248 



THIRD GROUP. — VASCULAR CRYPTOGAMS. 



the outer sterile branch and the sporangiferous branch of the leaf are usually un- 

 branched (Fig. 202 A); in the Brazilian species, Ophioglossimi palmahnn, the lamina 

 is dichotomously lobed, and several sporangiferous lobes arise from either side of the 

 margin of the lamina where it passes into the stalk. In Botrychiuin both branches are 

 again branched in parallel planes. (Fig. 202 B). The earlier idea of a cohesion of the 

 two stalks of a fertile and a sterile leaf is at once disproved by the history of development 



Fig. 204. Longitudinal sec- 

 tion of the upper part of the 

 fertile lamina of Ophioglossitm 

 ■vulgatum ; .r its free apex, sp 

 the sporangial cavities, r the 

 spot where they open trans- 

 versely, g the vascular bundles. 

 Magn. about lo times. 



Fig. 203. Longitudinal section through the lower portion of a developed plant of Botrychium Lunaria \ st stem, 

 e, g' vascular bundles, iu a young root, s apex of the stem, b. b' b" b"' the four leaves already formed, b"' the one 

 unfolded in the present year ; ^^ shows the first indication of the branching of the leaf, in *" this is already considerably 

 advanced ; m is the median line of the sterile lamina, which has its lobes already formed to the right and left but not 

 visible in this figure,/ is the fertile lamina with the young branches, on wliich the sporangia will be formed. Magn. 

 about 10 times. 



(Fig. 203), which shows, as Hofmeister pointed out, that the sporangiferous branch 

 proceeds from the inner side of the leaf. The fertile branch of the leaf either separates 

 when fully developed from the sterile green branch at the base of the lamina, or it springs 

 from the middle of the lamina, as in O. petiduhwi, or the two branches of the leaf 

 appear to be separated as deep down as the insertion, as in O. Bergtaniim, or finally 



