DIPSACE^E 95 



layer consists of woody or prosencbymatous tissue, and the base is 

 thicker. Above the lamina of the involucel the woody and com- 

 pact tissue thins out and its place is taken by parenchyma, and in 

 the young state very watery-looking tissue. The pericarp is thin 

 and contains but a moderate amount of vascular tissue, and is there- 

 fore easily burst through when decaying by the germinating embryo. 



The radicle emerges at the apex of the fruit, and immediately 

 turns towards the earth, where it comes in contact with the involucel 

 and pushes through one of the thin membranous parts between the 

 ridges. The hypocotyl has an annular thickening at its base by 

 which the fruit is held down when the radicle enters the ground. 

 The hypocotyl then elongates and pulls the cotyledons out of the 

 fruit as shown in the accompanying sketch (fig. 454, D). 



When the cotyledons have spread out to the light about two days 

 after germination, they are oblong or oval, obtuse, entire, narrowed 

 slightly to the base, sessile, glabrous, and light green ; the hypocotyl 

 is glabrous and colourless. 



Ultimately the cotyledons are oval-oblong, obtuse, shortly petio- 

 late, 1*3 cm. long including the petiole, 7 mm. wide. 



Leaves simple, cauline, opposite, exstipulate, petiolate, or the 

 upper sessile, sparingly hairy ; petioles channelled above, dilated, 

 amplexicaul and connate at the base. 



First pair obovate-spathulate, crenate-serrate. 



Second pair similar, but much larger. 



Third pair spathulate-elliptic, obtuse, attenuate at the base, ser- 

 rate. 



Fourth pair elliptic-oblong, coarsely incise-serrate. 



Fifth pair oblong, pinnatipartite ; segments oblanceolate, acute, 

 entire or slightly toothed. 



Sixth and seventh pairs oblong, pinnatipartite ; segments long, 

 linear, acute, entire or sparingly toothed. 



Scabiosa caucasica, M. Bleb. (fig. 455). 



The radicle emerges at the apex of the fruit and, immediately 

 turning towards the earth, penetrates the thin membranous part of 

 the involucel between the thickened ridges directly beneath the 

 thickened rim. The radicle is long and strong, fixing the seedling 

 firmly in the soil. The base of the hypocotyl is thickened as in the 

 other species described, but this thickening seems generally if not 

 always to push through the involucel and is consequently function- 

 less. 



The cotyledons are gradually pulled out of the fruit by the 

 energy of the growing hypocotyl. 



