披散问荆

Equisetum diffusum D. Don in Prodr. Fl. Nepal. 19. 1825: C. B. Clarke in Trans. Linn. Soc. II. Bot. 1: 594. 1880; Baker, Handb. Fern Allies 3. 1887; C. Chr. in Meddel. Fran Geoteb. Bot. Tr. 44: 108. 1924; Schaffner et L. C. Li in Bull. Fan Mem. Inst. Biol. Bot. 9: 125. 1939; Rothm. in Fedde, Repert. Sp. Nov. 54: 75. 1944; Tard. -Blotet C. Chr. in Fl. Indo-Chine 7 (2): 544, f. 64: 8-10. 1951: S. H. Fu, Ill. ImportantChinese Pl., Pterid. 14. 1957; Mehra et Bir in Res. Bull. Panjab Univ. 15 (1-2): 100. 1964; Tagawa in Hara, F. E. Himal. 2: 197. 1971: Ic. Corm. Sin. 1: 116. 1972; Fl. Tsinling. 2: 24. 1974; C. N. Page in Fern Gaz. 11 (1): 29, f. 7. 1974: K. Iwats. inOhashi, Fl. E. Himal. 3: 166. 1975; Y. L. Chang et al., Sporae Pterid. Sin. 51, pl. 5: 24-27. 1976; Fl. Xizang. 1: 31, f. 10: 1-2. 1983; P. S. Wang et X: Y. Wang inGuizhou Sci. 2: 50, 1983; Dixit, Census Ind. Pterid. 19. 1984; K. Iwats. et S. K. Wu et al. in J. Fac. Sci. Uni. Tokyo III. 14: 13. 1986; H. S. Kung, Fl. Sichuan. 6: 83, pl. 25: 1-2. 1988; Bir et al. in Ind. Fern. J. 6: 37. 1989; P. S. Wang, Pterid. Fanj ing Mt. Nat. Res. 26. 1992: Fl. Dulongjiang Reg. 3. 1993: C. M. Zhang in W. T. Wang, Keys Vasc. Pl. Wuling Mts. 9. 1995; L. B. Zhang et H. S. Kung in X. C. Zhang et K. H. Shing, Ching Mem. Vol. 84. 2000. ——E. diffusum D. Don var. paucidentatum C. N. Page in Fern Gaz. 11 (1) : 31, f. 3: a. 1974. ——E. mekon-gense C. N. Page, l. c. 36. f. 3: d. f: 9.

中小型植物。根茎横走，直立或斜升，黑棕色，节和根密生黄棕色长毛或光滑无毛。地上枝当年枯萎。枝一型。高10-30 (70)厘米，中部直径1-2毫米，节间长1.5-6.0厘米，绿色，但下部1-3节节间黑棕色，无光泽，分枝多。主枝有脊4-10条，脊的两侧隆起成棱伸达鞘齿下部，每棱各有一行小瘤伸达鞘齿，鞘筒狭长，下部灰绿色，上部黑棕色；鞘齿5-10枚，披针形，先端尾状，革质，黑棕色，有一深纵沟贯穿整个鞘背，宿存。侧枝纤细，较硬，圆柱状，有脊4-8条，脊的两侧有棱及小瘤，鞘齿4-6个，三角形，革质，灰绿色，宿存。孢子囊穗圆柱状，长1-9厘米，直径4-8毫米，顶端钝，成熟时柄伸长，柄长1-3厘米。

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