6 series, sparsely pubescent or nearly glabrous, apex obtuse, margin green (vs. in 4–5 series, glabrous, apex acuminate, margin blackish brown), and inner pappus 13–16 mm long (vs. 15–18 mm long).

In our molecular tree, S. yui is shown to be closely related to S. ciliaris Franchet (1888: 337) , S. montana Anthony (1934: 208) and S. poochlamys Handel-Mazzetti (1925: 15) . In fact, it is very similar to S. ciliaris in the habit, fibrous roots of even stout and phyllary shape and texture, but it differs by its receptacle densely covered with persistent and distinct bristles 6–7 mm long (vs. receptacle naked), phyllaries in 5–6 series (vs. in 4–5 series), and leaf blade 1–1.8 cm wide and margin usually obscurely toothed (vs. 0.3–1.2 cm wide, margin entire and revolute), phyllary apex obtuse (vs. acute), and inner pappus 13–16 mm long (vs. 12–13 mm long). A comparison of S. yui with related species is given in Table 8.