THE SEED. 



117 



CHAPTER XIV 



THE SEED. 



5S2. The seed is the perfected ovule, having an embryo formed with- 

 in, which is the rudiment of a now plant similar in all respects to the 

 original. The seed consists of a nucleus or kernel invested with 



5SS. The integuments on coverings. The outer covering is the 

 testa, the inner the tegmen, as in the ovule. The latter is thin and 

 delicate, often indistinguishable from the testa. 



463 464 46i 462 460 



Seed of Water-Lily (Nympbsoa), enlarged section ; an., albumen ; a, the embryo contained 

 in the embryo-sac ; «, secundine or teamen ; p, primine or testa ; r, raphe , <i>; aril; m, ml- 

 cropyle ; /, funiculus. 463, Seed of Bean. 464, Same, one cotyledon with the leafy embryo. 

 461, Seed of Apple. 462, One cotyledon showing the raphe and embryo. 460, Fruit of Mirabi- 

 lis; embryo coiled into a ring. 454, Onion ; embryo coiled. 455, Convolvulus ; leafy embryo 

 folded. 450, Embryo of Cuscuta. 457, Typha. 45S, Ranunculus. 459, Hop. 



531. The testa is cither membranous (papery), coriaceous (leath- 

 ery), crustaceous (horny), bony, woody, or fleshy. Its surface is gen- 

 erally smooth, etc. (118, a). 



585. The coma must not eb confounded with the pappus, which is a modi- 

 fication of the calyx, appended to the perijarp, and not to the seed, as in the ache- 

 nia of the thistle, dandelion, and other Compositae. Its intention in the economy 

 of the plant cannot be mistaken, serving liko the pappus to secure the dispersion of 

 the seed, while incidently as it were, iu the case of the cottonseed, it furnishes 

 olothing and employment to a largo portion of the human race. • 



586. The aril is an occasional appendage, partially or wholly in- 

 vesting the seed. It originates after fertilization, at or near the hilum, 

 where the seed is attached to its stalk (funiculus). Fine examples are 

 Been in the gashed covering of the nutmeg, called mace, and in the scar- 

 let coat of the seed of staff-tree. In the seed of Polygala, etc., it is but 

 a smaH scale, entire or 2 -cleft, called caruncle. 



