554 



ON SEEDLINGS 



become large and woody, thickened at the end, densely imbricating 

 and each containing at the base of the inner face two large winged 

 seeds resembling samaras. Scales persistent, ultimately separating 

 to allow the seeds to drop out. 



Seed obovoid, dorso-ventrally compressed and winged at the top ; 

 after removal of this wing the margins are seen to be drawn out into 

 two thin edges, or incipient wings ; seed-coat after removal of the 

 wing consisting of two layers, the outer one of which is thick, hard, 

 and woody, comprising a thin outer dark brown or black stratum, 

 and a pale brown, much thicker inner stratum ; the inner layer 

 is pale brown and black at the radical end of the seed, thin and 

 membranous, but capable of being broken or split up into two thinner 

 strata ; micropyle inferior ; chalaza superior. 



Endosperm copious, white, subfarinaceous, surrounding the 

 embryo. 



Embryo central, large, straight, nearly equal in length to the 

 endosperm, colourless ; cotyledons six to seven, packed together hi a 

 clavate mass, linear- oblong, obtuse, trigonous, several times shorter 

 than the radicle; radicle and hypocotyl 

 together stout, cylindrical, abutting 

 against the remains of the suspensors 

 at the base of the seed and close to the 

 micropyle. 



Pinus rigida, Mill. (fig. 678). 

 Primary root tapering downwards, 

 subflexuose, unbranched for some time 

 after germination. 



Hypocotyl erect, terete, glabrous, 

 deep glaucous-green, and more or less 

 stained with red near the base, 8-18 mm. 

 above the soil. 



Cotyledons four to six, acicular, ob- 

 tusely trigonous, attenuately acute and 

 slender at the tip, glaucous-green, gla- 

 brous, straight in the seed, but during germination pushed out by 

 their own elongation, bulging out all round, and finally pulling 

 themselves out of the seed, after which they gradually spread out 

 to the light, attaining a length of 1-4-1-6 cm. 1 

 Stem erect, woody. 

 Leaves dimorphic, simple, cauline, sessile, exstipulate, glabrous. 



1 Tubeuf , 1. c. p. 86, says : ' The plant has lost its cotyledons by the beginning 

 of the second year.' 



FIG. 678. Pinus rigida> x 2. 



