150 



BRITISH FLOWERING PLANTS 



when ripe, open suddenly with a jerk. In Genista 

 each valve of the pod contains an outer layer of woody 

 cells, so strongly lignified that their internal cavity 



is almost obliterated. 

 The inner layers are 

 less lignified and 

 contract less. In 

 Vicia, Lathyrus, etc., 

 the fibres do not 

 pass straight up the 

 pod, but are crossed, 

 and consequently 

 when the pod bursts 

 it does not, as in 

 the case of Carda- 

 mine, roll up like a 

 watch - spring, but 

 twists itself more or 

 less like a corkscrew 

 (Fig. 88). 



The seeds, as 

 already mentioned, 

 contain no surround- 

 ing albumen, as, for 

 instance, those of 

 Euonymus (see Fig. 

 86), but are entirely 

 occupied by the em- 

 bryo. If any one 

 will examine the 



Fig. S9. —Lathi/rus NissoUa. Seedling. Nat. size „„„J„ ^C „ "Rco-n a 

 «, seed containing the cotyledons. SeCQS 01 a X)ean, d 



Pea, or a Laburnum, 

 for instance, he will find that they fall easily into 

 halves (Fig. 87), the seed-leaves or cotyledons (c c) ; 

 that at one end is the little root or radicle (r) ; while 

 between them is the minute shoot (s) which will develop 

 into the future plant. Every one knows split peas. 

 Who split them ? Nature. The halves are the two 

 cotyledons. One result of the fleshiness of the coty- 



