492 ALISMACi:^. (WATEU-PLANTAIN FAMILY.) 



Leaves all from the root, several-ribbed, with eonneeted veinlets. Scape with 

 whorled panicled branches. Flowers small, wiiite or pule rose-color. (The 

 Greek name ; of uncertain derivation.) 



1. A. Plant^gO, L., var. Araericknum. Koot perennial ; leaves lon;>- 

 petioled, ovate, ol)lon^^ or lanceolate, pointed, mostly rounded or heart-shaped 

 at the base, 3 - 9-ncrvcd ; panicle loose, compound, many-flowered (l°-2° 

 lonji:) ; carpels obliquely obovatc, forming an obtusely triangular whorl in fruit 

 (A. trivialis and parviflora, Pursh.) — Shallow water. July- Sept. (Eu.) 



4. ECHINODORUS, Kichard, Engclmann. 



Flowers perfect. Petals imbricated in the bud. Stamens 6-21 or more 

 Ovaries several or many, imbricated in a liead, forminj; thick and ribbed 

 achenia in fruit, often beaked with a projecting persistent style. — Habit inter- 

 mediate between the preceding genus and the following. Fl. summer and 

 autumn. (Name from ()(iva)8rjs, pric/c/i/, or from f)(lvos, and 8op6s, a leathern 

 bottle, applied to tlie ovary, which is in most species armed with the persistent 

 style, so as to form a sort of prickly head of fruit.) 



Genus elaborated for this work by Dr. Engelmaxn. 



1 . E. parvulus, Engclm. Lpuvcs lanceolate or spafulate, acute (^' - 1 i' long, 

 including the jtctiole) ; shoots often creeping and proliferous; scapes (l'-3' 

 high) bearing a 2-8-flowered umbel; pedicels reflexed in fruit; stametis 9; 

 styles much shorter than the ovari/ ; achmin hrakless, many ribbed ; root aimual. — 

 In mud, Cambridge, Mass. James, and Michigan to 111. &c. — Flower 3" broad. 



2. E. rOStr^tUS, Engelm. Leares broddli/ heart-shaped, olitiise, nerved {l-- 

 3' long, excluding the petiole) ; scape erect, longer than the leaves, bearing a 

 branched panicle of ])i:oliferous umbels ; stamens 12 ; styles lonejer than the ovary ; 

 achenia beaked, many-ribbed ; root annual. (Alisma rostrata, Niitt.) — Swamps 

 and ditches, Illinois and southward. — Plant from 3' to 2° high. Flower 5" 

 wide. Head of fruit ovoid, 3" wide. 



3. E. radicans, Engclm. Leaves somewhat truncatelj' broadly heart- 

 shaped, obtuse, nerved (3' -8' broad, long-petioled) ; stems or scapes prostrate, 

 creeping (2° -4° long), proliferous, bearing many whorls of flowers; stamens 

 about -l ; styles shorter than the ovary ; achenia short -beaked, the keeled back 

 denticulate. (Ali.sma radicans, Xutt.) — Swamps, Illinois and southward. — 

 Flowers G"-9" in diameter. 



5. SAGITTARIA, L. Akrow-iie.vd. 



Flowers monwcious, or often dicecious in Xo. 2, and polygamous in No. 3. 

 Petals imbricated in the bud. Stamens indelinitc, rarely lew. Ovaries many, 

 crowded in a spherical or somewhat tri.ingular depressed head on a globular 

 receptacle, in fruit forming flat membranaceous winged achenia. — Marsh or 

 aquatic, perennial, stolonifcrous herbs, with milky juice and fibrous roots; the 

 scapes sheathed at the base by the bases of the long cellular ijctioles, of which 

 the primary ones, and sometimes all of them, arc flattened, nerved, and desti- 

 tute of any proper blade (i. e. are phyllodia) : when present the blade is arrow- 

 shaped or lanceolate, nerved and with cross veinlets as in Alisma. Flowers 



