32 American Midland Naturalist Monograph No. 2 



KEYS TO THE GENERA AND SPECIES 

 Division I. Pteridophyta. Ferns and Fern-allies 



1. Lycopodiaceae Michx. — Clubmoss Family 



1. Lycopodium L. — Clubmoss 



1. Sporangia borne in the axils of foliar leaves, not in distinct terminal cones. 



2. Leaves linear-oblanceolate, glossy, widest above the middle, erose-denticu- 



late toward the apex; cool moist woods, rare; Cook Co., Vasey; Coles 



Co., E. L. Stover L. hicidnliim Michx. 



2. Leaves lanceol.-j.te-Iinear, widest at the base, nearly or quite entire; cool 



woods, rare; Lake, La Salle, and Ogle counties 



L. porophilum Lloyd & Underw. 



1. Sporangia borne in terminal cones; sporophylls similar to the foliar leaves; 

 Evanston, Sept. 20, 1890, L. N. Johnson L. inundatum L. 



2. Selaginellaceae Underw. 



1. Selaginella Beauv. — Selaginella 



1. Leaves numerous, uniformly imbricated, many-ranked, subulate, short-awned; 

 dry sandstone rocks, local; n. 111., extending southward to Henderson and 

 La Salle counties. Rock Selaginella S. rupestris (L.) Spring 



1. Leaves of two kinds, 4-ranked, spreading in two planes, ovate, acute or 

 cuspidate; moist soil, local. [S. apiis (L.) Spring}*.. .>S. apoda (L.) Fern. 



3. Isoetaceae Underw. — Quillwort Family 



1. IsoETES L. — Quillwort 



1. Leaf-bases blackish; megaspores 280-440 /i in diameter, nearly smooth, or 

 with low tubercles; microspores finely spinulose, ashy-gray; wet meadows 

 or shallow ponds, chiefly in the western part of the state, rare, or perhaps 

 now extinct in 111 I. melanopoda Gay & Dur. 



1. Leaf-bases not blackish; megaspores 400-600 /i in diameter, honeycomb- 

 reticulate; microspores smooth or nearly so; ponds, rare. St. Clair Co 



/. engelmauni A. Br. 



4. Equisetaceae Michx. — Horsetail Fainily 



1. Equisetum L. 



L Stems perennial, evergreen, all alike, stiff and harsh, usually simple; stomata 

 in regular rows in the grooves; cones usually apiculate. 

 2. Stems tall, 16-50-anglcd, hollow; teeth of the sheaths deciduous. 



* Synonyms appear in brackets. 



