LKSSON 21.] 



ITS COATS OK COVKIJINGS. 



135 



AiM 



tlio kernel closely ; somelimos it is expanded into a wiiuj, as in tlio 

 Trumpet-Creeper (Fig. 31(5), and o('eiu-;ionally this wing is eut up 

 into shreds or tufts, as in the Cntalpa ; or instead of a 

 wing it may hear u cdihh, ( r tuft of long and soft hairs, 

 such as we find in the ;Milk\\eed or Silkweed (Fig. 317). 

 The ohject of wings or downy tufts is to render the seeds 

 huoyant, so that they may he widely dispersed hy the 

 winds. This is clear, not only from their evident adap- 

 tation to this purj)ose, hut also from tlie interesting fact 

 tliat winged and tufted seeds are Ibuiul only in fruits that split open 

 at maturity, never in those that remain closed. The coat of some 

 seeds is heset with long hairs or wool. Cdffon, one- of /('ijijji. 

 tiie most important vegetal)le ])roducts, — 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. Certain 

 seeds have an additional, hut more or less incomplete 

 covering, outside of the real seed-coats, called an 



370. Aril, or Arillus. Tlie loose and transparent hag 

 which encloses tlie seed of the "White Water-Lily (Fig, 

 318) is of this kind. So is the mace of the nutmeg; and also the 

 scarlet pulp around the seeds of the Waxwork (Celastrus) 

 and Strawherry-husii (Euonymus), so ornamental in autunui, 



Ql after the pods burst, Tlie aril is a growth from the ex- 

 j tremity of the seed-stalk, or the placenta. 

 / 371. The names of tin,' parts of the seed and of its kinds 

 c the same Jis in the 

 stalk separates is called ^ . 

 the Ililmn. The orifice 

 of the ovule, now closed 

 up, and showing only a 

 small point or mark, is 

 named the Micropylc. The term 



orthotropous, ondtrapous, &c. 



Fl<;. 311". A wingpd sped of the Tnimpct-Croeper. 



FIC. 317. Seed of Milkwppd, willi a coma or tiil't of loiip silky liaiM at oiio i-iid. 



FK;. 318. Seed of U'liito Water- MIy, emli.scd in its aril. 



FIti. 3iy. Seed of a Vinlet (niiatrn|MiiiK) : a, liiliiiii ; h, rliaphr ; r, rlialn/.a. 



FIG. 32). Seed of a Larkspur (also niialro|Mms) j llio parts lilierrd as i:i the las'. 



FIG. 321. T'ho same, riit IhroiiBh lengthwise: o, tlio liiliini ; r, rlialaza ; i/, outer seed- 

 coal ; r, inner seed-coit ; /, the albiinion ; ;f, the nilniKe einhryo. 



FIG. a*}. Seed of a St. Joliirs-wort, divided luii(,'lli\viso ; hero llio whole kernel U 

 embryo. 



