528 ON SEEDLINGS 



cotyledons are plano-convex, and obovate, but in all other 

 respects this species conforms to the type. 



The fruit or acorn of Quercus pedunculata (fig. 669) is 

 oblong, one-celled and one-seeded. The cotyledons are fleshy, 

 oblong, obtuse or slightly emarginate owing to a thickening at 

 the chalaza, and auricled at the base ; but the auricles fit 

 closely to one another, hiding all but the extreme tip of the 

 short radicle. The fruit is surrounded at the base by a scaly, 

 cup-shaped involucre. In the earliest stages it is a three-celled 

 ovary with two ovules in each cell suspended from near the 

 middle of the axial placentas. Soon after fertilisation one 

 ovule develops at the expense of all the others, pushing them 

 aside as well as the placentas, so that at this stage the 

 ovary in either transverse or longitudinal section appears 

 lopsided. The septa become ruptured or destroyed and the 

 placenta-bearing axis gets severed from the apex of the ovary 

 and ceases to lengthen. The ovule in the early stage is 

 pendulous, and anatropous with the hilum a little below 

 the top. As the ovary increases in length and the axial 

 column gets torn from the top, the young seed increases in 

 length much faster above than below its attachment, till in the 

 full-grown state it is practically orthotropous. The chalaza 

 is basal and gives off numerous, strong, branching veins 

 radiating all over the testa up to the micropyle. It is really 

 very close to the hilum owing to the extreme shortness of the 

 raphe (see diagram, fig. 669). The seed is sessile and the 

 axial column really very short and firmly squeezed against 

 the base of the ovary by the seed which completely fills the 

 cavity. 



A fourth type is represented by Castanea vulgaris (the 

 Chestnut) the fruits of which are generally grouped three 

 together within a four-leaved bristly involucre. The ovary 

 consists pf six to nine carpels, uniting to form as many cells 

 with a pair of pendulous anatropous ovules in each cell. It 

 soon becomes one-celled by the rupture of the placentas, and 

 one, rarely two, seeds develop at the expense of the rest. The 

 ovary is densely lined internally with silky hairs. The seed is 

 ovoid or triangular-ovoid according to the pressure brought 

 to bear upon it by others. The cotyledons become concave 



