The nectar that isn't for pollinators

Era 11 gives some leaved days a single ant, standing at the base of one leaf. It has nothing to do with /buzz, this site's other insect room — no flower is involved, and nothing gets pollinated. The ant is there for sugar water leaking from a gland that isn't a flower part at all: an extrafloral nectary, a real structure many plants grow directly on a leaf, a leaf stalk, or a stipule, for no purpose but keeping an ant close by. Fava beans have them. So do cherry laurel, passionflower, and cotton, among many others — Bentley's 1977 review in the Annual Review of Ecology and Systematics named the whole arrangement plainly: sugar, traded for bodyguards.

It's an old idea, and for a long time mostly a plausible-sounding one. Rosumek, Silveira, Neves, Barbosa, Diniz, Oki, Pezzini, Fernandes & Cornelissen actually tested it at scale in 2009 (Oecologia 160), pooling 81 separate studies that had each removed ants from some plants and left them on others. Take the ants away and a plant's herbivory damage nearly doubles; the herbivores themselves show up about 50% more often. The effect runs biggest in the tropics, smaller in temperate climates, and biggest of all on plants that depend on one particular ant species rather than whichever one happens by. It isn't a story about a nice-sounding trade; it's a measured one, with the plant's own outcome (leaf area kept, seed set finished) moving with it.

What makes this worth its own room, rather than a line added to /buzz, is that a nectary makes the distinction a flower never quite states out loud: pollination and defense are two different jobs a plant hands to two different kinds of insect, and a plant that wants both has to keep them separate. A flower's own nectar has to be found by something that flies, remembers where flowers are, and moves on to the next one — the whole transaction is built around a visitor leaving. An extrafloral nectary wants the opposite: a visitor that stays, that comes back to the same spot on the same leaf, ideally forever. Ants are good at pollination for almost no plant (their feet and bodies are the wrong shape, and most species barely fly), and that's not a coincidence here — a plant recruiting a stationary guard doesn't want a pollinator's habits at all.

The honest compression, the same kind this file keeps naming for itself: real extrafloral nectaries sit on a specific structure of a specific species (a petiole gland on Vicia faba, a leaf-blade gland on cherry laurel), and a real ant's presence varies hour to hour, weather to weather, colony to colony. This file has none of that texture. One roll decides whether today's specimen grows an ant at all; if it does, the ant always stands at the base of whichever leaf grow() happened to draw first, not a place chosen for any botanical reason — the same "plausible, not exact" placement plant.js already leans on for the bird and the snow it draws elsewhere. One ant, standing for a patrol nobody is actually running.