236 



THIRD GROUP. VASCULAR CRYPTOGAMS. 



into two, afterwards into four lobes ; these are succeeded by normal leaves with a 

 long stalk and a four-lobed lamina which is at first rolled up. Pilularia agrees with 

 Marsilia in all these points according to Hanstein, only all the leaves are long, 

 conical, filiform, and at first rolled up spirally forwards (Fig. 191). 



The lateral shoots of the.Salviniaceae and Marsiliaceae are on the sides of the 



FIG. 190. Marsilia Salvatrix. An- 

 terior portion of the stem with leaves, 

 half the nat. size ; k terminal bud, b b 

 leaves, ff the sporocarps springing from 

 the leaf-stalks at x. 



FiG. 191. Pilularia globulifera. A the nat. size. 

 B the extremity magnified, J terminal bud of the stem, 

 bb' leaves, TV roots,/" sporocarps, AT lateral bud. 



stem, as has been already stated and as is often the case in dorsiventral shoots. In 

 this case a leaf stands over a lateral bud, and the branching therefore is not axillary. 

 The origin of the lateral buds in Salvinia has not yet been ascertained, but the 

 analogy of Azolla scarcely leaves room for doubt that they proceed from superficial 

 cells of the stem lying below and somewhat in front of or behind the origins of the 

 leaves. Adventitious shoots from leaves, which are so common in the homosporous 

 Ferns, are not known in the heterosporous. 



The growth of the roots in the Marsiliaceae and their monopodial branching are 

 the same in all the more important points as in the Ferns. It has been already 

 stated that in the Salviniaceae Salvinia itself has no roots, but that Azolla produces 

 roots near the lateral shoots from the two rows of cells on the ventral face of the 



