PLAXTAGIXE^E 393 



and turbinate. The fruit is two-celled and many-seeded. 

 P. maritima differs from the above by having a two-celled, 

 two-seeded fruit, and plano-convex seeds. Endosperm is 

 relatively scanty, and the embryo occupies the greater portion 

 of the seed. In other respects it is similar to P. Coronopus. 



In comparing P. media and P. Coronopus, I find that 

 although the cotyledons of the embryos are differently placed 

 with regard to the placentas, they are most conveniently situ- 

 ated in each case to occupy the greatest amount of the area of the 

 seed and more especially during germination. The cotyledons of 

 P. media are thin, wide and placed in the broad way of the 

 seed so that they can readily grow wider during germination 

 and also utilise the endosperm around them. The cotyledons 

 of P. Coronopus have their edges to the placentas, and their 

 width compared with the combined thickness of the two is as 

 two to three, so that they really occupy a greater area of the 

 seed than if they had their backs to the axis. This is even 

 more evident in P. maritima. 



Seedlings. Just as there are two leading types of seeds, so 

 are there two distinct types of seedlings with their characteristic 

 cot} T ledons. The broad general distinction which I adduce from 

 the seedlings coming under my observation is that species with 

 broad many-ribbed leaves have flat, spathulate or lanceolate, 

 but not necessarily very broad cotyledons ; while those with 

 narrow leaves, whether entire or divided, have linear and thick 

 succulent cotyledons. 



The thin or flat type is represented by Plantago media 

 (fig. 598) which has linear-spathulate or lanceolate cotyledons 

 tipped with a dark spot or minutely emarginate, and one- 

 nerved. One or both cotyledons are liable to fission, so that 

 they may be emarginate, bifid or bipartite, sometimes appear- 

 ing as three or four instead of the normal two. This takes 

 place as a result of growth during germination, and appears 

 to facilitate their exit from the seed. The first leaf is one- 

 nerved ; the second trinerved at the base ; and the third 

 and fourth are trinerved nearly to the apex. All four are 

 spathulate and hairy. The ultimate leaves are ovate and 

 seven- to nine-nerved. P. major belongs to this type. 



The second group is represented by P. Coronopus (fig. 599) 



