Ficus subg. Sycidium

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Ficus subg. Sycidium

Description

Trees, tall to small, shrubs, or climbers (or creepers), terrestrial or (hemi-)epiphytic; with intermittent or continuous growth; — The habit varies from up to 30-35 m tall trees (e.g. in F. melinocarpa and F. primaria) to small ones (as in the majority of the species) to shrubs, large to small, sometimes procumbent (as in F. montana and allied species). The species of sect. Palaeomorphe are often hemi-epiphytic. They establish close to the soil, up to some meters. In species that can become medium-sized to tall trees, F. tinctoria and F. virgata the root-system connecting them the soil can become extensive. In the other species, such as F. pisifera and F. sinuata, the hemi-epiphytes are shrubs, mostly connected with a single tap-root to the soil and with ± horizontal growing roots to anchor the shrub to the trunk of the host-tree. These species do often or sometimes exhibit other habits as well: terrestrial shrubs, small trees, scramblers, or climbers.

Most species of the sect. Sycidium show intermittent growth, evident from gradual reduction of length of the internodes towards the apex of a growth unit, shedding of the periderm from the twigs of the (leafless) previous growth unit and (consequently) change in colour, and often also from smaller or larger tufts of subpersistent stipules at the apex of the (present) growth unit. Whether intermittent growth usually is linked to deciduousness is not clear. In sect. Sycidium the leafy twigs are hollow or solid (and then usually with ample pith). The species of sect. Palaeomorphe show continuous growth and the leafy twigs are solid and ± angular to ± compressed. In this section, the periderm usually also flakes off below the leaf-bearing part of the twigs.
internal hairs present or absent. Leaves spirally arranged or distichous, less commonly (sub)opposite (or subverticillate), often ± asymmetric, mostly chartaceous or/to subcoriaceous, mostly ± scabrous above and/or beneath, margin mostly dentate (to denticulate), or sometimes lobate; — The majority of the species have alternate and distichous leaves, in a smaller number of species the leaves are spirally arranged. In both cases they can be (sub)opposite or occasionally subverticillate. In some species, F. opposita and F. cumingii, the leaves are mostly more frequently (sub)opposite than alternate. In some species transitions from the predominant distichous arrangement of the leaves to an arrangement in lax spirals can be found. The lamina is often asymmetric, pronouncedly so or slightly so, and then often only at the base. In sect. Palaeomorphe asymmetry is generally expressed in the fact that one side of the base is decurrent, and thus the two sides of the lamina base attached to the petiole at different distances from its base. The decurrent part can be extended by an auricle (partly) concealing the petiole or also part of the leafy twig, by a lobe (in F. aurita) or a strip of mesophyll along the petiole.

The tertiary venation is basically scalariform, but varies to reticulate in particular in small leaves. The basal lateral veins are mostly distinct in length and/or the angle of departure from the midrib. The lateral veins are often branched.

The margin of the lamina is mostly dentate. In several species (e.g., F. cumingii and F. montana they can be pinnately lobate, in particular when juvenile.
stipules semi-amplexicaul to lateral or amplexicaul, mostly small, caducous or (sub)persistent. — The for the genus characteristic fully amplexicaul stipules, leaving annular scars, are absent in the majority of the species of this subgenus. They are semi-amplexicaul to lateral, and the scars do not meet opposite the petiole. However, in about 19 out of 70 Malesian species the stipules are always fully amplexicaul, but in some of these species (e.g., F. ampelas and F. asperiuscula) the stipules are sometimes semi-amplexicaul, whereas in F. heteropleura both states occur about equally frequent. In most of the species the stipules are small, mostly up to 1 cm.
— The perianth consists of 3-6 tepals, which are usually free, but in some species in the pistillate flowers basally or up to the middle connate. The colour varies from dark red (dark red-brown when dry) to pinkish (pale brown when dry) to white. In some species the colour is consistent, in others it may vary from dark red to whitish. The tepals are mostly glabrous, less commonly minutely hairy at the apices or along the margins, or hairy outside. In species with hairs at the apices of the tepals the apices can be minutely denticulate. In some species (as F. gracillima) the tepals become indurate. The staminate flowers are found near the ostiole, in one or more rows. They mostly contain one stamen, sometimes 2, the anthers are c. 0.5 to c. 1 mm long and elliptic to ovate in outline. In sect. Palaeomorphe they mostly contain a short-styled pistil (which can function as a breeding site for fig wasps) or a more or less reduced one in particular in species with small figs. In sect. Sycidium the pistil is much reduced in size and non-functional. Pistillodes may consist of an ovary part and a style part down to just a minute cylindrical structure representing the stylar part. In pistillate flowers the style is usually glabrous, sometimes hairy.
stamens 1 (or 2), anthers elliptic in outline, not apiculate; Fruits achene, lens-shaped to slightly bean-shaped, smooth or slightly tuberculate or punctate, often (slightly) keeled or drupelets with a whitish sub-tetrahedral to lens-shaped, tuberculate or smooth endocarp body; — In the majority of the species the fruits are achenes, lens-shaped to slightly bean-shaped, clearly to faintly keeled, and smooth, or sometimes slightly tuberculate or finely punctate. They are mostly pale yellow to whitish, but in some species (F. elmeri and F. odorata) red(dish). In some species (F. montana, F. sandanakana, and F. subsidens) the fruits are drupaceous, with a white exocarp and a whitish tuberculate or smooth endocarp body, which is (usually?) released from the exocarp at maturity. It is difficult to recognize these drupaceous fruitlets in dried material due to shrinking of the exocarp. Hence, the distribution of the two types of fruitlets in the subgenus is uncertain, and neither is it clear whether transitions from one type of fruit to the other occur.

Distribution

Africa: present Asia-Temperate: Asia-Tropical:, Borneopresent; Indiapresent; New Guineapresent; Sulawesi (Sulawesipresent) Australasia: Continental Africa: present Madagascar: present Pacific: present Sino-Himalayan region: present from French Polynesia to Micronesia, the Ryukyu Islands, S China and westwards to Madagascar (and adjacent islands) and continental Africa, westwards to Senegal: present
The subgenus occurs in an area ranging from French Polynesia to Micronesia, the Ryukyu Islands, S China and westwards to Madagascar (and adjacent islands) and continental Africa, westwards to Senegal. The subgenus comprises c. 115 species; 70 species are known from Malesia; c. 30 species are found in the Pacific and Australia, nearly 10 in Africa and Madagascar and only five are confined to the Sino-Himalayan region. Ficus exasperata Vahl occurs both in India and continental Africa (and the Arabian Peninsula). The subgenus is with 30 species well-represented in New Guinea, with the majority of the species belonging to sect. Sycidium to which nearly all species of subg. Sycidium in the Pacific and Australia also belong. In Borneo, 26 species are found, the majority belonging to sect. Palaeomorphe. With 23 species Celebes is almost as rich, with species of both sections almost equally represented. Most of the species of sect. Sycidium belong to groups centred in the eastern part of the range of the section, but those of the F. heterophylla-group and F. montana-group are centred in the western part of the range.

Pollination

Two genera of fig wasps are involved in the pollination in subg. Sycidium: Kradibia for species of sect. Sycidium and Liporrhopalum for species of sect. Palaeomorphe, but with a few exceptions in which pollinators associated with other subgenera of Ficus are recorded (Wiebes 1994: 116-146).

Citation

Sata - in Contr. Hort. Inst. Taihoku Imp. Univ. 1944: 252
King - in Sp. Ficus. 1888: 73
Gasp. - in Rendiconti Reale Accad. Sci. Fis. 1845: 85
Gasp. - in Ann. Sci. Nat. Bot. 1845: 347
L. - in Fl. Ind. Bat. 1859: 297
L. - in Ann. Mus. Bot. Lugd.-Bat. 1867: 291