CLASSIFICATION. 



produced in large numbers on the back or margin of leaves 

 (fertile fronds, sporophylls) and are usually collected 

 together iu small groups (sori). Fertile fronds either 

 altogether resemble the barren ones or are specially modified. 

 The prothallia when fully developed produce archegonia 

 and antheridia. 



Order I. Filicales. (p. 54) Order II. Marattiales. (p. 56). 



Division— PHANEROGA9II4. 



This division includes practically all the trees and shrubs 

 of the present time. Spores of two kinds (hetetosporous). 

 Male spores (microspore, pollen-grain) borne on specially 

 modified sporophylls (stamens) in sporangia (poll en- sacs). 

 The female npore (macrospore, embryo-sac) never quits the 

 macros porangium (nucellus), which becomes invested by one 

 or more envelopes (integuments) derived from the parent 

 plant, and with them constitutes the ovule. The prothallium 

 (if formed i develops entirely within the mncrospore, and the 

 fertilized bosphere forms an embryo inside the ovule, which 

 after further changes consequent on fertilization becomes 

 the seed. The microspore on germination gives rise to the 

 pollen tube. Sub-divisions. — Gymnospermre, Angiospermae. 



Sub-division I— Gynmospermae. 



Trees or shrnbs (including such well-known trees as 

 the pines, yew, etc.), very rarely scandent. Fls. 1 -sexual 

 often cone-like. Female sporophyll (carpel) bearing the 

 ovules on its margin or surface, never infolded or cohering by 

 ihe edges with other carpels to form a closed ovary (N.B. the 

 ovules may be concealed from view after fertilization by the 

 overlapping of the carpels). Pollen grains borne by the wind 

 direct to the exposed micropyle of the ovule. Prothallium. 



48 



