92 



ON SEEDLINGS 



in its lower and thickened part ; testa membranous ; hilum basal, 



close to the base of the beak of the ovary. 



Endosperm copious, fleshy, 

 white, forming a very thin layer 

 at the edges of the cotyledons, 

 but much thickened at their backs. 

 Embryo large, straight, nearly 

 equal in length to the endosperm, 

 and nearly as wide in the plane 

 of the cotyledons, pale yellow ; 

 cotyledons obovate, or broadly 

 oval, obtuse or rounded at the 

 end, entire, suddenly narrowed 



FIG. 451. Scabiosa palceatina. . * 



Invoiucel, containing fruit, x 3. into the radicle ; radicle short, 

 stout, turbinate, obtuse, lying in 



the conical base of the seed, and in the basal part of the beak of 

 the ovary. 



Germination (fig. 452). 



The involucel of this species is very large, and plays an important 

 part in the economy of the plant. 



The limb is salver-shaped, membranous with numerous radiating 

 nerves running out at the margin and forming a deeply fringed 

 border. Immediately beneath the rim are numerous perforations 

 between the strong ribs. The radicle in germination always emerges 

 through the opening at the apex of the involucel, easily rupturing 

 the thin and membranous pericarp. 



If the involucel with the fruit is placed mouth downward in the 

 earth (an unnatural position), and but lightly buried or lying on 

 the surface of the soil, the whole may be carried up with the coty- 

 ledons. If, on the other hand, the involucel is lying on its side or 

 with its mouth upwards, the radicle proceeds freely a short distance, 

 and then turning downwards makes its exit through one of the 

 openings, and grows to a great depth straight down into the 

 earth. Some seedlings in the course of germination showed a 

 radicle measuring 2-4 cm. in length, seven days from the time 

 of sowing. This conduct of the radicle is of great importance in a 

 country with the dry climate of Syria, where the plant is indigenous, 

 not only in its depth of penetration, but in effectually fixing the 

 involucel, pericarp, ovary and testa of the seed to the earth while 

 the cotyledons emerge and rise up free. 



The cotyledons afterwards become more or less spread out, oblong, 

 petiolate and tapering into the petiole, showing indistinctly on each 



