THE VASCULAR CRYPTOGAMS 



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 Selayinella 

 differ very widely from that 

 just described. 



Some are minute creeping 

 plants of almost microscopic 

 dimensions, with unbranched 

 steins (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. 



FJG. 3. SelayiiicZla ficlvctica, 

 showing procumbent stem 

 and two fertile spikes, r, 

 rhizophore ; sp, sporangia. 

 Slightly magnified. (After 

 Dodel-Port. ) 



