524 ON SEEDLINGS 



contains a solitary Brazilian species with angled, albuminous 

 seeds and a straight embryo with flat, foliaceous cotyledons. 



The embryos of species of Eucalyptus coming under my 

 notice are remarkable for the way in which the cotyledons 

 are deflexed and become folded or coiled round the radicle. 

 The latter is straight in E. Globulus (fig. 338), as are the petioles 

 for part of their length, while the upper portion is bent at 

 right angles to reach the base of the cotyledons. The whole 

 length of the seed is occupied by the radicle, the straight 

 portion of the petioles, and the real length of the cotyledons 

 which is not great. The size of the latter and then: lobed ap- 

 pearance is due to their being deflexed and growing in a lateral 

 direction till they reach the base of the seed while their apical 

 edge becomes coiled round the radicle. The middle portion 

 through which the midrib runs cannot coil round the radicle 

 and is therefore short, thus giving rise to the apical sinus. 

 This will be better understood by reference to the seedlings. 

 A closely similar or identical case occurs in E. marginata, 

 a transverse section of which shows the manner of coiling 

 round the radicle. Although the section showing the coil is 

 transverse to the seed, it is really through the longitudinal 

 plane of the cotyledons. E. stellulata (fig. 341) has very 

 much smaller and narrower seeds, and the coiling is therefore 

 less extensive. The radicle is club-shaped, thickest at the 

 point, and central to the cotyledons. 



A very different case is met with in Couroupita guianensis 

 (fig. 347), where the clavate radicle occupies the periphery of 

 the seed, passing entirely round it and girdling the foliaceous, 

 much plaited, or folded and crumpled cotyledons. The seed 

 is large, suborbicular, laterally compressed and oval or elliptic 

 in transverse section. 



Seedlings. The cotyledons in the seedling stage differ 

 greatly according to the size and shape of the seed. Amongst 

 those observed, three types with some remarkable exceptions 

 may be cited ; but there can be little question that if an ex- 

 haustive series of species were examined the number both 

 of types and exceptions would be considerably increased. 

 The simplest type is that represented by Callistemon rigidus 

 (fig. 337), having small, elliptic or subrhomboid cotyledons. 



