Diphasiastrum Holub, Preslia

Øllgaard, Benjamin, Kessler, Michael & Smith, Alan R., 2018, Prodromus of a fern flora for Bolivia. II. Lycopodiaceae, Phytotaxa 334 (3), pp. 255-294 : 259

Diphasiastrum Holub, Preslia 47(2): 104–105. 1975

= Lycopodium subg. Complanatostachys Herter, Bot. Jahrb. Syst. 43(Beibl. 98): 29. 1909.

= Lycopodium sect. Complanata Victorin, Contr. Lab. Bot. Univ. Montréal 3: 34–89. 1925.

= Diphasium Rothm. ser. Complanata Rothm., Feddes Repert. Spec. Nov. Regni Veg. 54: 64. 1944.

The sporophytes of this genus have subterranean, or creeping to subscandent main stems; dorsiventral, anisophyllous branchlets with decussate, trimorphic leaves, one dorsal and one ventral rank of narrow leaves and two lateral ranks of broad laterally compressed leaves; herbaceous branchlet leaves throughout; pedunculate strobili; subpeltate sporophylls; sporangial epidermal cells with evenly sinuate side walls; reticulate spores on all faces; carrot-shaped gametophytes; and x = 23. This description applies only to Bolivian plants; some species in North America and East Asia have radial, isophyllous branchlets.

Diphasiastrum occurs in north-temperate, arctic, and alpine regions, montane areas in the tropics (absent from Australia), and comprises approximately 20 species. The genus (as sect. Complanata) was monographed by Wilce (1965). Holub (1975) extensively discussed the relationships to other groups. Only one species is known in Bolivia.