Spiranthes sinensis (Pers.) Ames

Plants up to 30-50 cm. Roots narrowly cylindric. Stem slightly flexuous, leafy below. Leaves erect-spreading, linear to lanceolate. Inflorescence with flowers on a spirally twisted, densely glandular-pubescent rachis, rarely arranged in a single row with the tendency of twisting, up to 10-15 cm long. Bracts ovate-lanceolate, the lower slightly exceeding the ovary. Flowers rose to rose-purple, rarely whitish, fragrant. Sepals lanceolate, up to 5 mm long, the dorsal forming a tube with the narrower petals and labellum. The latter sessile, obovate in outline, 4-5 mm long, somewhat constricted in the middle, basal section whitish, with 2 small glands on each side near the column, apical section rose-purple, ± pubescent, with the margin undulate-crispate. Column 2 mm long. Ovary sessile, cylindric-fusiform, bent at apex, ± densely glandular-pubescent.

Distribution: Widely distributed in the Himalaya region from the foot-hills up to 3700 m; S. E. Asia, E. Rossia, China, Japan, New Guinea, Australia, Tasmania, New Zealand.

Fl. Per.: May-September.

Flowering from July to August.

Spiranthes sinensis is occurring in Siberia, China, Japan, Indochina, India, Malay Peninsula and the Philippines southward to New Zealand and Tasmania.

Molecular variations of Spiranthes sinensis Ames var. australis (R.Br.) H. Hara et Kitam. ex Kitam. was examined using the trnL-F sequence. Sequence differences in S. sinensis var. australis from Sabah, Malaysia, clearly differed from that of Japanese S. sinensis var. australis, suggesting genetic heterogeneity of Spiranthes sinensis var. australis in Asia. Molecular analysis based on the sequences of nuclear ITS1 regions indicated that there are two major groups of S. sinensis var. australis in Japan, with a geographic distribution boundary on Kyushu Island (Tsukaya, 2005).

Plants 30-40 cm tall. Rhizome, bearing fascicle roots and leaves. Leaves linear-oblong, 5-15 cm long, becoming much longer in tall grass clumps, 5-8 mm wide, fleshy, apex acute, base truncate in radicle ones and attenuate in cauline ones, with 3 main veins, veinlets reticulate. Peduncle 1-4, glabrous, 10-35 cm tall, with 2-3 sterile bracts; rachis 5-15 cm long, with few to many spirally arranged flowers; floral bracts lanceolate. Flowers white or pink; ovary pale green, curved at apex; sepals narrowly lanceolate, 4.5-5 mm long, dorsal one concave at base, lateral ones oblique and slightly gibbose at base; petals oblanceolate, 3.5-4 mm long; lip separated from column base, oblong when expanded, concave and short clawed at base, bearing 2 clavate calli at each side, erect and slightly inflexed at middle, ovate or rounded at apex, apex recurved, with crispate margins, disc hairy; column erect, clavate, 1.8-2.1 mm long; anther broadly ovoid, 0.7 mm long; pollinia ca. 1mm long; stigma orbicular, slightly convex; rostellum thin, triangular-lanceolate, lower margins toothed; viscidium narrowly oblong.

The chromosomal number of Spiranthes sinensis is 2n = 30 (Terasaka et al., 1979; Martinez, 1985; Aoyama et al., 1992; Rudyka, 1995).

Growing in moist grasslands, roadsides, slopes, along rivers; below 3400 m.

Spiranthes sinensis, commonly known as the Chinese spiranthes, is a species of orchid occurring in eastern and southeastern Asia.

Spiranthes sinensis was long thought to be a species complex, and more than 30 names have been synonymized under it; recent molecular and morphological data found that the complex was composed of six distinct species. 'True' S. sinensis sensu stricto is glabrous, blooms in the spring, and has pale blush-pink flowers. This species had formerly been thought to occur throughout Asia and Australia, it is actually restricted to southeast Asia, eastern East Asia, and southern Japan. The other species to be recognized out of this species complex are Spiranthes australis, Spiranthes flexuosa, Spiranthes maokensis, Spiranthes sunii, and Spiranthes suishanensis.

Spiranthes sinensis