58.1 



THE SEED. 



198 



CHAPTER XII. 



THE SEED. 



172. The seed is the perfected ovule, having an 

 embryo formed within, which is the rudiment of a new 

 plant, similar in all respects to the original. The seed 

 consists of a nucellus or kernel, invested with the 

 integuments or coverings. The outer covering is the 

 testa, the inner the tegmen, as 



in the ovule. The latter is 

 thin and delicate, often indis- 

 tinguishable from the testa. 



173. The testa is either 

 membranous (papery), coria- 

 ceous (leathery), crustaceous 

 (horny), bony, woody, or fleshy. 

 Its surface is generally smooth, 

 sometimes beautifully polished, 

 as in Columbine, Indian-shot 

 (Canna), and often highly col- 

 ored, as in the Bean ; or it 

 may be dull and rough. It is 

 sometimes winged, as in Ca- 



talpa, and sometimes clothed with long hairs, as in 

 Silk-grass (Asclepias). Such a vesture is called the 

 Coma. Cotton is the coma of the Cotton-seed. 



174. The coma must not be confounded with the pappus ( 104), which is 

 a modification of the calyx, appended to the pericarp, and not to the seed, as 

 in the akenes of the Thistle, Dandelion, and other Composites. Its intention 

 in the economy of the plant can not be mistaken; serving like the pappus to 

 secure the dispersion of the seed, while incidentally, in the case of the Cotton- 

 seed, it furnishes clothing and employment to a large portion of the human 

 race. 



198, Aril of Nutmeg (mace). 199, Seed of 

 Catalpa. 200, Seed of Willow. 201, Seed of 

 Cotton. 



