342 
THE FERNS OF SOUTH AFRICA 
219. PSILOTUM TRIQUETRUM Swartz. 
Plate 1 8 1. Fig. 2. Nat. size. 
Rhizome wiry, creeping. Stems three-angled, six to 
eighteen inches long, almost leafless, very much twisted 
throughout, dichotomously forked repeatedly, the ultimate 
branches one to four inches long. The leaves are few and 
rigid, ovate, pointed, set on the angles of the stem, and 
bearing the sporangiophores in their axils. 
P. triquetrum Swartz. Pappe and Rawson, 50; Baker, Fern Allies, 30 ; 
Sim, Ferns of S. Afr ., 1st ed., 247. 
Lycopodium nudum. Linn. Sp. 1564. 
Bernhardia capensis. C. Muller. 
Tropics generally, and a little beyond them; epiphytal on 
trees. 
Natal. — (Gueinzius); on the coast, rare; bush swamp at head of Bay 
of Natal (Buchanan); Murchison Flats (Wood, 2429); Edendale 
(T. R. Sim). 
Rhodesia. — In rain forest at Victoria Falls (Eyles, 1 1 5 ; Engler). 
COHORT IV. EQUISETALES. 
ORDER IX. EQUISETACEAE. 
Genus 61. Equisetum Linn. 
The only genus in the order. Plants of very distinct 
habit, having no leaves, but with hollow-ribbed stems, coated 
with silica, rising from long solid underground rhizomes. The 
stems are jointed at regular distances, and at each joint the 
lower node is surmounted by a whorl of membranaceous teeth, 
surrounding the base of the next node (fig. e). These teeth 
are mostly connate, except at the tips, and are equal in number 
to the ribs on the stem. Each rib is hollow in addition to the 
large central tube of the stem. In some species the stem is 
simple, in others similar, but smaller branches proceed in 
regular whorls, or, as in our species irregularly, from inside 
the sheath at the joints. The fertile cone is terminal on the 
stem or branches, and composed of numerous, peltate, many- 
sided, roundish receptacles (figs, b, c), bearing on the under 
