264 OBSERVATIONS ON PLANTS 



of the order that may be called Brassice^s, but which is 

 much more extensive than the tribe so named by M. De 

 Candolle ; including all the genera at present known with 

 conduplicate cotyledons, as well as some others, in which 

 these parts are differently modified. 



There are tAvo points in the structure of Savignya, that 

 deserve particular notice. I have described the aestivation 

 of the calyx as valvular ; a mode not before remarked in 

 this family, though existing also in Ricotia. In the latter 

 genus, however, the apices of the sepals are perhaps 

 slightly imbricate, which I cannot perceive them to be in 

 Savignya. 



The radicle is described by M. De Candolle as superior 

 wdth relation to the cotyledons. I am not sure that this is 

 the best manner of expressing the fact of its being hori- 

 zontal, or exactly centrifugal, the cotyledons having the 

 same direction. This position of the seed is acquired only 

 after fecundation ; for at an earlier period the foramen of 

 the testa, the point infallibly indicating the place of the 

 future radicle, is ascendent. From the horizontal position 

 of the radicle in this and some other genera, especially 

 Parsetia, we may readily pass to its direction in Biscutella, 

 where I have termed it descendent, a character which I 

 introduced to distinguish that genus from Cremolobus. 

 But in Biscutella the embryo, with reference to its usual 

 direction in the family, is not really inverted, the radicle 

 being still placed above the umbilicus. On the contrary, 

 in CremoIobecB, a natural tribe belonging to South America, 

 and consisting of Cremolobus and Menonvillea, though the 

 embryo at first sidit seems to as^ree in direction with the 

 order generally, both radicle and cotyledons being ascen- 

 dent, it is, in the same sense, not only inverted, but the 

 seed must also be considered as resupinate ; for the 

 radicle is seated below the umbilicus, and also occupies the 

 inner side of the seed, or that next the placenta — peculiari- 

 ties which, taken together, constitute the character of the 

 213] tribe here proposed. It appears to me singular that M. 

 De Candolle, while he describes the embryo of these two 

 genera as having the usual structure of the order, should 



