206 



ON SEEDLINGS 



crustaceous testa, or velvety or pilose as in the case of 

 Comesperma, and often furnished with an aril at the hilum 

 as in Polygala. They also contain a large or small quantity 

 of endosperm ; but in a few abnormal genera such as Xantho- 

 phyllum, Moutabea, Krameria, and Securidaca, as well as in 

 a few abnormal species of Polygala, there is no endosperm, 

 and the cotyledons are large, thick and fleshy, so as to fill the 

 seed. Intermediate stages are met with in 

 other species of Polygala and other genera 

 where the endosperm is reduced to a thin 

 stratum surrounding the fleshy embryo. The 

 embryo is always axile and straight, with a 

 short superior radicle. The cotyledons in 

 the species of Polygala observed are oblong 

 or oval, auricled at the base ; the embryo 

 nearly equals the endosperm in length and 

 width but not in thickness, as the seed-leaves 

 are flat or nearly so. In exalbuminous seeds 

 the cotyledons become plano-convex and very 

 thick, so as to fill the seed ; they are then 

 more markedly auricled at the base in order 

 to occupy the seed and yet leave space for 

 the radicle. An instance may be seen in a 

 section of the fruit and seed of Krameria. 

 Besides Comesperma above mentioned the 

 following have more or less hairy or pilose 

 seeds, namely, Bredemeyera, Trigoniastrum, 

 and Carpolobia. 



As regards the means of dispersion, the 

 fruits of Securidaca and Trigoniastrum, 

 which are tall, generally climbing shrubs, 

 are samaras; while those of Mundtia are 

 fleshy, edible drupes ; and those of Krameria 

 bear a number of hooked hairs. 

 FIG. i95.-poiy^aia Cotyledons. The yellowish-green colour 

 rarifoiia. Nat. size, of the seed-leaves of Polygala rarifolia would 

 seem to indicate that they are gradually be- 

 coming functionless after germination and tending to be sub- 

 terranean, and to act merely as a storehouse for reserve- 



