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STUDIES IN THE CALENDULEAE
475
|ribe have a restricted area of distribution, occupy an isolated
taxono-mical position and appear pronouncedly poor in biotypes. Epibiotic
species primarily occur ön the mountains in S. W. Africa, the Karroo,
the Drakensberg and the Cape proper.
Those of the species of I lie |ribe found in the Namaqua and Karroo
regions are usually möre polymorphous and richer in biotypes than
|bose in the Cape region.
Xorthwards from the South African cenlre the |ribe Calenduleae
shows a vcry strong reduction in the number of ils species. It extends
up iniö the liltoral and montane areas of Angola and iniö Ihe savanna
and light deciduous woods of Ihe Congo and of Northern Rhodesia.
Over the mountains of East Africa the genus Osteospermum stretches
a branch right up to Ihe mountains skirting Ihe Red Sea and Ihe Gulf
of Aden and il is also found in Asia, namely in Ihe Yemen and
Trans-jordania.
In South America llie sole representative of the |ribe is the
1110110-tvpic genus Eriachaenium. It is confined to Ihe subantarctic region of
this continent and occurs only in Southern Chile. The characters of
Eriachaenium dilfer so widely from those of Ihe other genera in the
tribe that it can only be classified tliere with the greatest hesitation.
2. The Connecting Link between the Mediterranean and
South African Centres of the Tribe Calenduleae.
From the Mediterranean and South African centres the laxonomical
units of this tribe greatly diminish in number and frequency in the
direction of the tropical circles, and only a verv few species in the
mountains and highlands of tropical East Africa connect these cenlres
with each other. The niosl important of these are Osteospermum
Vail-lantii, O. monocephahim and Chrysanthemoides monilifera, which may
be designated as connecting species. Of great phvtogeographical interest
is also the bicentric species Osteospermum muricatiim and O. Volkensii,
a species endemic to Kilimanjaro. Up to Ihe present these five
representatives of the tribe are Ihe only ones that have been found in the
tropical belt of East Africa. Further, a few species of this tribe penetrate
into the tropical hell of West Africa as far as southern Angola.
The northernmost species belonging lo the genus Osteospermum
is O. Vaillantii (map fig. 2). Over a distance of c. 1600 km, including
the intervals, it constilutes the sole link between the Mediterranean
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