118 



THE SEED. 



587. The position of the seed in the pericarp is, 

 like that of the ovule, erect, ascending, pendulous, etc. 

 (§ 534). Likewise ia respect to its inversions, it is vrtho- 

 tropous, andtropous, amphitropous, and campylotropous 

 (§ 536), terms already defined. The anatiopous is by 

 far the most common condition. 



588. The hilum is the scar or mark left in 



the testa of the seed by its separation from the 



funiculus. It is com- 



monly called the eye, as 

 in the bean. In orthoy 

 tropous and c;mpyio- 

 tropous seeds, ihe hilum 

 || corresponds with the 

 chalaza (§535). In other 

 /|jf[\\\ conditions it does not, 

 465 464 463 461 460 462 and the raphe (§537) ex- 



460, Aril of Euonymus. 461, Aril of Nutmeg (mace). 462, tends between the two 

 Seed of Polygala, embryo, caruncle, e, (too small.) 463, Seed . . 



.ofCatalpa. 464, Seed of Willow. 465, Seed of CottoD. points, as in the ovules. 



589. The seed kernel may consist of two parts, the embryo and 

 albumen, or of the embryo only. In the former case the seeds are 

 albuminous, in the latter, exalbuminous, a distinction of great import- 

 ance in systematic botany. 



590. The albumen is a starchy or farinaceous substance accom- 

 panying the embryo and serving as its first nourishment in germina- 

 tion. Its qualities are wholesome and nutritious, even in poisonous 

 plants. Its quantity when compared with the embryo varies in every 

 possible degree; being excessive (Ranunculaceae), or about equal (Vio- 

 laceae), or scanty (Convolvulacese), or none at all (Leguminosae). In 

 texture it is mealy in wheat, mucilaginous in mallows, oily in Ricinus, 

 horny in coffee, ruminated in nutmeg and pawpaw, ivory-like in the 

 ivory-palm (Phytelephas), fibrous in cocoa-nut, where it is also hollow, 

 enclosing the milk. 



591. The embryo is an organized body, the rudiment of the future 

 plant, consisting of root (radicle), stem-bud (plumule), and leaves 

 (cotyledons). But these parts are sometimes quite undistinguishable 

 until germination, as in the Orchis tribe. 



592. The radicle is the descending part of the embryo, almost al- 

 ways directed towards the micropyle, the true axis of the seed. 



593. The plumule is the rudimentary ascending axis, the terminal 

 bud, located at the base of, or between 



594. The cotyledons. These, the seed-lobes, are the bulky, fari- 

 naceous part of the embryo, destined to form the first or seminal leavea 



