Ficus subg. Sycomorus

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Ficus subg. Sycomorus

Description

— The habit ranges from trees of considerable height to shrubs. About 10 species are or can be rheophytic (see Van Steenis 1981). They are adapted to that life-form by growth-form and leaf-characters, but F. macrostyla (Borneo) and F. squamosa Roxb. (Sino-Himalayan region) are also adapted to the rheophytic life-form by the construction of the diaspores which apparently facilitates attachment to the substrate. All species are terrestrial. In many of the species cauliflory and flagelliflory (geocarpy) are conspicuous features of the tree habit. In flagelliflorous species leaf-bearing shoots may arise from the stolons.
Trees or shrubs, with white or yellowish latex, monoecious or (gyno)dioecious. Leaves spirally arranged, (partly) subopposite or (partly) distichous; — The leaves are spirally arranged, (partly) subopposite, or (partly) distichous, at least on ultimate branches. A change from spiral arrangement of the leaves to (sub)opposite and/or subsequent distichous arrangement may take place during the development of the tree.

The leaves are symmetric or, in particular in connection with distichous arrangement, more or less pronouncedly asymmetric. The lamina is often chartaceous and, in conjunction with this texture, the lamina margin often dentate or denticulate, mostly towards the apex of the lamina.
stipules fully amplexicaul. — The inflorescences occur solitary or in pairs in the leaf axils, often in clusters of more than two on short-shoots (spurs) in the leaf axils and often also below the leaves on the older wood or on variously shaped or clustered (branched or unbranched) leafless branchlets on the older wood, knobbly branchlets, more elongate but still stout branchlets, long slender pendulous branchlets on the older wood, down to the trunk, or very long stolon-like branchlets departing from the base of the trunk. Various types of fig bearing branchlets may occur on the same tree or in the same species. Even combinations of axillary and cauliflorous inflorescences in various degrees may occur.

The inflorescences vary considerably in size, from c. 0.3 cm diam. when dry (in F. minahassae) to about 10 cm diam. (in F. dammaropsis). The receptacle often bears lateral bracts, one to numerous, small to large. There are often 5 or more (± distinct) bracts around the ostiole (apical bracts). The number of basal bracts is mostly 3, sometimes there are a few more. They are distinctly verticillate or may be ± scattered.

Interfloral bracts are absent, the staminate flowers are subtended by bracteoles. Internal (or interfloral) bristles are present (often) or absent (less often).

The syconia are often filled with watery fluid during the interfloral phase (and the beginning of the male phase) of the development.

Mature figs are often greenish to yellowish, to yellow-orange, or yellow-brown. Bright colours, as red, are less frequent, sometimes mature figs turn purple to black.
stamens 2 or less often 1, without pistillode. — The achenes are auriculiform to lenticular, with or without a (double) keel, with or without a prominent ‘pseudohilum’ (where the style was attached to the ovary), and with a smooth or more or less tuberculate surface. The features of the fruits are mostly constant or predominant in the sections.
Fruits achenes, smooth or tuberculate and/or keeled, reddish or whitish.

Distribution

Africa: present Asia-Tropical:, New Guineapresent Madagascar: present Malesian region: present Pacific:, Fiji (Fijipresent) Sino-Himalayan region: present Solomon Islands: present from W Africa to N Australia and Fiji: present
The subgenus comprises c. 155 species in an area ranging from W Africa to N Australia and Fiji. Thirty species occur outside the Malesian region, 12 in Africa and Madagascar (and adjacent islands), all members of sect. Sycomorus, 15 in the Solomon Islands and Fiji, and 5 are confined to the Sino-Himalayan region. The subgenus is most speciose and diverse in New Guinea, in particular its eastern part (and the Solomon Islands).

Pollination

The pollinators belong to the genus Ceratosolen in which three subgenera are distinguished (Wiebes 1994).

Subg. Ceratosolen is found in the species of sections Adenosperma, Bosscheria, and Sycomorus, some species of sect. Sycocarpus, and in F. pritchardii, one of the three species of sect. Papuasyce. Subg. Rothropus is found in the majority of the species of sect. Sycocarpus, and subg. Strepitus, is associated with sect. Dammaropsis and found in two other species of sect. Adenosperma and sect. Papuasyce. Some species of Ceratosolen (subg. Ceratosolen) are found in species of subg. Sycidium (F. asperiuscula and F. complexa).

Males of Ceratosolen show (mostly/always?) respiratory adaptations because of the (usual) presence of liquid in the syconia and they (mostly/always?) cut off anthers, which can be found scattered in the syconium (see p. 54).
A. Corner, E.J.H., An introduction to the distribution of Ficus in Reinwardtia 4. 1958, B. Corner, E.J.H., Ficus dammaropsis and the multibracteote species of Ficus sect. Sycocarpus. in Philos. Trans. 281. 1978, C. Corner, E.J.H., Ficus in the Solomon Islands and its bearing on the Post-Jurassic history of Melanesia in Philos. Trans. 253. 1967, D. Corner, E.J.H., Ficus sect. Adenosperma in Philos. Trans. 256. 1969, E. Corner, E.J.H., New species of Streblus and Ficus (Moraceae) in Blumea 18. 1970, F. Corner, E.J.H., Taxonomic notes on Ficus Linn., Asia and Australasia. Addendum II. in Gard. Bull. Singapore 19. 1962, G. Corner, E.J.H., Taxonomic notes on Ficus Linn., Asia and Australasia. III. Subgen. Ficus and sect. Ficus. in Gard. Bull. Singapore 17, H. Corner, E.J.H., Taxonomic notes on Ficus Linn., Asia and Australasia. VI. Subgen. Ficus and sect. Sycocarpus. in Gard. Bull. Singapore 18, I. Van Steenis, C.G.G.J. - in Rheophytes of the world. 1981, J. Weiblen, G.D., Phylogenetic relationships of functionally dioecious Ficus (Moraceae) based on ribosomal DNA sequences and morphology in Amer. J. Bot. 87. 2000, K. Wiebes, J.T. The Indo-Australian Agaoninae (pollinators of figs). in Verh. Ned. Akad. Wet., afd. Natk. 92. 1994

Citation

Gasp. - in Ann. Sci. Nat. Bot. 1845: 348
Corner - in Gard. Bull. Singapore. 1965: 34
Miq. - in London J. Bot. 1848: 109
Gasp. - in Rendiconti Reale Accad. Sci. Fis. 1845: 86
Mildbr. & Burret - in Bot. Jahrb. Syst. 1912: 175
Sata - in Contr. Hort. Inst. Taihoku Imp. Univ. 1944: 179