654 EQCISETACE^. (hOKSETAIL FAMILY.) 



§ 1. Annual-stemmed, not surviving the winter. (Stomata sc.itti-.red.) 



* Fruiting in spring from sojl and rather succulent /lule or brownish fertile stems, the 



sterile stems or branches appearing later, herbaceous and v<rij dijfercnt. 

 ■*- Fertile stems remaining simple, soon perishing ; the sterile pioducing copious branches. 



1. E. Telmatdia, Ehrh. (Great Horsetail.) Stems stout (as thick 

 as the (iiiyer) ; the she-aths of the fertile ones (I'-l^' lon>^) enlarging upwards, 

 (k'ii)ly 20 - 30-tootiicd ; sterile stem white, 20 - 30-furrowed ; its branches simple, 

 rou<i:h, usually 4-anglcd and again grooved on the angles. (E. ehiirneum, Roih., 

 Schreber, and Ed. 2. E. fluvia'tile, Smith.) — Shore of the upper Great Lakes, 

 and northwestward: rare. April, May. — Fertile stems 10'- 15', the sterile 

 2° -5° high. (Eu.) 



2. E. arvense, L (Co.-mmo\ II.) Fertile stems (4'- 10' high) with 

 loo.sc and usually distant about 8-12toothed sheaths; the sterile slender (at 

 length l°-2° high), 10- l4-furrowcd, producing long and simple or sparingly 

 branched 4-angular branches ; their teeth 4, herbaceous, lanceolate. — Moist, 

 especially gravelly soil : very common. March - May. — Uootstocks occasionally 

 bearing copious little tubers like small peas (Illinois, S. A. Collier). — The var. 

 SEROTiNUM, Meyer, an accidental state, in which the sterile plant produces a 

 spike of fruit fi-om its summit, is found in New Jersey by C. F. Austin. 



•1- •♦- Fertile stems when older producing herbaceous 3-sided branches, and lasting 

 through the summer, except the naked top which perishes after fruclijication. 



3. E. pratense, Ehrh. Sterile and finally also the fertile stems producing 

 simple straight branches; sheaths of the stem with ovate-lanceolate short teeth, 

 those of the branches 3-toothed : stems more slender and the branches shorter 

 than in the last. (E. urabro.sum, Willd. E. Drummdndii, //ooA.) — Michigan 

 [Cuoleij, <jr.), Wisconsin, and northward. April, May. (Eu.) 



4. E. sylv^ticum, L. Sterile and fertile stems (about 12-furrowed) pro- 

 ducing com/JOKHC? racc/Herf /jrancAcs; sheaths loose, with 8-14 rather blunt teeth, 

 those of the branches bearing 4 or .=>, of the branchlcts 3, lance-pointed divergent 

 teeth. — Wet shady places : common northward. M.ay. (Eu.) 



* * Fruiting in summer ; the stems all of one kind, or the fertile contemporaneous with 



and like the sterile, equally herbaceous, producing mostig simple branches, or some- 

 times nenrlg naked. 



5. E. palustl'e, L. Stems (lO'-lS'high) slender, i'er//£/ee/)///.'J-9-<7raoiW, 

 the grooves separated by nari'ow wing-like ridges, roughish, the lance-awl-shaped 

 teeth whitish-margined ; branches rather few in a whorl. — Wet places, Niagara 

 River (C IF. C//"ton), Wisconsin (C. F. yl«s//;0, and northward. June. (Eu.) 



6. E. Iim6sum, L. Stems (2° -3° high) sliglitlg many -furrowed, smooth, 

 usually producing u])right branches after fructification; sheaths appressed, with 

 10-22 (commonly about 18) dark-brown and acute rigid short teeth. (E. uli- 

 ginbsum, Mnhl.) — In shallow water : rather common. — Air-cavities none under 

 the grooves, but small ones under the ridges. June, July. (Eu.) 



(E. littou.Vle, Kiihlewein, a species of N. Europe which stands between 

 No. 5 and No. 6, is said by Milde to grow in Canada, on the authority of a 

 •pecimen in l»erb. Hook., and may be looked for northward.) 



