526 . CXXXVIII. ALlSMACEiE. Sagtitaria, 



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. IMichx.) Grassy Pond-weed. 

 St. round, dichotomous, filiform ; Ivs. 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. zosteri folium. Sclium.) 



St: compressed, ancipital, flexuous; !vs. broad-linear, obtuse; spike short, 

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

 lung, branching, weak, Sattcned, 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, J — I'long, on a peduncle 

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



11. P. PECTiNATUs (and P. marinus. U.nn.') Fennel-leaved Pond^L-eed. 

 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 v/ater, bushy 

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

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

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



1-2. P. posiLLUs. Linn. 1 (P. pectinatum. Clark, MS.) Puny Pond-^meed. 



SI. 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! A very delicate species, wholly submersed. Leaves 1 — 2' by ^", a lit- 

 tle longer than the internodes. Spikes -S — 5-flowered, the peduncles J' long. 

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



Order CXXXVIII. ALISMACE^.— Alismads. 



Heris, aquatic. Lvs. parallel-veined. Fis. racemose or paniculate. 



Fls. perfect or moncDcious, regular, not on a spadi.x. 



Perianrfi.—Cal. 3-sepaled, green. Cor. 3-petaled, colored (green in the 9uborder>. 



Sla. definite or indefinite, hypogynous. 



Owa.— Carpels several, 1-celled and l-seeded. Styles and stigmas several. 



fV. dry, indehiscent. Seeds straight or curved, destitute of albumen. Genera 5, species 167 



Conspectus of the Genera. 



^ Flowers all perfect Stamens 6 Alisma. 1 



f eoloted, aepab green. \ Flowers monoecious. Stamens indefinite. . . Sa^ttarifi. 2 



< C Anthers thick, short. Leaves cauline. . . . I'riglochin. 3 



Petals ( green, like the calyx. { Anthers linear. Leaves all radical. . . . Scheuchztria. 4 



1. ALISMA. 



Celtic alis, water ; the place it inhabits. 



Flowers 5 ; stamens 6 ; ovaries and styles numerous, aggregated, 

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

 cent. Lvs. radical. Fls. paniculate. 



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



Las. oval, abruptly acuminate or cuspidate, subcordate; ax.li. obtiisely 3- 

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

 Leaves resembling those 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. Brai^hes of the panicle verticillate, with bracts at base. Flowers 

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

 green, ovate, persistent sepals. Julj'. 

 /?. parviflora. Torr. Jjvs. oval, acuminate, 5 — 7- veined ; fls. small. 



3. SAGITTARIA. 



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



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



