354 HYDROCnARIDACKiE. 



A. Plant AGO, L. Common Water- Plantain. 



Leaves orate, oblong, or lanceolate, narrowed rounded or somewhat cordate at 

 the base, 3 to 9-nerved, on long petioles-; panicle loose, compound, many-flowered. 



Ditches and marshy places, common. July, Aug. Scape 1 to 2 feet high. Leave* 

 A- to 6 inches long, % a3 wide. 



4. SAGrlTTAKIA, Linn. Arrow-head. 



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



Flowers monoecious, rarely dioecious or perfect. Petals 

 3. Sepals numerous (about 14). Ovaries many, collect- 

 ed in a spherical head on a globular receptacle, in fruit form- 

 ing membranaceous achenia, covered with the persistent 

 style. — Marsh or aq^zafic herbs, with milky 'juice and fibrous 

 roots, radical, mostly sagittate leaves sheathing at the base tlie scapes, 

 which bear the white or whitish flowers in 3s. 

 Sec. r. Sagittakia., proper; Flowers monoecious, rarely di»ciou3. 



1. ST. variabilis, Eageltm MSS. Gray. Common 

 Arrow-head* Variable Arrow-head. 



Leaves triangular-arrow-shaped, or entire, oblong, lanceolate, linear, and some- 

 times mere naked petioles ; scape* simple. 



Pitches, pools, streams, and moist grounds, eommon. July, Aug. Petals white. 

 "This with its- Protean varieties of which almost every pool and stream furnishes 

 a goodly number, embraces many nominal species of authors, and may safely be 

 held to include all that are found within out limits," Gray. The largest forms 

 bear sagittate leaves 12 inches or more long and 7 wide," others have both the 

 main blade and the lobes linear, many bear entire leaves, or else mere naked pe- 

 tioles; the smallest forms being only from 3 to 5 inches high. 



Sko n. EcHiN0Dor.us, Richard, Engelmann, in Gray. Flowers perfect. Sta» 

 mens 7 to 21. 



2. S, PITSILLA, Nutfc. Dwarf Arrow-head. 



Leaver linear, obtuse and short, with fallacious summits; seape simple, about m 

 long as the leaves, umbellately 3 to S flowered, some of them becoming proliferous- 

 runners; pedicels elongated, recurved; petals inversely heart-shaped; stamen* 

 about 9 ; styles much shorter than the evades-. 



Muddy margins of ponds and streams. Aug. Scape 2 to 4 inches high. Leave* 

 rarely ever subulate 1 to 2 inches long, scarcely a lice wide. Flowers 3 to 6, 

 each ripening 8 to 15 carpels. 



Order IIG. K£BROCKAKn)lLGEM.~Frog's-bti Family, 



Aquatit heris, with diaci&ns or poTygantous rtgular flowers on teapeJike peduncle* 

 from a spathe, and simple or double floral envelopes, which in the fertile flowers art 

 ttntted into a tube and coherent with the 1 to 6<elled ovctry. Stamkxs 3 to 12, di#- 

 Cnet, ormonadelphous: axthebs 2-oeUe<L Stxojlu 3 te §. Paurr ripening wider 

 p, iadehiscent, manynseeded. 



I. UDORA, Nute. Wateh-weei* 



Or. udor, water ; in allusion to Its place of growth. 



Polygamous Flowers solitary and sessile, from s sessile 



