Oedee 135.— ALISMACEjE 677 



iclaetered at tho nodes, on long pedicels; atam. 18 — 24; heads of carpels ovoid, 

 adienia short-beaked, very nuoierous (100 — 200). — y Swamps, W. IlL (Engel- 

 mann in Gray's Manual) S. to Ga (Mettauer) and La. (Hale). Lvs. 5 — 12' by 

 3 — T, strongly heart-shaped. Scapes several, 2 — if long, producing roots and 

 small leaves as well as flowers at the upper joints. Flowers white, much resem- 

 bling those of Sagiltaria. Jn., Ji. (Alisma, Nutt.) 



2 E. rostratus Engelm. Leaves ovate, rather acute, cordate, about 5-veined, the 

 later ones obkrag, all long-petioled ; scapes erect, much exceeding the leaves, 

 sha/rply angled; stam. 12; heads of carpels globular; ach. numerous (100), strongly 

 ribied and beaked. — ® Kiver swamps, 111. near SL Louis (Engelm.) S. to Ark. 

 Much smaller than the preceding. Lvs. 1 — 3' long, petioles 2 — i'. Scapes 1 — 3f. 

 Flowers about half aa lai'ge as in Sagittaria. (Alisma, Nutt.) 



3 B. parvula Engelm. Dwarf; leaves elliptic-lanceolate, very acute, tapering to a 

 peiioie of equal length; scapes erect, 3 — 6-flowered; pedicels reflexed in fruit; 

 gtam. 9 ; heads of carpels depressed-globular ; ach. about 20, fteoAks*.— <D Muddy 

 shores. III, Mo. to Mich. (Engelm.). Plant a few inches (1 — 3 or 4') high, often 

 stoloniferoua. Leaves, excluding petiole, less than 1' long. Fls. about 3" 

 diameter. 



3. SAGITTARIA, L. Arbow-hkad. (Lat. sagitta, an arrow ; from 

 the peculiar form of tho leaf.) — Flowers 8 , rarely ? i ; sepals 3 ; pet- 

 als larger, colored, ajstivation imbricate ; stam. oo ; ovaries very na- 

 raerous, crowded into a head, forming in fruit as many flat, margined, 

 beaked achenia. — Acanlescent marsh herbs, with ii milky juice. Lvs. 

 commonly arrow-shaped, often lanceolate, linear, or even reduced to 

 mere petioles. Scapes with fls. in whorls of 3s, the lower perfect. 

 Petals white. 



§ Lower (fertile) pedicels much shorter than the upper (sterile) ones Nos. 1, 'I 



§ Fertile pedieela as long as the sterile, (a) 



a Filameuta longer than tlie anthers. Lvs. not sagittate , No. ^ 



a Filaments very short.— Leaves lanceolate and linear, mostly Nos. 4-— 6 



— Leaves oval -obtuse, sagittate at base No. 7 



X S. variabilis Engelm. Lvs. generally sagittate ; scape 12-angled, .uppssr fis. 

 sterile, on pedicels but twice longer than those of the lower fertile fls. ; fil. glabrous, 

 longer than the anthers ; ach. obovaie, with a conspicuous, averted beak. — A curious 

 aquatic, conspicuous among the Rushes and Sedges of sluggish waters. Can. and 

 U.'S. Lvs. 3 to 10', the lobes about as long as the lamina, petioles much longer. 

 Scape 10' to 21, simple or branched, 3 of the angles prominent. Fls. mostly in 3s, 

 with ovate, slender-pointed bracts, often dioecious. Petals roundish, showy, 

 wholly white. Jl., Aug. The leaves are exceedingly variable. (S. sagittifoha, 

 Ed. 1, Ac, noc. L., from which it differs, according to Dr. Engelmann, in the char- 

 acters emphasized above.) 



/?. OBTUSA. Lvs. large, broadly ovate, sagittate, apex obtuse; fls. diascious. — 

 A large form. Mid., W. and S. States. (S. obtusa Willd.) 



y. LATIFOLIA. Lvs. large, broad-ovate, acute, with ovate, acuminate lobes. 



t'. GEACILIS. Lvs. linear, with linear, long, acute, spreading lobes. 



e. PCBESOENS. Plant pubescent in all its parts ; lvs. and their lobes ovate. 



2 S. heteroph;^lIa Ph. Lvs. smooth, linear-lanceolate, rarely some of them ellip- 

 tical and sagittate ; scape simple, weak ; ftrocis roundiih, obtuse ; upper fls. sterile, 

 on long pedicels, the lowest whorl fertile, almost sessile; fil very sliori; ach. nar- 

 rowly obovate, long-beaked. — Muddy shores, common S. and W. Leaves almost 

 us variable as in No. 1, but the other marks are very distinctive. Stalks If to sev- 

 eral, according to the depth of water. Blades 5 to 10' in length, i'ls. lai'ge, 12 

 to 16" diam,, white. July. 



^. EIQIDA. Plant rather rigid in habit, erect ; lvs. narrowly lanceolate ; acute 

 at apex, acute or obtusish at base. — Lake shores. (S. rigida Ph.) 



y. ANQUSTIFOLIA. Lvs. nearly -linear, deUcate, often floating as well as the 

 weak, elongated scape. 



3 S. lancifblia L., Mx. Lvs. lance-oblong, acutish, feather-veined, long-taper- 

 iag at base to a very long petiole ; scapo tall, branched ; fls. in 3s, all long-pedi- 



