14 Bews. — Some General Principles of Plant Distribution as 
other end of its area, in Natal, it has K . brevistylis (recorded only for 
Inanda and for Zululand). The Ranunculaceae are a small family in South 
Africa, and to deal with other larger families in the same detail would be 
tedious. If many families are omitted altogether and others are dealt with 
very briefly, it is not because they do not provide equally good examples. 
Cruciferae. 
The genus Heliophila is endefhic in South Africa. It is characterized 
by a pecular embryo, the cotyledons being twice folded transversely. There 
is one species in Rhodesia, two in the Transvaal, four in Natal, and between 
fifty and sixty at the Cape. Excellent examples of our general principles 
may be found among the species concentrated at the Cape, showing that 
they apply to small areas as well as large. Thus Heliophila diffusa is 
marked by Bolus and Wolley-Dod as ‘frequent’ in the Cape Peninsula: 
H. peltaria, ‘ in similar situations but rarer’, we find differs only in having 
shorter pods and two or three seeds instead of four to eight : H. pilosa is 
common all over the south-western region. Several other closely allied 
species, H. gr amine a, H. linearis , H. strict a, H. divaricata , are much rarer. 
Similar relationships are found among the shrubby species. 
Bixaceae. 
The genus Kiggelaria affords one of the best examples of a widespread 
xerophytic light-demanding pioneer shrubby type giving rise to a meso- 
phytic forest tree type or possibly vice versa. Harvey, in the ‘ Flora Capen- 
sis’, allows three species to stand — K.africana and K. ferruginea, both 
xerophytic ; and K . dregeana , the forest type. Sim, in his ‘ Forest Flora ’ (31), 
sinks them all in one, K. africana , but admits that the forms are distinct. 
Such differences of opinion regarding specific rank are, of course, always 
bound to arise. The distribution of the forest forms is widely discontinuous, 
like the forests themselves. 
Polygalaceae . 
Several species of the large genus Polygala illustrate at the present day 
in South Africa the process of breaking up. Polygala oppositifolia is 
common from the Cape to Natal and Delagoa Bay. It is a typical pioneer 
of scrub occurring around the margins of bush. It has given rise to many 
more mesophytic forms. Harvey recognized eight varieties, but most of 
these, as well as others, have been recognized as distinct species by various 
authors. P. myrtifolia is another widespread species, which is very variable 
in its floral characters and leaves. In this case, Harvey recognized four 
varieties, all elevated to the rank of species by other authors. The fact 
that gradations between the distinct varieties can be recognized does not of 
course necessarily force them to fall into one species, for in a type like this 
hybridizing is quite likely. 
P. virgata is also widespread and has five varieties, according to Harvey, 
and in addition a number of allied species, with more restricted distribu- 
