CERATOPHYLLE^. (llOllNWORT FAMILY.) 7i5 



3. P. ilig^ra, L. 5 Black Poplar. 10 to 30 ; hranches spreading. 

 Leaves glabrous, glossy, of the same color on both sides, deltoid to 

 triangular-rliomloid^ Iroader tlian long, minutely serrulate — ^^x\ng — 

 Coelesyria ; near Damascus. 



4. P. pyramiclali§, Roz. 5 Lombardy Poplar. 10 to SO; 



Iranclies erect, Jorming a narroic- conical conius. 'Leaves glabrous, glossy, 

 of the same color on both sides, rhombic, as long as Iroad, truncate at 

 base, serrulate — Sirring — Coelesyria and Antilebanon valleys. Pro- 

 bably introduced. Probably a form of the last, as the Cemetery Cypress 

 is of Cupressus sempervirens. 



Order CII. CERATOPHYI^LE^, Gray. (Horn wort Family). 



Aquatic he7'hs, vntli wliorled^ fi^'^cly dissected leaves^ 

 and minute, axillary, sessile, monoecious flowers, loitJiout 

 any floral envelopes, except an S'12-cleft involucre or p^rigo- 

 nium, the pistillate a shnple, 1-celled ovary, roith a 

 suspended, orthotropous ovule, the seed filled with an em- 

 bryo lolth 4: cotyledo7is and a conspicuous plumide — Stami- 

 nate flowers. Divisions of involucre linear, 2-3-dentate at 

 tip. Stamens 12-15, anthers subsessile, oblong - obovate, 

 notched at tip, 2-celled, the cells half-divided by an in- 

 complete septum. Pistillate flowers. Divisions of perigo- 

 nium linear, entire. Ovary ovate ; style straight ; stigma 

 subulate. Nutlet coriaceous, beaked with the style, and 

 often prickly at base. Albumen 0. 



CERATOPHYI.EUM, L. Hornwort. 



Aquatics as above, much branched, somewhat rigid, the stems and 

 branches nodular-joiDted, the leaves sessile, 2-3-forked into capillary, 

 entire, dentate, or incised lobes. 



C. c1einer.*^iiiii, L. 2f As above — Jordan Valley. Seldom seen 

 in fruit. 



Var. coiniuiiiie, Gray. Fruit wingless, with a short si)iue or 

 tubercle at the base on each side. 



Var. ecliiiiatiiiii, Gray. Fruit .000 long, rough-pimpled on the 

 sides, narrow-winged, the wing spiny-toothed. 



SujicLAss II. GYMNOSPERMyE. . 

 DI.POLYCOTYLEDONS. 



Pistil represented by an open scale or leaf, or ; the 

 ovule or seeds therefore naked (without a pericarp), and 

 fertilized l)y the direct application of the pollen. Eepresented 

 with us by two orders, Gnetacea^ witli two cotyledon:^, and 

 Conifera3 with two to twelve. 



97 



