FORMS OF COTYLEDONS 



21 



base, as in Poterium (fig. 42) and Cuphea. Sometimes they 

 are large ; sometimes small. Generally they are leaf-like ; 

 but sometimes, as in Ehus Thunbergii (fig. 44), Sapindus 

 (fig. 43), and among English plants in the Oak, Nut, Pea, Bean, 

 Mercurialis perennis, 1 Melittis Melissophyllum, 2 Nymphaea, 

 Nuphar, Ehamnus Frangula, Trientalis, Daphne, &c., they are 

 thick and fleshy. 



FIG. 45. A, Fruit of Platanus, longitu- 

 dinal section, x 6 : w, woody part. B, 

 transverse section, x 12. 



FIG. 46. A, samara of Frax- 

 inus excelsior, nat. size, 

 with one half removed and 

 the seed pulled out: pa, 

 placental axis ; ao, abortive 

 ovule ; /, funicle. B, longi- 

 tudinal section of seed. In 

 germination the embryo 

 grows to the whole length 

 of the seed. 



Except where otherwise stated, c stands for cotyledon ; oc, outer cotyledon ; 

 ic, inner cotyledon ; ch, chalaza ; e, embryo ; /, funiculus ; h, hilum ; m, micropyle 

 p, endosperm ; r, radicle ; t, testa. 



NAREOW COTYLEDONS. 



Let us now begin with such species as have narrow 

 cotyledons, and see if we can throw any light on this cha- 

 racteristic. The problem is simple enough in such cases as 

 Platanus, where we have on the one hand narrow cotyledons 

 (fig. 8) and on the other hand a long narrow seed (fig. 45, p) 



1 Winkler, ' Ueber die Keimpflanze des Mercurialis perennis,' Flora, 1880. 



2 Irmisch, ' Zur Naturg. v. Melittis,' Bot. Zeit. 1858, p. 233. 



