224 COMMON CANADIAN WILD PLANTS. 



2. NAI'AS, L. NAIAD. 



N. flex'ilis, Rostk. and Schmidt. Stems very slender. 

 Leaves very narrowly linear, minutely serrulate. 



3. /A Y\i< ili:i/M.\, Miclieli. HORNED PONDWEED. 

 Z. palUS'triS, L. Fruit obliquely oblong, flattish and 

 somewhat incurved. Style half as long as the nutlet. 



4. ZOSTE'RA, L. EEL-GRASS. GRASS-WRACK. 

 Z. mari'na, L. Leaves obscurely 3-5-nerved. AtL Sea- 

 coast, in shoal water. 



II. PETALOI'DEOUS DIVISION. 



Flowers with a perianth coloured like a corolla. 



ORDER XCVIII. ALISMA'CE^E. (WATER PLANTAIN P.) 



Marsh herbs, with flowers having 3 distinct sepals and 

 3 distinct petals, pistils either apocarpous or separating at 

 maturity into distinct carpels, and hypogynous stamens 6- 

 many. Flowers on scapes or scape-like stems. Leaves 

 sheathing at the base either rush-like or, when broad, mostly 

 heart-shaped or arrow-shaped. 



Synopsis of the Genera. 



* Calyx and corolla both greenish. Carpels more or less united, bttt 



spreading at maturity. Leaves rush-like and fleshy, or 



grass-like. 



1. Ti-ijf lo'oliin. Flowers small, in a spike or close raceme, without 



bracts. Carpels united to the top ; when ripe, splitting away from 

 a central persistent axis. 



2. Sclieuchze'rla. A low bog-herb, with a creeping jointed rootstoCK, 



and grass-like leaves. Stamens 6. Carpels 3, globular, nearly 

 distinct. 



(These two genera are included in Naiadacese in Macoun's Catalogue.) 



** Calyx green, persistent. Corolla white. Pistil apocarpous. Leaves 

 with distinct blades and petioles. 



3. Alls' nia. Flowers perfect. Stamens usually 6. Carpels numerous, 



in a ring. Leaves all radical. Scapes with whorled panicle** 

 branches. 



