haw , Oe 
The External Form of Plants. 7. ae 
pea and bean (Fig. 98, p. 70), the embryo contains a few 
other leaves besides the cotyledons. 
_ The relative position of the different parts of the embryo 
requires special notice. ‘The most common arrangement is 
that found in Crucifere, 
where the embryo is 
pleurorhizal, the  cotyle- 
dons lying flat one upon 
another, and the radicle 
upon the line which sepa- 
mites them, (big. 336). 
In the xotorhizal embryo 
(Fig. 337), the radicle lies 
upon the back of one of the 
cotyledons, which again lie 
flat one upon another. The fic. 335.—m- Fic. 336.— Pleurorhizal 
: ; . : bryo of Scotch embryo of Luzaria; I. 
embry O18 07 thop lozic (FE 1g. fir,with sixcoty- transverse; II. longitu- 
338) when the radicle lies eds. «. tc Re the 
in the hollow channel of ate 
the folded cotyledons. In the sféral embryo (Fig. 239); 
IIL. 
FIG. 337.—Seed of Neslea paniculata ; 1. entire; I1., IIT., sections in two different 
directions showing the notorhizal embryo (magnified). 
secs Wn Tm Neg : wee ee 
Fic. 338.—Seed of Evruca sativa poles entire tlh, Fic. 339.—Spiral embryo of 
III., sections in two different directions showing Bunias Erucago (magnified). 
the orthoplozic embryo (magnified). 
sal the cotyledons are laid flat upon one another and coiled 
spirally. Occasionally the embryo is doubly spiral. : 
