126 



[SECTION 15. 



for dispersion by the winds. This is clear, not only from their evident 



adaptation to this purpose, but also from the fact that winged and tufted 



seeds are found only in fruits that split open at maturity, never in those 



jrifo that remain closed. The coat of some seeds is beset with 



/" v'.r\ long linirs or wool. Chiton, one of the most important vege- 

 table products, since it forms the principal clothing of the 



larger part of the human race, consists of the long and woolly hairs which 

 thickly cover the whole surface of the seed. There are also crests or other 

 appendages of various sorts on certain seeds. A few seeds 

 have an additional, but more or less incomplete covering, out- 

 side of the real seed-coats called an 



383. Aril, or Arillus. The loose and transparent 

 bag which encloses the seed of the White Water-Lily 

 (Fig. 418) is of this kind. So is the mace of the 

 nutmeg ; and also the scarlet pulp around the seeds 

 of the Waxwork (Celastrus) and Strawberry-bush 

 (Euonymus). The aril is a growth from the ex- 

 tremity of the seed-stalk, or from the placenta when 

 there is no seed-stalk. 



384. A short and thickish appendage at or close to the hilam in certain 

 seeds is called a CARUNCLE or STROPHIOLE (Fig. 419). 



385. The various terms which define the position or direc- 

 tion of the ovule (erect, ascending, etc.) apply equally to the 

 seed : so also the terms anatropous, orthotropous, campylotro- 

 pous, etc., as already denned (320, 321), and such terms as 



HILUM, or Scar left where the seed-stalk or funiculus falls 

 away, or where the seed was attached directly to the placenta 

 when there is no seed-stalk. 



RHAPHE, the line or ridge which runs from the hilum to the chalaza in 

 anatropous and amphitropous seeds. 



CHALAZA, the place where the seed-coats and the kernel or nucleus are 

 organically connected, at the hilum in orthotropous and campylotropous 

 seeds, at the extremity of the rhaphe or tip of the seed in other kinds. 



MICROPTLE, answering to the Foramen or orifice of the ovule. Compare 

 the accompanying figures and those of the ovules, Fig. 341-355. 



Fio. 415. A winged seed of the Trumpet-Creeper. 



Flo. 416. One of Catalpa, the kernel cut to show the embryo. 



Fio. 417. Seed of Milkweed, with a Coma or tuft of long silky hairs at one end. 



Fia. 418. Seed of White Water-Lily, enclosed in its aril. 



Fio. 418. Seed of Ricinus or Oastor-oil plant, with oarunole. 



