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Plants of Taiwan

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    台灣植物誌 第一版  Flora of Taiwan, 1st edition    Vol. 1

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    台灣植物誌第一版  Flora of Taiwan, 1st edition  1: 53


    4. ISOETACEAE
    CHARLES E. DEVOL
    Usually aquatic perennials, growing submersed, emersed or rarely terrestrial; stem corm-like, 24 lobed giving rise to numerous dichotomously branching roots and a tuft of elongated grass-like leaves. Leaves with 4 longitudinal air-channels and a central vascular strand, some species with peripheral vascular strands, many species with stomata. Sporangia large, borne at base of sporophylls, containing either large tetrahedral megaspores, or minute ellipsoidal microspores; ligule borne above sporangium; a thin velum often more or less covering the sporangium; basal portion of sporophylls expanded, winged. Megaspores white, gray or black, smooth, warty, echinate or reticulate.
    A family with only one genus.
    1. ISOETES L.
    Characters of the family.
    About 100 species, and many varieties, only one species in Taiwan.
    1. Isoetes taiwanensis DeVol in Taiwania 17(1): 1 & (2): 304. 1972. xW Pl. 11
    Corms 34 lobed. Leaves widely spreading, 7 to 24 cm long, in tufts of 15 to 90 or more, flattened on upper side, rounded on lower side, the base expanded with membranaceous margins, with scattered stomata near the tips, peripheral fibers absent; ligule elongate, triangular; velum rudimentary, only covering top of the sporangium. Megasporangium oval; megaspores gray when wet, white when dry, rugulate on basal side, other sides of megaspores tuberculate, 280 to 390 u in dia- meter; rnicrospores gray, elliptic, with small spines, 25 x 15g..
    Only known from Taiwan. Growing in shallow ponds, submersed most of the year.
    TAIPEI: Chonghu (Chihsingshan), Hsu & Chang 1715. De Vol 8005. *