Equisetaceae. Ophioglossem. 
429 
■ 
2. Stem (very thick) ivory-white. Sheaths with 20—30 teeth: 
E. Telemateia. 
— Stem green. Sheaths with 3—20 teeth . . 3 
3. Branches very fine, ramified: E. sylvaticum. 
— Branches (when present) gen. simple ... 4: 
4. Spike always mucronate. Stem more or less rough: 
E. hiemale, variegcitum and ramosissimum. 
— Spike gen. obtuse. Stem smooth or hardly at all rough 5 
5. Stem fairly thick, central hollow large, several times as 
large as the vallecular spaces. *) Sheaths with 15—20 teeth: 
E. limosum. 
— Stem rather slender; the central hollow as large or 
narrower than the vallecular spaces. Sheaths with 5 to 
15 teeth ......... 6 
6. Stem gen. terminated by a spike: the first internode of 
the branches much shorter than the corresponding cau- 
line sheath: E. palustre. 
— Stem without a spike; the first internode of the branches 
longer than the corresponding cauline sheath: E. arvense. 
OBS. Hybrid: E. arvense-limosum (litorale Kiihlw. inundatum Lasch.). 
128. Ophioglossese. 
680. Ophioglossum. Adder’s-tongue. XXIV, 9. 
1. Barren part of the frond oval-oblong, with entire edges, 
placed about the middle of the plant.—Damp meadows ; 
rare (wanting in G. S.). 6 . . vulgatum L. 2595. 
681. Botrychium. Meon-wort. XXIV, 9. 
1. Barren part of the frond (when well developed) always 
petioled, inserted near the base of the plant 2 
— Barren part of the frond sessile, placed about or above 
the middle of the plant . .... 3 
2. Barren part of the frond oval or obovate, rounded-ob¬ 
tuse, glabr., entire or incised.—Engelberg (Zabel) 
* simplex Hitch. 2596. 
— Barren part of the frond triangular in form, rather 
prolonged at the point, gen. 2-pinnatisect.—Chamouny. 6 
*rut3efolium A. Br. 2597. 
3. Cellules of the epidermis winding. Barren part of the 
frond triangular-oval, broader than long, 2-pinnatisect; 
segments of the second order anadromous (the first in 
the upper row, in the following species catadromous, 
i. e. the first in the lower row).—G. (Prattigau, oppo¬ 
site Sernauserbad). . . virginianum Sw. 2598. 
*) The channels opposite the furrows are called by this name. 
