526 CXXXVIII. ALISMACEiE. Sagittaru. 



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. PAUCiFLoRLs. Pursh. (P. gramineura. Michx.) Grassy Pond-weed. 

 St. round, dichotomous, filiform ; lis. linear, alternate, sessile ; Jls. 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. zosterifolium. Schum.) 



SI. 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, ^ — r long, on a pedimcle 

 1 — 2' long, and bearing 5—25 flowers. Jl. 



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

 St. slender, branched, striate, flexuous; /r.<;. numerous and fascicled in the 



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

 the lower fls. remote; j9<?r/. filiform, long. — Plant submersed in deep water, bushy 

 and very leafy, N. Eng. 1 Middle States ! W. to Wis. Laphavi ! Leaves 4 — T by 

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

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



12. P. PLsiLLUs. Linn. 1 (P. pectinatum. Clark, MS.) Puny Pond-weed. 

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



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

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

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

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

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



Order CXXXVIII. ALISMACE^.— Alismads. 



Kerbs, aquatic. Lvs. paraUel-veined. Fls. racemose or paniculate. 



Fls. perfect or monoecious, regular, not on a .spadix. 



Perianth.— Cat. 3-sepaied, green. Cur. 3-petaled, colored (green in the suborder). 



Sta. detinite or indefinite, hypogynous. 



Oi'a.— Carpels several. 1-celIed and 1-seeded. Styles and stigmas several. 



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



Conspectus of the Gciicra. 



\ Flowers all perfect. Stamens 6 Alisma. 1 



( colored, sepals green. \ Flowers monoecious. Stimens indefinite. . . Sagittaria. 2 



•? S Anthers thick, short. Leaves cauline. . . . Triglochin. 3 



Petals ( green, like the calyx. I Anthers linear. Leaves all radical. . . Scfieuchzeria. 4 



1. ALISMA. 



Celtic alls, water ; the place it inhabits. 



Flowers $ ; stamens 6 ; ovaries and styles numerous, aggregated, 

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

 cent. Lvs. radical. Fls. paniculate. 



A. Plant.Igo. (A. parviflora. Ph.) Water Phnttain. 



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

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

 Leaves resemblingtho.se of the common plantain, 4 — 6' long, | 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 ba.se. Flowers 

 numerous. Petals 3, tinged with purple, roundi'^h, deciduous, larger than the 

 greon, ovate, persistent sepals. July. 

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



2. SAGITTARIA. 



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



Flowers c? ; cT with about 24 stamens ; 9 with numerous ovaries 



