CLASS III. ACOTYLE'DONES OR CEYPTOGAMS. 



DIVISION I. VASCULA'RES. 

 ORDER I. FIL ICES. 



Herbs, rarely shrubby or arborescent, with fibrous roots, or perennial 

 short or long and creeping rootstocks. Leaves (fronds) tufted or alter- 

 nate on the rootstock, simple pinnatifid or 1-4-pinnate, usually circinate 

 in vernation ; petiole (stipes) sometimes jointed at the base and rachis 

 grooved on the upper surface. Fructification of microscopic spores, con- 

 tained in usually minute capsules that are collected in masses (sori) on the 

 under surface or edge of the frond, or rarely on separate fronds or parts of 

 the frond, and are naked or covered with an involucre formed of or upon 

 the margin or back of the frond. Capsules membranous, sessile or stalked, 

 often mixed with jointed club-shaped hairs or imperfect capsules. Spores 

 usually obtusely 4-hedral. DISTRIB. Chiefly humid temp, and trop. 

 regions ; genera 75 ; species 2,500. AFFINITIES. "With Lycopodiacece. 

 In germination the spore bursts, and develops a flat cellular scale (prothal- 

 lus), on the under surface of which are formed cavities some containing 

 male and some female organs. The male cavities (antheridia) contain sperm - 

 cells (spermatozoids or antfarozoids), which enclose a spiral filament. The 

 female cavities (archegonia) contain a solitary free germ-cell. The anthero- 

 zoids find their way into the archegonia and fertilize the germ-cell, which 

 thereupon develops into a plant, the prothallus withering away. 

 TEIBE I. HYMENOPHYL'IiEJE. Frond very membranous, translucent, 

 reticulate. Involucre 2-valved, urceolate or 2-lipped. Capsules minute, 

 membranous, reticulate, sessile on a clavate or filiform receptacle, girt by 

 a complete horizontal or oblique ring. Vernation circinate. 



Involucre 2-valved 1. Hymenophyllum. 



Involucre urceolate 2. Trichomanes. 



TRIBE II. POLYPO'DIE^S. Frond more or less coriaceous, opaque. 

 . Involucre marginal or dorsal or 0. Capsules minute, membranous, reticu- 

 late, not raised on an elevated receptacle, stalked, partially girt by a 

 vertical ring, bursting transversely. Vernation circinate. 

 * Sori marginal ; involucre continuous with the reflexed or recurved 

 margin of the frond. 



Sori oblong, short 3. Adiantum. 



Sori linear, continuous. Fronds all similar 4. Pteris. 



Sori oblong, on special fronds 5. Cryptogramme. 



Sori linear, on special fronds 6. Lomaria. 



** Son dorsal, linear ; involucre linear. 



Involucre on a nerve, single 7. Asplenium. 



Involucre on a nerve, double 8. Scolopendriiun. 



*** Sori dorsal, globose ; involucre short. 

 Involucre lacerate, attached under the sorus 9. Woodsia. 



