ORDER 159. 



813 



tary, quadrangular. A very small species, creeping on rocks, moss-like. Stem a 

 few inches in length, with numerous branches, which are \ 1' long, clothed with 

 grayish-green leaves. Spike ' long, 4-rowed, seeming a mere continuation of tbo 

 branch. Jl. (S. rupestre L.) 



2 S. selaginoides Gray. St. filiform, creeping ; branches nearly erect, the flow- 

 ering ones simple ; Ivs. scattered, lanceolate, a little spreading, ciliate-dcnticulate ; 

 spike solitary, leafy. In moist woods, N. States and Can. Spikes yellowish- 

 green, about f" long, the bracts foliaceous and twice larger than the true leave?, 

 which are about a line in length. Branches 36' high, the sterile ones muclv 

 divided. Jl. (L. selag. L. S. spinosa Beauv.) 



3 S. apus Spring. St. branching, prostrate and rooting near the base ; Ivs. or- 

 bicular-ovate, acute, membranaceous, alternate, amplexicaul, in 2 rows, with 

 minute, acuminate, superficial ones in a third row on the upper side ; spikes sub- 

 solitary. A small, creeping, moss-like species, in wet, rocky shades. Can. to Ga., 

 not common. Stem 2 5' inches long, filiform. Leaves less than a line in length. 

 Spikes leafy, scarcely distinguishable from the branches. July, Aug. (L. apo- 

 dum L.) 



4 S. ornitliopodioides Spr. BIRD-CLAW Moss, Lvs. semicordate, ovate, 

 obtusish, entire, in 4 rows, the lateral spreading, distant below, crowded above, 

 the superficial much smaller, appressed ; spikes lateral, axillary, sessile ; stems and 

 branches prostrate. Greenhouse and gardens. A pretty moss-like creeper, with 

 light green foliage, f Eur. 



3. .PSILO'TUM, R. Br. (Gr. ^iMg, naked.) Sporangia sessile, 3- 

 celled, imperfectly 3-valved by terminal chinks, filled with farinaceous 

 spores. Stem fork-branched, with alternate, minute leaves, as if leafless. 

 (Bernhardia, Willd.) 



P. triquetrum Swtz. Stem erect, many times forked, and branches three-angled, 

 8 to 10' high; Ivs. remote, subulate, less than 1'' long, and the 3-lobed fruit ses- 

 sile along the branches. Rocky cliffs, on the sea-coast of E. Fla. (Michx. in 

 herb. Bachman.) 



ORDER CLIX. EQUISETACE^E. HORSETAILS. 



Plants leafless, simple stems, or with whorled branches. Stems striato-sulcate, 

 jointed, fistular between, and separable at, the joints. Sheaths dentate, crowning 

 each internode. Fructification a dense, oblong-cylindric, terminal and cone-liko 

 spike, composed of G-sided, peltate-scales arranged spirally, bearing beneath 4 to 7 

 spore-cases which open laterally. Spores globular, each with 4 elaters attached, 

 involving them spirally, or open when discharged. (See Figures.) 



nsisting at present of a single genu*, growing i 



ds, throughout most countries. The Equiseta( 



coal measures with other Cryptogamia, as Lycopodiaceas and Filices, indicating that th 



An Order 

 borders 



et grounds, on rivor banks, r;nd 

 taceue abound in the fossil remains of 



plants were once of gigantic dimensions, 

 and formed a large part of the original flora 

 of on r globe. Species about 10. 



Properties. They abound in silex, and 

 hence are used by cabinet-makers, comb- 

 makers, &c., in polishing their work. 



EQUISETUM, L. SCOURING 

 RUSH. (Lat. equus, a, horse, seta, 

 hair.) Character the same as that 

 of the order. The sheaths may 

 be regarded as a whorl of united 

 leaves. The ridges of the stem 

 are air-tubes, and the grooves 

 alone are pierced with the sto- 



with T sporan-es beneath (or one com 

 range), magnified. 738, A spore with 

 highly magnified. 



pound spo- 

 its elators, 



