LYCOPODIACEiE. 



[ 405 ] 



LYCOPODIACEiE. 



general terms. The bifurcating branched 

 tern, rooting at each fork by a slender 

 hread-hke adventitious root, and the ordi- 

 larily small overlapping leaves, distinguish 

 DOst of the species of Lycopodium; but there 

 s considerable variation from this habit in 

 he PsilotecB, especially in Isoetes, and the 

 lature of the fructification is the only mark 

 generally applicable. The Lycopodiaceae 

 tear spores which are found in small dehis- 

 ent cases at the bases of the leaves (tigs. 

 27, 430 and 431), on the upper face or im- 

 ledded in it, and these fertile leaves are 

 ither scattered all along the stem, or col- 

 3cted into spikes resembling, on a small 

 cale, elongated Pine-cones (figs. 429, 439). 



The plants of the genus Lycopodium proper 

 exhibit both these conditions, but in all 

 these cases the spores are small and nume- 

 rous. In Selaginella, to which belong the 

 elegant creeping Club-mosses, with flattened 

 leafy stems (often with a metallic lustre), 

 now so much grown in Wardian cases (fig. 

 434), the capsular leaves are in spikes, 

 which are found forming one arm of a bifur- 

 cation of the stem, while the other continues 

 the vegetative growth ; and in these spikes 

 we find the capsules on the lowest scales 

 [oosporanges] producing only four spores 

 (figs. 430, 432), of much larger size than 

 those contained in large number in the other 

 spore-cases (poZ/e/i-5/;oraw^es) (figs. 431, 433). 



Fig. 434. 



Selaginella cernua. Half nat. size. 



n both of these genera the sporanges have but 

 >ne cavity; in Tmesipteris the sporanges are 

 wo-celled, and in Fsilotmn three-celled. In 

 soetes (fig. 380), where all the leaves are 

 eated on a tuberous stem, and most of them 

 ertile, the sporanges containing spores of 

 sach kind are many-celled, and immersed 

 n the substance of the bases of the leaves. 



The anatomical structure of the stem of 

 he Lycopodieae is not very complex. There 

 s an outer thickish rind, composed of cellu- 

 ar tissue, and on cutting across a stem, the 

 ;nds of isolated fibro-vascular bundles are 

 sometimes seen traversing this ; these iso- 

 ated bundles arc merely a portion of those 



forming a kind of cord running up the centre 

 of the stem, whence they have been sent off 

 to supply the leaves. The fibro-vascular 

 bundles are composed of spiral-fibrous ducts 

 surrounded by elongated cellular tissue (see 

 Fibro-vascular bundles), which in large 

 woody stems become lignified by secondary 

 deposits. The roots have also a central 

 fibro-vascular cord, connectedwith the central 

 cord of the stem. The structure of the 

 little-developed tuberous stem of Isoetes is 

 very difi^erent, and exhibits a remarkable 

 mode of growth, forming annual layers of 

 woody structure (see Isoetes). 



The leaves are of very simple structure. 



