riLiCES. (ferns.) 585 



SERIES II. 



CRYPTOGAMOUS or FLOWERLESS PLANTS. 



Vegetables destitute of proper flowers, and producing, 

 in the place of seeds, minute homogeneous bodies (spores) 

 containing no embryo. 



Class III. ACROGENS. 



Plants with a distinct stem, growing from the apex only, 

 containing woody fibre and vessels. 



Order 161. EQUISETACE^E. (Horsetail Family.) 

 Comprises only the genus 



1. EQUISETITM, L. Scouring Rush. 



Fructification terminal, spikeJ or cone-like. Spore-cases {sporangia) 6-7, 

 borne on the lower surface of the peltate scales, I-celled, opening on the inner 

 side. Spores loose, furnished at the base with 4 club-shaped elastic filaments 

 (elaters). — Stems leafless, grooved, hollow and jointed, bearing at the closed 

 joints a toothed sheath. 



I. E. Isevigatum, Braun. Stems perennial, mostly simple, the obtuse 

 ridges smooth, or roughened with minute tubercles ; sheaths appressed, with 

 numerous bristle-like caducous black teeth. — Stiff clay soil, North Carolina, 

 and northward. — Stem l^°-i° high. 



Order 162. FILICES. (Ferns.*) 



Leafy plants, mostly with perennial rootstocks (caudex), which in this 

 climate are creeping and slender, or stouter and sometimes ascending, 

 but in the tropics oflen grow many feet high, with a diameter of several 

 inches, giving the plants an arborescent appearance (Tree-ferns'). Leaves 

 (fronds) circinately rolled up in vernation (except the last Suborder), 

 and raised on a stalk or petiole (stipe). Spore-cases (sporangia) one- 



* By Daniel C. Eaton. 



