CERATOPHYLLE^. (lIOllNWORT FAMILY.) 745 



3. P. nigra, L. 5 Black Poplar. 10 to 30; Iranches spreading. 

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



triangular-rlioinboid^ Iroader than long^ minutely serrulate — ^m'wiff 



Coelesyria ; near Damascus. ^ 



4. P. pyrainidalis, Hoz. 5 Lombardy Poplar. 10 to 20; 



Iranches erect, forming a narrow-conical comiis. Leaves glabrous, glossy, 

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

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

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

 is of Cupressus sempervirens. 



Ordeu CIL CERATOPHYLLE^, Gray. (Hork wort Family). 



Aquatic lierhs^ with %ohorled, finely dissected leaves, 

 and onimtte, axillary, sessile, ononoecious floioers, witliout 

 anyflo7xd envelopes, except an ^-12-cleft involiLcre or ferigo- 

 nium, the j[?^5^^7Z(2^6 a simple, \-celled ovary, 'loith a 

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

 hryo with 4 cotyledons and a conspicuous plumule — Stami- 

 nate fi.oioers. 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 floioers. Divisions of perigo- 

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

 subulate. J^utlet coriaceous, beaked with the style, and 

 often prielvly at base. Albumen 0. 



€ERATOPHYl.EUM, L. Hornwort. 



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

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

 entire, dentate, or incised lobes. 



C deiiiersiiiii, L. 2i! As above — Jordan Valley. Seldom seen 

 in fruit. 



Var. commune, Gray. Fruit wingless, with a short spine or 

 tubercle at the base on each side. 



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

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



Subclass II. GYMNOSPERM/E. 

 DI-POLYCOTYLEDONS. 



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

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

 fertilized by the direct application of the pollen. Kepresented 

 with us by two orders, Gnetaccj^fi witli two cotyledons, and 

 Conifern3 with two to twelve. 



