On the Comparative Anatomy of the Genera Ceraria 
and Portulacaria . 1 
BY 
MARGARET RUTHERFORD MICHELL, B.A. 
Queen Victoria Scholar of the University of the Cape of Good Hope. 
With Plate XCVIII and four Figures in the Text. 
HE three species of the genus Ceraria are all typical xerophytes, well 
i- adapted to the dry situations in which the plants grow. The material 
for this investigation was obtained by Dr. Pearson in South-West Africa. 
As both species were found during the flowering season, which does not 
coincide with the period of greatest vegetative activity, some interesting 
points connected with the structure of the stem could not be determined 
with certainty. Ceraria gariepina was found on granite hills in Bushman- 
land, on the same slopes as Pachypodium namaquanum , in January, 1909 
(Text-fig. 1). 
Ceraria namaquensis , material of which was obtained in the Richtersveld 
in January, 1911, had previously been found by Atherston and Wyley in 
undefined localities in Namaqualand. 2 Both these species are small trees, 
averaging about twelve feet in height. Until recently C. namaquensis was 
known as Portulacaria namaquensis , under which name it appears in the 
‘ Flora Capensis \ 3 It has now, on account of important characters of ovary 
and fruit, been placed in a separate genus, Ceraria , 4 of which two other 
species are known, C. gariepina and C. fruticulosa. Portulacaria afra> now 
the only species in the genus, is a large shrub common in the Karroo. 
On account of the close systematic relationship between the two genera 
it was thought that a comparative study of the anatomy might prove 
interesting. The stem of Ceraria is covered with thick leathery bark, 
interrupted at regular intervals by the prominent nodes, each of which 
bears several minute sessile leaves. The plants were only seen during the 
flowering period, when the number of leaves was small. At other seasons 
the leaves are probably more numerous. They are extremely small 
(2-4 mm. in length), obovoid in shape, and extremely fleshy. The branching 
1 Percy Sladen Memorial Expedition in South-West Africa. Report No. 17. 
2 Pearson (’ll), p. 19 1 ( 2 ). 
4 Pearson and Stephens (T 2 ) ( 3 ). 
Sonder, pp. 385-6 ( 7 ). 
[Annals of Botany, Vol. XXVI. No. CIV. October, 1912.] 
