Order 135.— ALISMACE^E G77 



clustered at the nodes, on long pedicels; stam. 18 — 24; heads of carpels ovoid, 

 achenia short-beaked, very numerous (100 — 200). — U Swamps, W. 111. (Engel- 

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

 3 — i' t strongly heart-shaped. Scapes several, 2 — if long, producing roots and 

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

 bling those of Sagittaria. Jn., Jl. (Alisma, Nutt.) 



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

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

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

 ribbed and beaked. — J) River swamps, 111. near St. Louis (Engelm.) S. to Ark. 

 Much smaller than the preceding. Lvs. 1 — 3' long, petioles 2 — i'. Scapes 1 — 3t 

 Flowers about half as large as in Sagittaria. (Alisma, Nutt.) 



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

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

 stam. 9 ; heads of carpels depressed-globular; ach. abovi 20, beakless. — (D Muddy 

 shores, 111., Mo. to Mich. (Engelm.). Plant a few inches (1 — 3 or 4') high, often 

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

 diameter. 



3. SAGITTARIA, L. Arrow-head. (Lat. sagitta, an arrow ; from 

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

 als larger, colored, asstivation imbricate ; stam. oo ; ovaries very nu- 

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

 beaked achenia, — Acaulescent marsh herbs, with a 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, 2 



J Fertile pedicels as long as the sterile, (a) 



a Filaments longer than the anthers. Lvs. not sagittate No. 8 



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



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



1 S. variabilis Engelm. Lvs. generally sagittate ; scape 12-angled, upper fls. 

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

 longer than the anthers ; ach. obovate, 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 2f, 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. sagittifolia, 

 Ed. 1, &c, nee. Ix, from which it diners, according to Dr. Engelmann, in the char- 

 acters emphasized above.) 



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



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

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

 c5. gracilis. Lvs. linear, with linear, long, acute, spreading lobes. 

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



2 S. heterophylla Ph. Lvs. smooth, linear-lanceolate, rarely some of them ellip- 

 tical and sagittate ; scape simple, weak ; bracts roundish, obtuse ; upper fls. sterile, 

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

 rowly obovate, long-beaked. — Muddy shores, comm«n S. and "W. Leaves almost 

 as 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. Fls. large, 12 

 to 16" diam., white. July. 



(3. UIGIDA. Plant rather rigid in habit, erect ; lvs. narrowly lanceolate ; acute 

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



y. angustifoua. Lvs. nearly linear, delicate, often floating as well as the 

 weak, elongated scape. 



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

 ing at base to a very long petiole; scape tail, branched; fls. in 3s, all long-pedi- 



