96 



VASCULAR CRYPTOGAMS 



' vascular ' bundles of the stem are collateral ; the primitive elements of 

 the xylem are usually scalariform tracheides. 



The pophyte generation has been observed in only a few species. In 



Fig. j^.—Ophioglossum vulgatunt L. A^ p^ant (natural size) ; B, portion of 

 sporophyll (magnified). 



Ophioglossum (pedunculosum, Desv.) it has at first the form of a small 

 round parenchymatous tuber, entirely buried in the soil and destitute 

 of chlorophyll, from which is subsequently developed a cylindrical 

 vermiform shoot, which grows erect by means of a single apical cell, 



