EMBRYO 



37* 



may persist up to germination (albuminous seeds, e.g. Buckwheat, 

 Castor Oil, most Monocotyledons). In a few plants (e.g. many 

 Caryophyllaceae) the nucellus is not entirely displaced by the 

 endosperm, a thin layer (perisperm) remaining, even in the ripe 



R 



FIG. 217. Embryology of various plants. A-D, Successive stages in the 

 development of the embryo of the Arrowhead (Sagittaria) (after 

 Schaffner). E, Longitudinal section of ripe achene of the Water 

 Plantain (Alisma) (original). F, Formation of several embryos (em.) 

 from a massive suspensor, by budding, in Erythronium americanum 

 (Liliaceae) (after Jeffrey). G, Proembryo, with massive suspensor, of 

 Lilium (after Coulter). H, Embryo of Tway blade (Lister a ovata) at 

 time when seed is shed (after Pfitzer). I, Proembryo of Spartium 

 junceum (Leguminosae) (after Guignard). J, Longitudinal section of 

 Orange pip (Citrus) (with two embryos) (after Wettstein). b., basal 

 cell ; Co., cotyledon ; /., funicle ; p., plumule ; pc. t pericarp ; r., 

 radicle ; 5., suspensor ; /., testa. 



seed, and functioning for the storage of food. The degree of 

 differentiation attained by the embryo, at the time when it enters 

 upon its resting-stage, varies considerably. Thus, in the Runner 

 Bean (Phaseolus), even the venation of the first pair of plumular 



