492 ALISMACE^E. ( WATER-PLANTAIN FAMILY.) 



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

 whorl ed panicled branches. Flowers small, white or pale rose-color. (The 

 Greek name; of uncertain derivation.) 



1. A. Plantago, L., var. Amerieanum. Root perennial ; leaves long- 

 petioled, ovate, oblong, or lanceolate, pointed, mostly rounded or heart-shaped 

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

 long) ; carpels obliquely obovate, forming an obtusely triangular whorl in fruit. 

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



4. ECHINODORITS, Richard, Engelmann. 



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

 Ovaries several or many, imbricated in. a head, forming 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 e^ii/coS//?, prickly, or from \lvos, and So/jos, a leathern 

 bottle, applied to the 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. ENGELMANN. 



1. E. parvulus, Engelm. Leaves lanceolate or spatulate, acute ('-!' long, 

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

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

 styles much shorter than the ovary ; achenia beakless, many-ribbed ; root annual. 

 Margin of ponds, Michigan to Illinois and westward. Flower 3" broad. 



2. E. rostratUS, Engelm. Leaves broadly heart-shaped, obtuse, nerved (!'- 

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

 branched panicle of proliferous umbels ; stamens 12 ; styles longer than the ovary ; 

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

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

 wide. Head of fruit ovoid, 3" wide. 



3. E. radicans, Engelm. Leaves somewhat truncately 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 21 ; styles shorter than the ovary ; achenia short-beaked, the keeled back 

 denticulate. (Alisma radicans, Nutt.) Swamps, Illinois and southward. 

 Flowers 6" - 9" in diameter. 



5. S>GITTARIA, L. ARROW-HEAD. 



Flowers monoecious, or often dioecious in No. 2, and polygamous in No. 3. 

 Petals imbricated in the bud. Stamens indefinite, rarely few. Ovaries many, 

 crowded in a spherical or somewhat triangular depressed head on a globular 

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

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

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

 the primary ones, and sometimes all of them, are 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 



