648 FILICES. 



not decrescent.— Hook. Grev. Ic. t. 109.— L. tetragouum, Hook. Grev. : the transverse 

 furrow on the back of the leaf-base, by which Spring has distinguished from it L. myrsi- 

 nites, is not constant.— Leaves %"-V" long.— Hab. Dominica ; Trinidad {Spring) ; [Haiti 

 to Brazil !, Ecuador !, Peru]. 



3. PSILOTUM, Sw. 

 Sporangia 3-celled, loculicide : spores oo. — Leaves minute, distant, fertile ones bifid. 



22. P. triquetrum, Sw. Stem dicliotomous above : branches numerous, 3-quetrous ; 

 sterile leaves shortly linear.— Plum. Fil. t. 170. A. Schk. Crypt, t. 165.*. fig. Meet.— 

 Lycopodium nudum] L. — Hab. Jamaica !, Pd., on trees and decayed wood ; Dominica ., 

 S. Vincent!, Guild.; [all tropical countries to Louisiana!, Carolina!, Australia!, and 

 Southern China !]. 



23. P. complanatum, Sw. Stem several times forked : branches distant, fiat-com- 

 pressed, forming serratures at the oriain of the marginal, subulate leaves. — Schk. Crypt. I. 

 165. b. fig. sin.~ P. flaccidum, Walt— Hab. Jamaica (Sw.), on trees ; [Cuba!, Wr. 947 ; 

 Mexico !; Pacific islands ! ; East Indies !]. 



CLI. EQUISETACE^). 



Sporangia longitudinally dehiscent, inserted at the under side of peltate scales, the latter 

 racemose in a small cone: spores supported by 2 elastic fibres (the elateres). — Stem jointed; 

 joints sheathed by united scales, longitudinally furrowed, leafless : branches whorled. 



EQUISETUM, L. 



Single genus. 



§ 1. Stem persistent : mostly the branches only rough. — " Stomata 2-serial in the 

 furrows, suuk beneath the epidermis." 



1. E. giganteum, L. Stem stout, 20-30 (-42) -furrowed, rather smooth : sheaths 

 appressed, white, their teeth deciduous, partially combined ; branches numerous, ascending, 

 simple, fertile rough, 6-7 (-8) -furrowed, their sheaths somewhat spreading, with scarious, 

 whitish, persistent teeth..— Desc. Fl. 2. t. 112.— E. Humboldtianum, Fendl. PI. Venez. 

 1801 : a form "not less than 20' high " (Fendl.), but the stem of his specimen uot stouter 

 than in the Jamaica plant, viz. 6'" diam. ; in E. xylochaetum, MM. (E. Lechleri, Milde. !, 

 E. giganteum, Gay, Fl. Chil. 6. p. 471), the stem is often 1" thick and the sheath-teeth 

 black and persistent. — 4'-6' high or much higher ; each row of stomata usually double. 

 Hxb. Jamaica!, Pd., March, Wils., in lagoons and swamps, at the ferry, Morant Bay; 

 Trinidad!, Cr. ; [Haiti to Martinique; Mexico!; Venezuela!; Peru!; Minas Geraes. 

 (Gardn., 15' high) ; Chile]. 



§ 2. Stem decaying in the tointer to the rhizoma. — " Stomata scattered in the furrows, 



superficial." 



2. E. palustre, L. Stem deeply 8 (6-9) -furrowed, slightly roughish, sterile and fer- 

 tile green : sheaths appressed : teeth persistent, lanceolate-acumiuate, erect, blackish ; 

 branches simple, usually 5(4-6)-fnrrowed ; cone blunt. — The allied South American E. bo- 

 gotense, Kth. (Fendl. Venez. 2182), has 4-furrowed, nearly simple stems and loose sheaths. 

 — Hab. S. Vincent !, Guild., according to a single specimen, on the same sheet with North 

 American specimens, in Herb. Hook. ; [northern temperate zone], 



CLII. FILICES. 



Sporangia at the under side (rarely on both sides) of a leaf in sori. — Leaf circinate (ex- 

 cept in Ophioglosum) . 



