SECOND GRAND DIVISION, 

 CRYPTOGAMIA, OR FLOWERLESS PLANTS. 



Plants chiejiy composed of cellular tissue^ without spiral vessels, des- 

 titute of true flowers^ and producing spores 

 instead of seeds. 



CliASS V. ACROGENS. 



Flowerless plants with a proper stem or axis, often with a vascu- 

 lar system composed chiefly of annular ducts, usually furnished with 

 leaves. Gtrowth by the extension of the apex, without" subsequent 

 increase in diameter. Spores with a proper integument, and con- 

 tained in a vessel analogous to an ovary, called theca or sporangium. 



Order CLXII. EQUISETACE^.— Horsetails. 



Plant leafless, simple or with verticillate branches. 



Slem striatesulcate, jointed, fi.stiilar between, and separable at, the joints. 



Sheaths dentate, crowning the sumnait of each internode. 



Inflorescence, (by analogy) a dense, cylindric, terminal spike or strobile. 



Scales of the strobile peltate, hexagonal, subverticillate. 



Thecce 4—7, attached to the under surface of the scales, with lateral dehiscence. 



Spores numerous, globose, surrounded by minute granules. Imanner. 



Elalers, bodies of unknown use, consisting of 4 elastic, clavate filaments involving the spores in a spiral 



An order consisting at present of a single genus, growing in wet grounds, on river banks, and borders 

 of woods, throughout most countries. The Equisetacese abound in the fossil remains of coal measures 

 with other Cryptog.imia, as Lycopodiaceee and Filices, indicating that these plants were once of gigantic 

 dimensions, and formed a large part of the original flora of our globe. Species about 10. 



Properties.— They abound in silex, and hence are used by cabinet-makers, comb-makers, &c., in polish- 

 ing their work. 



EaUISETUM. 



Lat equns, a horse, seta, hair; perhajis alluding to the general resemblance. 



Character the same as that of the order. 



1. E. HYEMALE. Scouring Rusk. 



. Sts. all .simple, erect, very rough, each bearing a terminal, ovoid spike ; 

 sheath cinerous white, black at the base and summit, short, with subulate, 

 awned and deciduous teeth. — Very noticeable in wet, shady grounds, and by 

 brooksides. Stems about 2f high, often 2 or more united at base from the same 

 root. Sheaths 2 — 3" long, 1 — 2^' apart, the white ring much broader than the 

 black, at length entire from the falling off of the teeth. The roughness of the 

 cuticle is owing to the silex in its compo.sition. June. 



2. E. ARVENSE. Mdd Horsetail. 



Fcrlil': sis. erect, simple, sterile with simple, quadrangular branches, de- 

 cumbent at base. — Low grounds, Free States and Brit. Am. Fertile stems first 

 appearing, 6 — 8' high, with 3 — 5 joints surmounted by large, inflated sheaths cut 

 into long, dark brown teeth. Spike oblong, J— 2' long. Sterile stems rather 

 taller than the fertile, remaining through the season, after these have decayed.. 

 At each joint is a whorl of simple, rough, ascending branches, Issuing froni the 

 base of the sheaths, their joints also sheathed. April. 



3. E. SYLVATicuM. Wood Horsetail. 



Sferik bmA fertile sis. with compound, rough, deflexed, angular branches.— 

 Grows in woods ,ajid low grounds, Free States and Brit. Am. Stems 9— IG' 



