244 CLN SEEDLINGS 



smooth or pilose or covered with long woolly hairs, as in most 

 of the species of Gossypium. 



In some of the species of the tribe Bombaceae the seed has 

 a fleshy or pulpy aril. Endosperm is present or absent, but 

 is generally scanty and mucilaginous ; it is fleshy and plentiful 

 in a few cases only. 



The embryo varies according to the character of the seed, 

 reniform seeds having a curved and more or less folded embryo 

 with the back of the cotyledons to the axis, and, as the result 

 of the folding, their edges also. In obovoid seeds the embryo 

 is straight as in the subtribe Fremontieae, where the cotyledons 

 are flat. In most cases however the cotyledons are foliaceous, 

 of large size, and folded or twisted and plicate, enclosing the 

 radicle. More rarely they are thick and fleshy as- in Durio 

 zibethinus. 



The radicle in horizontal amphitropous seeds such as those 

 of the Mallow lies in the lower part of the seed, and following 

 the outline of the testa becomes more or less upturned towards 

 the hilum. It is inferior in ascending seeds, and in those that 

 are pendulous it becomes incurved, pointing downwards to the 

 hilum. 



The simplest and most typical form of seed and embryo is 

 that seen in Malva sylvestris or Althaea rosea. The seeds are 

 reniform and the embryo conforms to them in general outline ; 

 the tip being involute and lying between the outer parts. The 

 radicle is more or less wrapped round by the base of the coty- 

 ledons. 



The casebecomes more complicated in Gossypium, where the 

 seed is large and globose or angled. The embryo is short, and 

 in making an effort to attain a large size to fill the seed, which 

 contains but a small quantity of endosperm, the cotyledons 

 have grown excessively in width, and in order to accommodate 

 themselves to the shape of the seed, have become greatly folded 

 and plaited, with their bases wrapped round the radicle. 

 Other instances of large seeds and a complicated embryo may 

 be seen in Bombax, Eriodendron, and Pachira. 



Seeds containing a straight embryo and flat cotyledons 

 have already been mentioned. In those the radicle is very 

 short. 



