526 CXXXVIII. ALISMACEiE. Sagittaria. 



ponds in N. H. and Mass. Stem long, branched, almost wholly enclosed in the 

 sheaths. Leaves 2 — i' by 2—3", very acute, somewhat crowded. 



9. P. PAUCiFLORUS. Pursh. (P. gramineum. Michx.) Grassy Pond-weed. 

 St. round, dichotomous, filiform ; Ivs. linear, alternate, sessile ; fis. few in 



a spadix. — A delicate species, in rivers, &c. Leaves numerous, obtuse, tapering 

 to the stipulate base, 2—3' long, a line wide, 1-veined, of a bright green color. 

 Peduncle an inch long, terminal, bearing 3—5 greenish fls. above the water, but 

 ripening the seeds below. 



10. P. coMPREssus. (P. zosteri folium. Schum.) 



St. compressed, ancipital, flexuous ; Ivs. broad-linear, obtuse ; spike short, 

 peduncle elongated. — A very distinct species, in ponds and rivers. Stem 1— 2f 

 long, branching, weak, flattened, green, with sheathing stipules above the nodes. 

 Leaves 3—4' in length, 2" wide, closely sessile, remote, the margins perfectly 

 parallel, ending in an abrupt point. Spadix terminal, i — 1' long, on a peduncle 

 1_2' long, and bearing 5—25 flowers. Jl. 



11. P. PECTiNATUs (and P. marinus. Linn.) Fennel-leaved Pond-weed. 

 St. slender, branched, striate, flexuous; Ivs. numerous and fascicled in the 



axils, long, narrowly linear, acuminate, on sheathing stipules; spikes cylindrical, 

 the lower fls. remote; ;?e^. filiform, long. — Plant submersed in deep water, bu.shy 

 and very leafy, N. Eng. 1 Middle States ! W. to Wis. Lapham ! Leaves 4—7' by 

 (less than) 1", thin, the midvein scarcely perceptible. Fruit large, purplish, 

 rough, a little compressed, neither carinate, nor umbilicate. Jn. 



12. P. PUsiLLUS. Linn. % (P. pectinatum. Clark, MS.) Puny Pond-weed. 

 St. filiform, flexuous, branched ; Ivs. linear-subulate, membranaceous, very 



acute, sessile, not narrower than the stipules ; spikes capitate, few-flowered ; fr. 

 ovoid-compressed, umbilicate each side.— Shallow waters, about Cincinnati. 

 Clark I A very delicate species, whollv submersed. Leaves 1 — 2' by i", a lit- 

 tle longer than the internodes. Spikes 3— 5-flowered, the pedimcles i' long. 

 Fruit with distinct pits, as in P. obrutus, and rather inflated. 



Order CXXXVIII. ALISMACE^.— Alismads. 



Uerls, aquatic. Lvs. parallel-veined. Fls. racemose or paniculate. 



Fls. perfect or monoBcious, regular, not on a spadix. i. j v 



Perianth— Cal. 3-sepaled, green. Cor. 3-petaled, colored (green m the suborder). 



Sta. definite or indefinite, hypogynous. , , „ , , . , 



Om.— Carpels several, 1-celled and l-seeded. Styles and sUgmasseweral . . 



Fr. dry, indehiscent. Seeds straight or curved, destitute of albumen. Genera 5, species 16 ? 



Conspectus of the Genera. 



^ Flowers all perfect. Stamens 6 Alisma. 1 



( colored, sepals green. ( Flowers monoecious. Stamens indefinite. . . Sagittaria. 2 



) ' ^ ^ Unthers thick, short. Leaves cauUne. . . . Triglochin. 3 



Fetals(green, like the calyx. ^Anthers linear. Leaves aU radical. . . . Scheuchzerta. 4 



1. ALISMA. 



Celtic alls, water ; the place it inhabits. 



Flowers $ ; stamens 6 ; ovaries and styles nnmerou-s, aggregated, 

 becoming in fruit numerous, distinct, compressed achenia. — % caules- 

 cent. Lvs. radical. Fls. 'paniculate. 



A. Plantago. (A. parviflora. Ph.) Water Plantain. 

 Lvs. oval, abruptly acuminate or cuspidate, subcordate; ach. obtusely 3- 

 cornered. — A common, smooth, handsome inhabitant of ponds and ditches. 

 Leaves resembling those of the common plantain, 4—6' long, f as wide, ending 

 in a short, abrupt point, 7 — 9-veined, entire, on long, radical petioles. Scape 

 1— 2f high. Branches of the panicle verticillate, with bracts at base. Flowers 

 numerous. Petals 3, tinged with purple, roundish, deciduous, larger than the 

 green, ovate, persistent sepals. July. 



/?. parvijlora. Torr. Lvs. oval, acuminate, 5 — 7-veined; fls. small. 



2. SAGITTARIA. 



Lat. sagitta, an arrow ; from the peculiar form of the leaf. 



Flowers § : J" with about 24 stamens ; 9 with numerous ovaries 



