5. Isoëtes hypsophila Handel-Mazzetti, Symb. Sin. 6: 13. 1929.
高寒水韭 gao han shui jiu
Plants helophytic, small, less than 5 cm tall. Rhizome fleshy, tuberous, ca. 4 mm, 2- or 3-lobed. Microphylls (4-)6-10 tufted, spreading, bright green above base, linear, 3-4.5 cm, ca. 1 mm wide, succulent, herbaceous, apex acuminate, base broadly sheathlike, membranous, ca. 4 mm wide; peripheral fibrous bundles absent. Ligules cordate-ovate, ca. 1 mm. Megasporangia ca. 3 mm, ca. 2 mm in diam.; megaspores 300-400 μm in diam., proximal and distal hemispheres glabrous. Microsporangia ca. 2.5 mm, ca. 1.5 mm in diam.; microspores 18-22 μm, glabrous. Spores mature Jul-Aug. 2n = 22*.
● Shallow water in intermittent pools, margins of waters in drying pools in grazed or ungrazed meadows on sandy soil; 3500-4300 m. SW Sichuan (Daocheng, Hongyuan, Jiulong), NW Yunnan (Zhongdian).
The type of Iseotes hypsophila was collected on the way from Lijiang, Yunnan, to Xuyong, Sichuan, without accurate locality. This species could occur in Qinghai and Xizang.
This species has glabrous megaspores. Based on molecular data (Hoot et al., Syst. Bot. 31: 449-460. 2006), the Chinese species form a monophyletic clade with other E Australian/New Zealand/E Asian/New Guinean species, and Iseotes hypsophila is the first diverging lineage within this Chinese clade.