Order 159.— EQTJISETACE^E. 



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 the 

 branch. Jl. (S. rupestro L.) 



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

 ering ones simple ; lvs. scattered, lanceolate, a little spreading, ciUate-dcnticulair. ; 

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

 green, about f ' ' long, the bracts foliaceous and twice larger than the true leaves, 

 which are about a line in length. Branches 3 — 6' high, tho sterile ones much 

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



3 S. apus Spring. St. branching, prostrate and rooting near the base ; lvs. 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. ornithopo&ioides Spr. Bird-claw Moss. Lvs. semicordato, 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. PSILQTUM, R. Br. (Gr. ^tXoq, naked.) Sporangia sessile, 3- 

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

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

 (Bcrnhardia, Willd.) 



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

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

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

 herb. Baehmaru) 



Order CLIX. EQTTISETACE^E. Horsetails. 



Plants leafless, simplo stems, or with whorled branches. Stems striatc-sulcate, 

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

 each intcrnode. Fructification a dense, oblong-cylindric, terminal and conc-lika 

 spike, composed of G-sided, peltate-scales arranged spirally, bearing beneath 4 to 1 

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

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



An Order consisting at present of a single genua, growing in wet grounds, on river banks, and 

 borders of woods, throughout most countries; The Equisetacea? abound in the fossil remains of 

 «oal measures with other Oyptogamia, as Lycopodiacea; and Filices, indicating that these 

 plants were onee of gigantic dimensions, 

 and formed a large part of the original flora 

 of our globe. Specie* about 10. 



Properties. — They abound in silex, and 

 lience are used by cabinet-makers, comb- 

 makers, ifcc., in polishing their work. 



EQUISE^TUM, L. Scouring 

 Rush. (Lat. cquus, a horse, seta, 

 hair.) Character tbc 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 7S4, Equisetum arvenso. 735, E. sylvaticum. 786, 



^^tion of the Bpike, enlarge 

 alone are pierced AVlth the Stp- with 7 sporanges bennath ( 



. range>, magnified, 



maia. highly magnified. 



707, A peltato scalo 



one compound spo- 



73S, A fporo with its elators. 



