THE VASCULAR CRYPTOGAMS 



sp, 



are colourless and destitute of leaves ; they grow straight 

 down to the soil and resemble roots, but have no root- 

 caps. On coming into contact with the ground they 

 branch, giving rise to subterranean rootlets, which have 

 root-caps as usual. 



If the plant which we examine is fruiting, we shall 

 find that some of the branches, 

 instead of creeping along near 

 the ground, grow straight 

 upwards ; it is these vertical 

 branches which form the 

 terminal spikes or cones. 

 The cones bear the repro- 

 ductive organs ; they differ 

 from the vegetative branches 

 in the fact that all their leaves 

 are of the same size (see Figs. 

 1 and 3). 



Other species of SdagineQa 

 differ very widely from that 

 just described. 



Some are minute creeping 

 plants of almost microscopic 

 dimensions, with unbranched 

 stems (S. simplex) ; others have 

 climbing stems, which ascend 

 tall trees, and may attain a 

 length of 60 feet (S. exaltata) ; 



while in others again the stem is stiff and erect, rising 

 vertically to a height of three feet from the ground (S. 

 grandis). 



A still more important variation is in the arrangement 

 of the leaves. The majority of species agree with S. 



FIG. 3. Selaginella helvetica, 

 showing procumbent stem 

 and two fertile spikes, r, 

 rhizophore ; sp, sporangia. 

 Slightly magnified. (After 

 Dodel-Port.) 



