LYCOPODIACE.E. 



[ 405 ] 



LYCOPODIACE.E. 



general terms. The bifurcating branched 

 stem, rooting at each fork by a slender 

 thread-like adventitious root, and the ordi- 

 narily small overlapping leaves, distinguish 

 most of the species of Lycopodium; but there 

 is considerable variation from this habit in 

 the Psilotete, especially in Isoetes, and the 

 nature of the fructification is the only mark 

 generally applicable. The Lycopodiacese 

 bear spores which are found in small dehis- 

 cent cases at the bases of the leaves (figs. 

 427, 430 and 431), on the upper face or im- 

 bedded in it, and these fertile leaves are 

 either scattered all along the stem, or col- 

 lected into spikes resembling, on a small 

 scale, 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 lo\nest scales 

 (oosporanges) producing only four spores 

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

 those contained in large number in the other 

 spore-cases (pollen-sporanges] (figs. 431 , 433) . 



Fig. 434. 



Selaginella cernua. Half nat. size. 



In both of these genera thesporanges have but 

 one cavity; in Tmesipteris the sporanges are 

 two-celled, and in Psilotum three-celled. In 

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

 seated on a tuberous stem, and most of them 

 fertile, the sporanges containing spores of 

 each kind are many-celled, and immersed 

 in the substance of the bases of the leaves. 



The anatomical structure of the stem of 

 the Lycopodieae is not very complex. There 

 is an outer thickish rind, composed of cellu- 

 lar tissue, and on cutting across a stem, the 

 ends of isolated fibro-vascular bundles are 

 sometimes seen traversing this ; these iso- 

 lated bundles are 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, connected with the central 

 cord of the stem. The structure of the 

 little-developed tuberous stem of Isoetes is 

 very different, and exhibits a remarkable 

 mode of growth, forming annual layers of 

 woody structure (see ISOETES). 



The leaves are of very simple structure, 



