308 THE SEED. 



inconspicuous, as in the ripe seed of Magnolia, where it is at 

 length completely merged and imbedded in the fleshy drupaceous 

 testa, as shown in Fig. 670-672. 



. 596. Crest-like or other appendages are not uncommon either 

 on the rhaphe or at the hilum. These are outgrowths produced 

 during the deveiopment of the ovule into the seed. In Sangui- 

 naria, such a crest develops from the whole length of the rhaphe 



(Fig. 673) : in Dicentra, Corydalis (Fig. 674), &c., from some 

 part of it, mostly from its base next the hilum, or from the 

 hilum itself, or even from just below it. Such an appendage, 

 especially when attached to the base of the seed, is named a 

 STROPHIOLE. A similar and commonly a wart-shaped appendage 

 in Euphorbia, Ricinus (Fig. 675), &c., is produced by an out- 

 growth of the external orifice of the ovule, the micropyle of the 

 seed. This properly takes the name of CARUNCLE. But the 

 two terms are not always discriminated. By further develop- 

 ment, either of these may give rise, in certain seeds, to an acces- 

 sory covering called 



597. The Aril or Arillus. This term, rather vaguely employed 

 by Linnaeus, was first well defined by Gaertner. The true arillus 

 is an accessor}' seed-covering, more or less incom- 

 plete, formed between the time of fertilization and 

 the ripening of the seed, by a growth from the apex 

 of the funiculus (when there is any) at or just be- 

 low the hilum, in a manner similar to that in which 

 the coat or coats of the ovule are formed. That 

 of N3-mphaaa (Fig. 676) is a typical example ; only 

 the arillus is developed from the funiculus at a point distinctly 

 below its apex : here a ring forms, which grows into a cup, and 

 this is soon extended into a sac, loosely enclosing the seed, and 

 open at the top. This is membranaceous ; commonly it is fleshy. 

 When there is absolutely no funiculus, the aril may originate 

 from the placenta, as it does in Podophjllum, in which most of 



FIG. 672. Anatropous seed of Sarracenia purpurea, with very salient rhaphe. 673. 

 Same of Sangiiinaria or Bloodroot, with rhaphe crested for its whole length. 674. Seed 

 of Corydalis aurea, with crest or strophiole, attached at or near the hilum. 675. Seed 

 (suspended) of Ricinus, with its caruncle. 



FIG. 676. Seed of White Water-Lily, Nymphsea odorata, in its loose and thin arillus. 



