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STUDIES IN THE CALENDULEAE
483
Fig. 5. Approximate distribution of Dimorphotheca Vaill. ex Much (......) and
Castalis Cass. (— —). Dimorphotheca has an outlier as far north as Angola.
It is the most primitive genus in the tribe as regards the organs of fructification.
The small genus Castalis has a disjunctive distribution.
As I have alreadv poinled ont ön a previous occasion (I p. 23),
Dimorphotheca is the most primitive genus in the tribe in respect of
the evolution of the organs of fructification. In the species that I have
included in Dimorphotheca, the ray flowers as well as the disc flowers
are, in fact, 5-fertile and normativ produce ripe achenes. The ray and
disc achenes are, as indicated by the generic name Dimorphotheca, of
two different types (I p. 47, fig. 2; p. (>7, lig. 4), but |hey naturally
vield similar offspring. The shape and structure of the style in this genus
have alreadv been Ihoroughly discussed in my earlier trealise (I p. 24;
|). 31, fig. 1 a; p. 47, figs. 2 a—c) and Iheir appearance is best illustrated
by the reproductions cited. This genus will probably have comprised
a large number of species and will have had a wide distribution
pre-viously, but it is now reduced lo a few species.
In the remaining species belonging to the tribe Calenduleae either
1. the pistils of the ray florets or 2. the pistils of the disc florets have
undergone a reduction and have become sterile (I p. 25). These reduc-
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