90 



ON SEEDLINGS 



Embryo comparatively large, but falling short of the endosperm, 

 straight, axial, yellowish ; cotyledons plano-convex, oblong, obtuse, 

 entire, sessile, lying in the broader plane of the seed ; radicle oblong, 

 obtuse, with a slightly turbinate point, about half as long as the 

 cotyledons, lying close to the upper end of the seed. 



Germination and Seedling (figs. 449, 450). 

 The achene closely occupies the interior of the involucel, so that 

 in germination the radicle gets outside immediately and pushes 

 down straight into the soil for a considerable depth, at the same 

 time giving off numerous root-hairs. 

 There are no perforations below the rim 

 of the involucel, nor are they needed, 

 on account of the shortness of the 

 neck and the small lamina. 



If the involucel is fairly well 

 covered with soil the cotyledons, after 

 the long radicle has established itself, 

 are easily and readily pulled out clear 

 of the seed and its investments. The 

 cotyledons in this species are not very 

 broad, because the seed itself is not 

 very thick. 



The base of the hypocotyl has a 

 thickened projecting ledge which 

 presses against the rim of the involucel 

 and pins it to the earth while the 

 arching upper part grows upwards and 

 extricates the cotyledons (fig. 449, B). 

 About two days after germination 

 the latter become free, and are linear, 

 obtuse, emarginate, and tapering 

 sh'ghtly to the base. 



About four days after germination 

 they are oblong, obtuse, much broader and more distinctly emargi- 

 nate, tapering at the base into a short petiole, with a distinct midrib, 

 and glabrous. 



The cotyledons ultimately become broadly oblong, distinctly 

 emarginate, cuneate at the base, petiolate, trinerved at the base, or 

 for the greater part of their length, and alternately nerved upwards 

 (the venation is best seen on the under surface), glabrous, bright green 

 above, paler beneath ; petiole flattened above, very slightly connate 

 at the base. 



FIG. 449. Scabiosa australis, x 6. 

 Commencement of germination. 



