MARSILEACEAE 



49 



5. B. obliquum and vars. x %. 



saiTonal, ternate and variously decompound with stalked divisions, these ovate- 

 oblong, acntish, usually two or tliree times as long as broad, crenate-serrulate, 

 obliquely cordate or subcordate ; fertile seg- 

 ment erect, 2-4-pinnate. (i^. ternatum, var. 

 obliquum Milde.) — Pastures and open woods, 

 N, B. to Ont, Minn., and south w. Fig. 5, a. 

 Tolymorphous. The chief forms are : Var. 

 ONEiDENSE (Gilbert) Waters. Fig. 5, b. Ulti- 

 mate divisions broadly oblong, rounded at the 

 apex, crenulate-serrulate. — Vt. (3Iiss Gilmaii) 

 to centr. N. Y. {Gilbert, Haberer), etc. Var. 

 tenuif6lium (Underw.) Gilbert. Divisions 

 few, usually 9, thin ; otherwise much like the 

 typical form. ■ — N. Y. (ace. to Gilbert); Mo. 

 (Bush), and south w. to the Gulf. Var. elon- 

 GATUM Gilbert & llaberer. Fig. 5, c. Divisiona 

 lanceolate, elongated, acute. — ]\lass. to centr. 

 N. Y. and D. C. Var. dissectum (Spreng.) 

 Clute. Fig. 5, d. Divisions ircisely many- 

 toothed. — Often with the typical form in N. E. , 

 N.Y., andO. 



6. B. ternatum (Thunb.) Sw., var. intermedium D. C. Eaton. Stout, 

 decidedly fleshy, loosely pubescent to subglabrous, 1.5-4 dm. high; habit and 



fertile segment as in the preceding ; sterile segment becoming 

 large (sometimes 2 dm. broad), its ultimate divisions numer- 

 ous, ovate or obovate, commonly subcuneate or semicordate 

 at the base, crenulate and more or less lobed, usually obtuse 

 or rounded at the apex. (Including var. australe D. C. 

 Eaton, as to Am. plant.) — Sandy soil, pastures and open 

 woods, common, N. E., N. Y., and (?) n. Mich. Fig. 6. 

 Passing insensibly into var. EUTAErdLiUM (A. Br.) D. C. 

 Eaton. More slender, rarely over 1.7 dm. high, sterile 

 segment commonly about 5 cm. broad, its divisions few, 

 broadly ovate, the lowest sublunate. {B. Matricariae Spreng. ; 

 B. rutaceum Sw.) — Nfd. to s. N. H., and n. Mich. (Eurasia.) 



§ 2. OSMUNDOPTEEIS Milde. Base of the stalk {contain- 

 ing the bud) open along one side; sterile segment mem- 

 branaceous; the cells of the epidermis flexuous. 



7. B. virginianum (L.) Sw. (Rattlesnake Fern.) Fronds 3-6 dm. tall, 

 ample ; sterile segment sessile above the middle of the plant, broadly triangular, 

 thin and membranaceous, ternate; the short-stalked j^rimar?/ d/v/s/ons once or 

 twice pinnate, and then once or twice pinnatifid ; the oblong lobes cut-toothed 

 toward the apex ; veins forking from a midvein ; fertile part 2-3-piunate. — 

 Rich woods, common. June, July (Widely distr.) 



6. B.tern.,v. interto 



MARSILEACEAE 



Perennial plants rooted in mud, having a slender creeping rhizome and either 

 filiform or '^-parted long-petioled leaves ; the somewhat crustaceous several-celled 

 sporocarps borne on peduncles which rise from the rhizome near the leaf-stalks^ 

 or are more or less consolidated with the latter, and contain both macrospores 

 and microspores. 



1. MARSILEA L. 



Submersed or emersed aquatic plants. Leaves 4-foliolate. Sporocarps with 2 

 teeth near the base, 2-celled vertically, with many transverse partitions, splittinp 

 irto 2 valves at maturity, and emitting an elastic cord or band of tissue, which 



CRAY'S MANUAL— 4 



