GENERAL KEY TO THE FAMILIES 

 I. Phylum PTERIDOPHYTA Shida-Shokubutsu Vascular Cryptogams 



Plants without true flowers and seeds, reproducing from spores borne in a sporangium; archegonia and antheridia pro- 

 duced on tlie same or different prothallia. About 26 families with more than 10,000 species, especially abundant in the 



Tropics. The sequence of the genera of true ferns follows the classification of Copeland, "Genera Filicum," 1947, with few 

 exceptions. 



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lA. Terrestrial or aquatic, never free-floating, always sedentary. 

 2A. Leaves snnall, entire, very numerous and imbricate, or quill-like and crowded on a short cormlike stem, or verticillate and 

 connate, forming a sheath around the stem. 

 3A. Stems conspicuously jointed, sheathed at the nodes; sporangia borne on the inner surface of peltate scales. 



Fam. 2. Equisetaceae, 21 

 3B. Stems not conspicuously jointed; sporangia in the axils of leaves or bracts, sometimes in terminal conelike spikes. 

 4A. Terrestrial plants with elongate usually leafy or scaly stems (practically naked in Psilotum). 



5A. Sporangium 3-locular; leaves scalelike Fam. 1. Psilotaceae, 2 1 



5B. Sporangium 1 -jocular; leaves densely imbricate. 



6A. Leaves without a ligule; spores all alike Fam. 3. Lycopodiaccae, 22 



6B. Leaves ligulate; spores of 2 kinds Fam. 4. Sclaginellaceae, 26 



4B. Mostly aquatic plants with short thick cormlike stems; leaves densely tufted and forming a rosette; spores of 2 kinds. 



Fam. 5. Isoetaceae, 28 

 2B. Leaves relatively large, flat, mostly toothed or variously compound. 

 7A. Fronds not 4-foliolate; sporangia not enclosed in basal sporocarps. 



8A. Vernation of fronds straight; plants fleshy, lacking sclerenchyma; .sporangia with massive walls, with stomata, lacking 



an annulus Fam. 6. Ophioglossaceae, 28 



8B. Vernation of fronds circinnate. 



9A. Huge ferns with stout fleshy globose rhizomes; fronds bipinnate; stipe with an enlarged fleshy joint attached by a 

 stipulelike outgrowth at base, each pinna and the pinnules similarly jointed; sporangia derived from plural cells, 



with a wall more than 1 cell thick Fam. 7. Maratnaceae, 31 



9B. Delicate to large ferns, rarely with a woody treelike stem; fronds variously cut, sometimes undivided, but the stipe with- 

 out a distinct fleshy enlargement or joint at base; sporangia derived from a single epidermal cell, with a wall 1 cell 

 thick. 

 lOA. Annulus rudimentary. 



11 A. Terrestrial perennials Fam. 8. Osmundaceae, 31 



IIB. Aquatic annuals Fam. 13. Parkeriaceae, 47 



lOB. Annulus well developed. 

 12A. Annulus transverse. 



13A. Annulus apical Fam. 9. Schizaeaceae, 32 



13B. Annulus median Fam. 10. Gleicheniaceae, 32 



12B. Annulus oblique or longitudinal. 



14A. Blades very thin, mosdy 1 cell thick, without specialized epidermis or stomata. 



Fam. 11. Hymenophyllaceae, 33 

 14B. Blades herbaceous, more than 1 cell thick, with epidermis and stomata. 



15A. Plant neither hairy nor scaly Fam. 15. Plagiogyriaceae, 48 



15B. Plant hairy or scaly, or both hairy and scaly. 



16A. Annulus complete, oblique; tree ferns Fam. 16. Cyatheaceac, 49 



16B. Annulus interrupted, longitudinal; herbaceous ferns, not or .scarcely arborescent. 



17A. Margins of the blades reflexed and usually covering the sori, a true indusium lacking, or, if present, the 



fertile segments not contracted and beadlike or podlike Fam. 12. Pteridaceae, 36 



17B. Margins of the blades not covering the sori (except in Onoclea and Matteticcia, with dimorphic fronds, 

 the fertile segments provided with a true indusium, contracted and podlike or beadlikc). 

 18A. Sori typically indusiate. 



19A. Fronds with elongate sori parallel to the costa or costules Fam. 18. Blcchnaceae, 89 



19B. Fronds without elongate sori, or, if present, these oblique to the costa. 



20A. Stipe or pinnae jointed at base Fam. 1 4. Davalliaceae, 47 



20B. Stipe or pinnae not jointed at base. 

 21A. Rhizomes scaly. 



22A. Rhizome scales clathrate, i.e., mostly broad and with dark thickened lateral walls and 



colorless thin outer walls Fam. 19. Aspleniaceae, 91 



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