Syconium (plural ''syconia'') is the type of

inflorescence An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed ...

borne by figs (genus ''

Ficus ''Ficus'' ( or ) is a genus of about 850 species of woody trees, shrubs, vines, epiphytes and hemiepiphytes in the family Moraceae. Collectively known as fig trees or figs, they are native throughout the tropics with a few species extending int ...

''), formed by an enlarged, fleshy, hollow

receptacle Receptacle may refer to: Biology * Receptacle (botany), a plant anatomical part * Seminal receptacle, a sperm storage site in some insects Electrical engineering * Automobile auxiliary power outlet, formerly known as ''cigarette lighter recep ...

with multiple ovaries on the inside surface. In essence, it is really a fleshy stem with a number of flowers, so it is considered both a multiple and accessory fruit.

Etymology

The term ''syconium'' comes from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

word (''sykon''), meaning "fig".

Morphology

The syconium is an urn-shaped receptacle which contains between 50 and 7000 (depending on the species) highly simplified uniovulate flowers or florets on its inner surface. It is closed off from most organisms by the ostiole, fringed by scale-like bracts. Syconia can be

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy i ...

or functionally

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproducti ...

: the former contain female flowers with variable style length and few male flowers, and produce seeds and pollen. The latter have male and female forms in different plants: seed figs contain female flowers with long styles and produce seeds; gall figs contain female flowers with short styles and male flowers and produce pollen. Once pollinated by a

fig wasp Fig wasps are wasps of the superfamily Chalcidoidea which spend their larval stage inside figs. Most are pollinators but others simply feed off the plant. The non-pollinators belong to several groups within the superfamily Chalcidoidea, while ...

, the individual florets inside the syconium develop into achenes or drupes, in which the seeds are enclosed by a layer of

endocarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. A ...

. From this perspective, the fig is an enclosure with tens to thousands of fruits within it.

Development

Formation of the syconium begins with the initial growth of bracts, which curve to form a receptacle. When the outer bracts meet, they form the ostiole by interlock. Syconia may also develop lateral, basal, or peduncular bracts. There is a relationship between the shape of the ostiole and the morphology of the pollinating wasp.

Pollination

The tight ostiolar enclosure at the syconium's apex makes it highly pollinator-specific. When receptive to pollen, the ostiole slightly loosens, allowing the highly specialized wasps to enter through it. The wasps lose their wings in the process, and once inside they pollinate female flowers as they lay their eggs in some ovules, which then form galls. The wasps then die and larvae develop in the galls, while seeds develop in the pollinated flowers. 4–6 weeks after egg laying, the wingless males emerge, mate with the females still in their galls, and cut a tunnel out of the syconium. As the females emerge, they collect pollen from male flowers, which ripen later. After the wasps emerge, chemical changes in the fig follow as the fig develops into 'fruit'.

Evolution

The syconium is thought to have first evolved 83 million years ago in the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Datwyler, S. L. and G. D. Weiblen
"On the origin of the fig: phylogenetic relationships of Moraceae from ndhF sequences"
''American Journal of Botany'', 2004. 91(5): p. 767–777. within an entomophilic clade within

Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 38 genera and over 1100 species. Most are widespread in tropical and subtropical regions, less so in temperate climates; however ...

that includes tribe Castilleae and genus ''Ficus'', as the bracts protecting the inflorescence tightened to form the ostiole. This greatly increased the pollinator specificity of the plant and initiated a long and complex history of

coevolution In biology, coevolution occurs when two or more species reciprocally affect each other's evolution through the process of natural selection. The term sometimes is used for two traits in the same species affecting each other's evolution, as well ...

between figs and their pollinating wasps ( agaonids).

References

{{fruits Fruit morphology