648 FILICES. 



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

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

 niies, is not constant.— Leaves 2"'-l"' long. — Hab. Dominica ; Trinidad {Sprmg) ; [Haiti 

 to Brazil !, Ecuador !, Peru]. 



3. PSILOTUM, Sw. 



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



23. P. triquetrum, Sw. Stem dichotomous above : branches numerous, 3-^efrous ; 



', sterile leaves shortly linear. — Plum. Ml. t. 170. A. Schk. Crypt, t. 165. b. Jig. med. — 



■ 'Lycopodium nudum, L. — Hab. Jamaica I, Fd., on trees and decayed wood ; Dominica !, 



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



Southern China !]. 



23. P. complanatum, Su>. Stem several times forked : branches distant, jlat-com- 

 pressed, forming serratures at the origin of the marginal, subulate leaves. — Schk. Crypt, t. 

 'l^h.b.fg. sin. — P. flaccidum. Wall. — Hab. Jamaica (Sw.), on trees ; [Cuba!, Wr.9i1; 

 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, Z. 



Single genus. 



§ 1. Stem persistent : mostly the branches only rough. — "Stomata 3-serial in the 

 furrows, sunk beneath the epidermis." 



1. E. i^iganteum, L. Stem stout, %0-S0(-42) furrowed, rather smooth : sheatJis 

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

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

 whitish, persistent teti\.^-I)esc. PI. 2. t. 112. — E. Humboldtianum, Fendl. PI. Venez. 

 1801 : a form "not less than 30' high" {Fendl), hut the stem of his specimen not stouter 

 than in the Jamaica plant, viz. 6'" diam. ; in E. xylochsetum,'Me<<. (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. — 

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

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

 {Gardn., 15' high) j Chile]. 



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



superficial." 



' 2. E. palustre, £. Stem rfeepi^ 8(6-9) /an-owe^?, slightly ronghish, sterile and fer- 

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

 branches simple, usually 5 (4-6)-furrowed ; cone blunt. — The allied South American ^. 4o- 

 gotense, Kth. (Fendl. Venez. 2182), has 4-furr,owed, 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. MLICES. 



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

 cept in Ophioglosum). 



