TYPHACE^. 219 



cleft in the edge of the frond, or from the npper snrfaoe. 



Fruit a, 1-7-seeded utricle. The flowers are rarely to be 



seen. 



Synopsis of the Genera. 



1. liem'ua. Flowers from a cleft in the edge of the frond, usually 2 of 



a single stamen each, and 1 of a simple pistil, the three surrounded 

 by a spathe. Roots several or only one. 



2. Wolfflf'la. Flowers from the centre of the upper surface of the 



frond, only 2 ; one of a single stamen, the other of a simple pistil. 

 Moots none. The smallest of flowering plants. 



1. LGSIXA, L. Duckweed. 



1. L. polyTPhi'za, L. {Spirodela polyrrhiza, Schleiden.) 

 iTrouds round-obovate, green above, purplish beneath, mostly 

 7-nerved. Rootlets several. — Common in ponds and pools. 



2. L. trisul'ea, L. Fronds oblong to oblong-lanceolate, 

 half an inch or more long, narrowed at the base into a 

 slender stalk, denticulate at the tip, obscurely ' 3-nferved. 

 Rootlet single, often wanting. — Ponds and springy places. 



3. L. minOP, L. Fronds round to elliptic-obovate, very 

 small. Rootlet single. — Stagnant waters. 



8. TVOIFF'IA, Horkel. 



1. W. Columbia'na, Karsteu. Globular or nearly so, 

 light green all over, not dotted. — Stagnant waters, usually 

 rather below the surface. 



2. W. BFasllien'siS, Weddell. Oblong, deep green above, 

 pale below, dotted all over with brown. — "With the last, but 

 floating. 



Obdeb XCVI. TYPHA'CE^. (Cat-tail Family.) 



Aquatic or marsh herbs with linear sword-shaped leaves, 

 erect or floating, and monoecious flowers, either in separate 

 heads or on different parts of the same spike or spadix, but 

 without a, spathe, and destitute of true floral envelopes. 

 Fruit an achene, 1-seeded. 



Synopsis of tbe lienera. 

 1. Typlia* Flowers in a very dense and long cylindrical terminal 

 spike, the upper ones staminate, the lower pistillate, the ovaries 



