478 THE FAMILIES, GENERA AND SPECIES OF PTERIDOPHYTA. 



A'ejLi'etative serial stems divided into a number of internodes 

 ])y the whorls of leaves; internodes hollow; nodes solid; stem 

 easily separated into segments just above the nodes. Each 

 internode has a large number of ridges and furrows, and bears 

 at its apex a whorl of leaves whose numbers and position cor- 

 respond to the ridges of the internodes. Whorls and ridges 

 placed alternately, one above the other. Stems stiff, due to 

 the presence of a large amount of silica in the cell-walls of the 

 epidermis and to the sclerenchymatous cells of the ridges. 

 Vegetative leaves simple, undivided, i-nerved, united 

 into toothed sheaths surrounding the base of the internode. 

 The branches break through the iDase of the leaf-sheaths and 

 generally alternate with the teeth. 



Only genus i.. Equisetum. 



I. Equisetum. Linn. 



The spike is very like the male flower of a Conifer, consisting 

 of an axis with short internodes. bearing" a densely packed mass 

 of sporophylls. Sporangia borne on the under side ( i.e. to- 

 wards the stem) of the sporophyll. — Perennial herbs with 

 sympodial rhizomes, which send up aerial shoots each year. 

 These mav be of one or two kinds ; in some species the ordinary 

 |::;reen shoot bears the reproductive spike at the end. while in 

 others there is a special reproductive shoot, usually appearing 

 early in the year, and often without chlorophyll the ordinary 

 shoots performing assimilating work only. Leaves closely 

 pressed against the stem; of little or no use in assimilation. 

 Surface of stem grooved ; ridges occupied by mechanical tissue 

 whilst the green tissue and stomata are at the base of the fur- 

 rows. This is a marked xerophytic structure and is repeated 

 A'erv closelv in Casuarina (the Beefwood trees). Only one 

 species. 



I. E. ramosissimum, Desf. Horse-tail; Dronk-gras. — 

 Marshy ground, usuallv near streams. Not common. Pretoria. 

 Pa.. Skinners Spruit. 'Burtt-Davy 2,490; P. P. Rust, Wg.. 

 Lccndcrtc 753; Barberton. Bn.. Thorncroft 89; Potchefstroom. 

 Dale, in T.l3.A. herb. 169; Wemmers Hoek, Lg.. Burtt-Davy \ 

 Duivel's Kloof. Ze.. T.D.A. herb. 4.950; Pinedene, Pa., Burtt- 

 Daz'v 2.329; Onderstepoort. Pa., T.D.A. herb. 4.150; near 

 Haenertsburg. Ze., T.D.A. h. 162; near Molepos location. 

 Zw.. T.D.A. h. 2.972; Pietersburg, Zw., T.D.A. h. 2,965; near 

 Ermelo. T.D..A.. h. ; near Shiluvane, Ze.. Jiiiiod 1,821. 



Class III.— LYCOPODI ALES (Ciub-mosses). 



Homosporotis or heterosporous ; in the latter case the female 

 prothallus remains enclosed in the spore till fertilization. 

 Sporangia borne singly on upper side of leaf-bases, or in their 

 axils, or on a sporangiophore and arranged in cones placed 

 terminallv on branches, thus limiting their growth. Sporangia 

 arising from groups of epidermal cells. — Perennial herbs; 

 roots generally branching dichotomously. Stem simple or 

 branched. Leaves many, small, entire, scattered or opposite, 

 and in proportion to the stem very small, scale-like and trian- 

 gular, tapering from a broad base to a point, green. 



