A fig is really an inside-out bouquet of flowers pollinated by tiny wasps
What we call a fig fruit is a hollow, fleshy stem lined inside with hundreds of minute flowers. The only way in is a tiny hole at the tip, and specialised wasps crawl through it to lay eggs, carrying pollen as they go. Without its partner wasp, a fig tree cannot set seed.
Ficus is a genus of about 850 species of trees, shrubs and vines, the largest in the mulberry family, found throughout the tropics. The range of forms is astonishing: an Indian banyan with its spreading aerial roots can cover more than a hectare, while a New Guinea species never grows beyond a metre. Only two species are farmed to any real extent, the common fig and the sycamore fig. Botanists can spot a Ficus by three features together: milky latex, paired scars on the twigs where stipules fell, and leaves whose lowest side veins meet the midrib at a tight angle.
The enclosed flower head is called a syconium. Male flowers usually cluster near the opening, female flowers cover the inner walls, and each fertilised female flower becomes a tiny one-seeded fruitlet, so a single fig may hold thousands. In some species the sexes are split between trees: female trees have long-styled flowers that stop wasps laying eggs, while male trees carry short-styled flowers where wasp larvae can develop. Seedless cultivated figs, which form without fertilisation, have to be propagated from cuttings or grafts.
The partnership has long been cited as a textbook case of coevolution, and genetic dating shows fig and wasp family trees track each other closely. The one-fig-one-wasp rule is looser than once believed, though: a molecular analysis of 119 fig species found 35 per cent had more than one pollinator species, and hidden wasp species have switched hosts. The dependence has practical consequences. Hawaii has introduced some 60 fig species but only four of their wasps, so only those four figs set viable seed there and can spread.
Figs are keystone plants in tropical forests, feeding fruit bats, gibbons, capuchins and especially birds such as hornbills and fig-parrots, which may live almost entirely on figs when fruit is abundant. Some species also lock away carbon: with help from soil bacteria and fungi, they convert stored calcium oxalate into calcium carbonate, and the related iroko tree can deposit up to a ton of it in the soil over its life.
Source: Ficus
