36 Transactions of the South African Philosophical Society. 



3. On some points in the morphology of Aizoacece. 



a. The inflorescences .of some species of Mesembrianthemum. 



In a number of species of Mesembrianthemum the flowers are borne 

 singly at the ends of vegetative shoots. This (judging from the 

 illustrations in De Candolle's ' Plantes Grasses ') is, for instance, the 

 case in M. spectabilc, M. felinum, M. longistylum and M. glaucum. 

 The same appears to be the case in M. lateriflorum, only here the 

 flowers appear at the end of short lateral branches bearing 

 only two foliage leaves. In all these species the leaves have a 

 decussate arrangement. In M. brachiatum and other species the 

 leaves are also placed in pairs opposite one another, but the upper- 

 most pair have branches in their axils which, after producing a pair 

 of leaves, end in a flower. Thus a typical dichasium is the result. 

 The two leaves preceding each flower can be considered as prophylls, 

 and further branching often takes place with the same result, and 

 thus the dichasial formation of the inflorescence is continued. 



In some other species, such as M. cordifolium (Plate II, E) 

 M. helianthoides , M> viridiflorum, M. crystallinum and M. angulatum, 

 the inflorescences appear at first sight to be very different from the 

 simple cases just cited, but on careful examination it will easily be 

 found that the formation of their inflorescences is essentially the 

 same. It is certainly so in their youngest stages, except that the 

 corresponding branches are not equally strong from the first, and 

 only later on their behaviour becomes different. 



In M. cordifolium, which I have examined in the live state, there 

 are two equally well-developed branches formed in the axils of the 

 two leaves preceding the terminal flower of a vegetative shoot. 

 Each of these bears two leaves and ends in a flower. In the axil of 

 each of these leaves a bud is formed, but only one of them developes 

 strongly at first, and its axis places itself into the prolongation of its 

 parent axis, throwing the terminal flower (Plate II, E II) aside. Thus 

 a sympodium, or false axis, is formed, and as the favoured side- 

 branches proceed alternately from the right and left side of the 

 relative main axis the inflorescence is, if we only take these branches 

 into consideration, a cicinuus, but it is not quite pure, as the opposite 

 branches also develop later on and produce a flower after forming 

 two leaves, and thus a true dichasium is formed, which, however, 

 through the formation of the sympodium, is obscured. There is no 

 term in the English language to adequately represent this form 

 of inflorescence ; in German it is called a " dichasium mit wickel- 

 tendenz." M. heliantlioides appears to agree in the points just 

 mentioned with M. cordifolium. 



The cases hitherto mentioned will assist us in understanding the 



