Chamaesium novemjugum (C. B. Clark) Norman (1938: 231)

Guo, Xian-Lin, Tan, Jin-Bo, Hu, Hao-Yu, Yu, Huan-Xi & He, Xing-Jin, 2017, Morphological and micromorphological data support the independent specific status of Chamaesium spatuliferum (Apioideae, Apiaceae) from China, Phytotaxa 314 (1), pp. 81-88 : 84-85

Chamaesium novemjugum (C. B. Clark) Norman (1938: 231)

Basionym:— Trachydium novemjugum Clarke (1879: 672) .

Lectotype (designated here!):— INDIA. Sikkim: 12000–15000 ft (about 3600–4500 m), J. D. Hooker. 672 (Lectotype: K000697397 !, Fig. 2A ; isolectotype: K000697398 !, Fig. 2B ).

Clarke (l.c.) questionably assigned this species to Trachydium because he considered the radical leaves to be like Trachydium . Later, after a critical study, Norman (1938) assigned the species to Chamaesium . In the protologue, Clarke mentioned only “J. D. Hooker, Sikkim, alt. 12000–15000 ft ”. There are two sheets in the Hooker herbarium at K (nos. K000697397 and K000697398) that bear these words and both appear to be original material. The lectotype designated above, matches more closely the protologue description and therefore is selected as lectotype.

Description:—Stem shortened, plants usually acaulous. Leaves basal pinnate, petioles 1.5–5 cm, sheaths long, broad; blade oblong, 3–10 × 1–2 cm, pinnate, pinnae sessile, 1–5 pairs; ultimate segments broad-ovate or rhombus, 5–10 × 3–8 mm, reticulate-nerved, base subtruncate or rounded, 3–8-toothed, terminal pinnae obovate or orbicular, base cuneate, apex more deeply 3-lobed. Umbels often subsessile. Rays 15–20, 4–8 cm, thick, often hollow; Petal lurid green.Bracts like reduced leaves with narrower pinnate, bracteoles linear-obovate, toothed lobed or subpinnatifid. Styles very small. Fruit oblong to ovoid, subquadrate, somewhat cordate at the base, slightly narrowed close under the calyx margin which is wider than the summit of the fruit, Calyx teeth trilateral; Style bases depressed, inconspicuous. Carpels semi-terete; primary and secondary ridges prominent, hollow, smooth.

Distribution and habitat:—The species is distributed to China, India and Butan. It grows on the swamp meadow at altitudes of 4200–4800 m.

Note:— Chamaesium novemjugum shares a number of morphological characteristics with C.spatuliferum such as shortened stem,stout roots and pinnate bracts. However, C. novemjugum possesses more lobes on the margin of segments and more obvious veins on adaxial leaf surface, and In addition, the results of LM and SEM observations indicate that micromorphological characters, such as the shape of calyx, the shape of fruits, the surface ornamentation of pericarp, are strikly different from each other. C. novemjugum usually possess oblong pericarp with trilateral calyx teeth and striped surface, unconsipious cell contour, regular cells and sinuous anticlinal walls, however, C. spatuliferum have ellipsoid fruits with minute calyx teeth and smooth surface, conspicious cell contour, polygonal cells and straight anticlinal walls on adaxial and abaxial surface of leaves,. Additionally, ongoing phylogenetic analysis of this genus also supports to treat of these two taxa as separate species (unpubl. data).

Additional specimens examined: China. Xizang: Nyingchi Xian, Pass Segrile , 17 September 1980, Ecological Institute & Plateau Institute 15655 ( PE) ; Nyingchi Xian, Pass Segrile , 4200 m, 5 September 2015, X. L. Guo & H. X. Yu gxl201509050101 ( SZ) ; Nyingchi Xian, South of Pass Segrile , 17 September 1980, Z. C. Ni, Y. Z. Wang, D. Ci & D. Ci 1726 ( PE) ; Nyingchi Xian, Pass Segrile , 4 August 1983, B. S. Li & S. Z. Cheng 06085 ( PE) ; Yadong Xian, Pali , 4600 m, 20 September 1974, Qingzang Team 2705 ( KUN) ; Yadong Xian, Pali , 4200 m, 23 August 2016, X. L. Guo, J. Bai & C. Peng gxl201608230101( SZ) .

Figures

FIGURE 2. Clark 672, Lectotype of Chamaesium novemjugum. A. lectotype; B. isolectotype.