Monographs Details: Ficus
Authority: Berg, Cornelius C. 2001. Moreae, Artocarpeae, and (Moraceae): With introductions to the family and and with additions and corrections to Flora Neotropica Monograph 7. Fl. Neotrop. Monogr. 83: 1-346. (Published by NYBG Press)
Scientific Name:Ficus
Synonyms:Urostigma Gasp., Pharmacosycea
Description:Genus Description - Trees or shrubs, terrestrial or hemiepiphytic and then with anastomosing aerial roots, monoecious, with waxy glandular spots, usually one or two, at the base of the lamina beneath; uncinate hairs lacking. Leaves alternate, in spirals; lamina entire; venation pinnate; margin entire; stipules fully amplexicaul. Inflorescences with the receptacle (syconium) subtended by a whorl of 2 or 3 (basal) bracts, the apical aperture (ostiole) circular with interlocking (ostiolar) bracts; interfloral bracts present. Staminate flowers numerous to several; tepals 2-6, free or connate; stamens 1 or 2; pistillode present or absent. Pistillate flowers numerous, sessile or pedicellate; tepals 2-4, free or connate; styles of different length in the same inflorescence; stigmas (sub)filiform, 2 or 1. Fruit a small achene.

Discussion:Some of the Old World species (of which several have been introduced into the Neotropics and some of them described as neotropical species) deviate from the present description based on the neotropical representatives of the genus. In the Old World the plants can be climbers, often root-climbers; waxy glandular spots can occur in various positions on the lower surface of the lamina, e.g., in axils of lateral veins other than the basal ones and/or in furcations of veins or (also) on the nodes of leafy twigs; the leaves can be distichous, (sub)-opposite or sometimes subverticillate; the stipules can be lateral; the plants are often dioecious, at least functionally "male," with inflorescences containing either staminate flowers and (non-functional) pistillate flowers with short styles or (functional) pistillate flowers with long styles (and neuter flowers); the ostiole can be slit-shaped; interfloral bracts can be lacking, the outer surface of receptacle can bear (lateral) bracts, a distinct whorl of basal bracts can be lacking; the perianth can be almost lacking; the number of stamens can be more than two; and the fruitlets can be distinctly drupaceous.

The genus comprises approx. 750 species, with 500-550 species in Asia to Australasia, 105 in Africa, and approx. 120 in the Neotropics.

The tremendous diversity, not only in vegetative structures, but also in reproductive ones, inflorescences, flowers, and fruits, could warrant recognition of many genera, as has been attempted in the middle of the past century (Gasparrini, 1844, 1845; Miquel, 1847-1848). However, in 1867 Miquel again merged all genera recognized in the single genus Ficus, for which the most recent subdivision has been proposed by Comer (1965). This subdivision needs some remodelling (Berg, 1989a, 1998). In addition to morphological considerations, the classification of the pollinating fig wasps, as proposed by Wiebes (1994), indicates the need to reconsider Comer’s classification. The size and diversity of the genus Ficus creates a situation of inequivalence with the other genera in Moraceae with regard to systematical and phytogeographical comparisons. The situation can be eased by recognition of adequate subdivisions within Ficus, which can be then compared with other moraceous genera. Such subdivisions or natural groups of species have been indicated by Berg (1989a, 1998b).

The most speciose entity comprises ca. 280 monoecious and essentially hemiepiphytic species (placed in subgenus Urostigma in Comer’s classification): about 100 species are neotropical (and are placed in sect. Americana). Another group of monoecious species is essentially terrestrial and comprises about 75 species (including subgenus Pharmacosycea in Comer’s classification); about 20 of these are neotropical (and placed in sect. Pharmacosycea). Whether sect. Pharmacosycea and the Paleotropical sect. Oreosycea (Miquel) Comer are really related and can be kept in a single subgenus is somewhat doubtful (cf. Herre et al., 1996). The remainder of the genus comprises largely (gyno)-dioecious species; only 15 species (of the Sycomorus group) are monoecious. In the group of (gynodioecious species major subdivisions can be recognized: the Ficus group (largely sect. Ficus), with about 60 species of trees or shrubs; the Synoecia group, comprising two groups of root-climbers (known as sect. Kalosyce (Miquel) Comer and sect. Rhizocladus Endlicher), with a total about 80 species; the Sycidium group (comprising sect. Sinosycidium Comer and sect. Sycidium Miquel), with about 100 species of shrubs, trees, and climbers; and the Sycomorus group (including subg. Sycomorus (Gasparrini) Miquel, sect. Adenosperma Comer, sect. Neomorphe King, and sect. Sycocarpus Miquel), with about 150 species of trees and shrubs, many of them cauliflorous or flagelliflorous (geocarpic).

The two neotropical subdivisions of Ficus species show relationships with Paleotropical entities concentrated in the eastern part of the Asian-Australasian region. Distinct connections with the African Ficus flora are lacking. This fact appears to be reflected in the distribution of the genus in the Neotropics. In contrast to the groups (tribes) showing distinct relations with the African moraceous flora, Ficus is more clearly associated with Central America and the northern Andean region than with the South American continent, where two secondary centers can be recognized: eastern Brazil and the Guiana (or Guayana) region.

The tribe (and genus) has a distinct set of characters, setting it clearly apart from the rest of the Moraceae. Most of these traits, if not all, are related to the unique pollination system.

The inflorescence (syconium, fig) has an urceolate receptacle fully enclosing the flowers at anthesis. The flowers are only accessible to the tiny pollinating fig wasps (and some other insects) which manage to get through the ostiole. The ostiole or entrance to the fig cavity is barred by (interlocking) bracts. The pollinators usually lose their wings (and damage their antennae) on their way into the cavity of the syconium, and there they remain encaged.

The styles of the pistillate flowers are different in length (heterostyly). In the groups of monoecious species (to which all neotropical species belong) all figs contain staminate and pistillate flowers, and heterostyly appears to be realized through and during the ontogeny of the syconium. Intermediate style lengths occur and the ovaries of the densely packed pistillate flowers are ranked in different layers. Due to differences in length of the pedicel or also of the length (and shape) of the ovary, the stigmas are arranged in one layer at anthesis and cohere into a synstigmatic layer. This synstigma is apparently an essential requisite for the pollination system (as briefly described in the Introduction). In the groups of dioecious species (all confined to the Old World) part of the trees ("male" ones) bear figs containing staminate flowers and short-styled flowers, whereas other trees ("female" ones) bear figs with only long-styled flowers (and neuter flower in positions where staminate flowers could be expected). At anthesis the ovaries are arranged in a single layer to produce a cohering layer of stigmas. However, the developing fruits may be arranged in more than one layer.

The anthesis of the staminate flowers is delayed until the fruits (seeds) are ripe; this is characteristic for the genus and essential for the pollination system.

Small waxy glandular spots are omnipresent in the genus and are found at various positions on the leaves and in several Old World groups even on the leafy twigs. They are probably biologically important, but their function is unknown. They might play a role in emitting substances for attracting the pollinators at long distance.

The small seeds can remain dormant for a long time. Light is (mostly) needed for germination. The properties of the seeds make them suitable for long-distance dispersal. However, establishment in remote places will be hampered by the need of a population of trees large enough to sustain the pollination system based on a species-specific plant-animal relation.

The general pattern of the phenology of monoecious (thus of all neotropical) species is to flower year-round to provide continuous breeding sites for the pollinators. These tiny insects live for only a few days and have to find inflorescences with pistillate flowers at anthesis to lay their eggs (and carry out pollination) within that short period. Individual trees have different flowering rhythms, often with ± constant intervals in flower production; the flower production is largely simultaneous. Due to this phenological flowering pattern the genus ensures a continous supply of mature syconia, food for many (arboreal) animals in many habitats.

Many Paleotropical species have been introduced in the Neotropics as ornamentals. Most of the introduced species belong to the subgenus Urostigma. Because of the absence of pollinators, introduced species (e.g., as ornamental trees) do not reproduce. However, in several places, e.g., in Bermuda Islands, Cuba, Florida (Ramírez & Montero, 1988; Kaufmann et al., 1991; Nadel et al., 1992), and Rio de Janeiro (de Figueiredo etal., 1992), several species introduced from Asia (e.g., Ficus altissima Blume and/? microcarpa Linnaeus f.) have started to reproduce, as the pollinators have recently arrived (by plane?) and become established in places with sufficiently large stands of these species.

The present state of taxonomic knowledge of the genus allows rather accurate indications of the number of species for the two neotropical sections of the genus. For most species the distribution is reasonably well known. This knowledge has been accumulated by regional studies of the genus such as for the Flora Meso-americana area (Berg, unpubl.) and the Caribbean region (Berg, unpublished) in addition to floristic accounts of Ficus for Costa Rica (Burger, 1977), Trinidad and Tobago (Berg & van Heusden, 1982), the Netherlands Antilles (Berg, 1980), Venezuela (Berg & Simonis, 2000), the Guianas (Berg, 1992), and Brazilian Amazonia (Berg et al., 1986), complemented by studies on the species of Argentina (Vázquez Avila, 1981) and on species of Brazil (Carauta, 1989).

Some considerable taxonomic problems await further study. They are largely related to some species complexes, the most prominent and widespread ones being: the Ficus americana complex, comprising entities provisionally identified as F. americana Aublet, F. andicola Standley, F greiffiana Dugand, F guianensis Desvaux, F. mathewsii (Miquel) Miquel, and# subapiculata (Miquel) Miquel; and the F. citrifolia complex, comprising entities provisionally identified as F amazonica (Miquel) Miquel, F. brittonii Boldingh, F. citrifolia Miller, F dugandii Standley, F eximia Schott, and F. subandina Dugand.