Figgy fruit

With a few minutes to spare, which is largely an illusion, so let's say, while wasting a few minutes, TPP stepped into our teaching greenhouse a few short steps from his botany classroom to inhale humid air laden with the smell of luxuriant plant growth.  Especially in the winter this is great therapy.  And there on the floor was a strange, slightly bell-shaped, and for an indoor plant, unusual fruit upon the floor beneath a potted banana (no, clearly not a banana), which was under a Gnetum (which is a gymnosperm, so quite impossible as a fruit producer although it does have a somewhat fleshy seed coat), and so further up was the source.  The entire north end of our glasshouse is home to a quite large fig, the creeping fig, Ficus pumila.  Although rather hard to find and seldom noticed the trunk of this vertically sprawling/climbing fig is about 15 cm in diameter.  And most certainly the fruit was an immature fig syncomium.  This is a tough fruit to understand, and a tough one to explain (TPP has tried before).  OK, lets start with a strawberry.  The fleshy "fruit" is the receptacle (an accessory fruit) and the many pistils of the strawberry flower form fruitlets, little achenes on its surface.  Now if instead of achenes they were drupelets like in raspberries, and if instead of being individual pistils in a single flower they were each a flower, and instead of being bisexual as in the strawberry, the flowers were unisexual, and if the entire thing were then turned inside out, well, simple as that, you'd have a syncomium.  The fleshy outer wall is the receptacle, and on the inner facing wall are unisexual flowers, whitish, male pollen-producing flowers just below the apex (although the syncomium is often pendant) and below them reddish female fruit-producing flowers (Thanks to Gerry Carr for posting this image).  Each fig is pollinated by a species of wasp that requires the fig as a location for mating and rearing its young, and enclosed the way they are, figs also need this particular pollinator, producing an obligate mutualism.  Here's a link to this interaction diagrammed.  Female wasps carrying pollen enter through the apical pore (left) where the inward orientation of bracts prevents leaving.  The next generation of female wasps require males, who never leave the syncomium (try not to think about this too much when eating your next newton) to chew an exit through the syncomium wall.  See, time well wasted.

Who gives a fig?

Rachael Roscata asks: "So not to go on a tangent and cause a billion questions beginning with "Well what about...", but what about a fig? Is it a fruit?"
Well, the Phactor doesn't have to go out on a limb (?) to answer this. A fig is a real fruit, but a very strange one. Rachel found the Phactor's 3-yr-old blog about whether an artichoke was a fruit or a vegetable, a blog read by over 5,500 people since the software began keeping track of traffic.
A fig is a multiple fruit, and an accessory fruit, one composed of a whole inflorescence of flowers that develop enmass into a single fruit. A fig is a synconia, a bulb-shaped receptacle, a modified stem bearing many flowers on its inner surface, so you never see fig flower unless you cut the whole synconia open. So how do it get pollinated? Tiny wasps live and reproduce inside the synconia. Male figs don't produce fruit but they provide a brood substrate for wasp larvae and pollen, which is carried upon female wasps seeking new synconia in which to lay eggs. The pollinated female flowers produce the edible fruits, each flower resulting in a single seed. Each species of fig has a specific and different species of wasp, an interesting evolutionary dance where each species needs the other for its reproduction. Fig flowers are very small, so the actual flower-fruit would be just one of the sort of stringy units within a fig, but the receptacle also develops into fleshy tissue. As pointed out in the artichoke blog, accessory fruits include fleshy tissues associated with the flower or flowers. But Rachael was pretty perceptive in thinking that a fig was a pretty strange fruit. Well, what about that! Try not to think about what happens to the wasps after pollination, but you know those little crunchy bits? They're seeds.