FILICINEAE. HOMOSPOROUS FILICINEAE. 



211 







rupestriS) and many of the Polypodieae answer to the two rows of segments of the 

 apical cell of the stem ; but in the case of a more complicated spiral phyllotaxis with 

 an apical cell which is a three-sided pyramid, as in Aspidium Filix-mas, the processes 

 may be similar to those which take place in Mosses with many rows of leaves and a 

 three-sided apical cell, as for instance in Polytrichum 1 . 



The branching and the position of the lateral buds are liable to considerable 

 variation in the different species. The lateral buds are either on the dorsal side of 



FIG. 158. Aspidium Filix-mas. A longitudinal section through the extremity of a stem ; -v the apical region of 

 the stem st, bb the leaf-stalks, b' a young still folded leaf, the others being concealed by long paleae, g vascular bundles. 

 B a leaf-stalk of the same plant broken off and bearing at k a bud with several leaves ; TV a root of the bud k. C a similar 

 leaf-stalk cut through lengthwise, bearing a root at TV and a bud at h. D extremity of a stem from which the leaves 

 have been cut off at the base of the stalks, the youngest leaves only of the terminal bud being retained in order to show 

 the arrangement of the leaves ; the spaces between the leaf-stalks are filled with numerous roots TV TV', all of which have 

 sprung from the stalks. E extremity of a stem from which the rind has been removed to show the net-work of vascular 

 bundles . F a mesh of the net-work slightly magnified showing the basal portions of the bundles which pass out into 

 the leaves. 



the bases of the leaves, as in Aspidium Filix-mas (Fig. 158), where they appear in 

 rudimentary form at a very early period, or they are placed laterally with respect to 

 them on the stem, and either above or below the insertion of the leaf, seldom in the 

 axil of the leaf, as in higher plants. But on radial stems it is only a very small 

 number of leaves that have lateral buds associated with them (Mettenius asserts that 



1 Hofmeister, Allg. Morphol. p. 509, and in Bot. Ztg. 1870, p. 441. 



P 2 



