Equisetum giganteum

Kessler, Michael & Smith, Alan R., 2017, Prodromus of a fern flora for Bolivia. VII. Equisetaceae, Phytotaxa 327 (1), pp. 97-99 : 98

Equisetum giganteum L., Syst. Nat. (ed. 10) 2: 1318. 1759.

Equisetum bolivianum Gandoger, Bull. Soc. Bot. France 66: 304. 1920.

Range:— Greater Antilles; Honduras to Chile, Argentina, and Uruguay. In Bolivia, found in CH, CO, LP, SC, and TA.

Ecology:— Locally common to dominant; aquatic and terrestrial in wetlands, sloughs, on the banks of streams, in irrigation ditches, and along rivers, both in humid and in arid intermontane regions, also occasionally on open soil of landslides; to 3500 m.

Notes:— Equisetum myriochaetum Schltdl. & Cham. , from Mexico to Peru, may occur in Bolivia. It differs from E. giganteum by having the stomata (best seen in main stem) in one straight line on each side of the ridges (i.e., in 2 lines in each groove vs. 3–4 lines on each side of the ridges, i.e., to 8 lines in each groove in E. giganteum ) and ridges of the branches also with elongate saw-teeth (vs. only with flat-topped, often isodiametic tubercles). Equisetum × schaffneri Milde is the putative hybrid between E. giganteum and E. myriochaetum . It has characters intermediate between both species and may also occur in Bolivia. It produces only malformed, presumably non-viable spores but may outcompete its parents locally due to hybrid vigor.