Peniocereus greggii

For most of the year this is a handful of grey sticks leaning through a creosote bush. Thin, angular, unremarkable, easy to mistake for something dead. Almost nobody can find one who hasn't been shown where it is.

Underground there's a tuber that typically runs five to fifteen pounds, with old plants reported at sixty pounds and more, storing everything the plant needs for what it does once a year.

On one night in late spring or early summer, it opens. A white flower the size of a saucer, on a long tube, with a scent strong enough to carry a hundred yards. It's pollinated by hawkmoths, and by dawn it's collapsed and finished.

The remarkable part is that they synchronize. Plants across a wide area, with no obvious signal between them, will open on the same night — a cue read from temperature and season that nobody has fully explained. Tohono Chul in Tucson maintains a large collection and predicts the date each year; people come out after dark to walk the grounds while they're open. It's one of the few plant events in the country that draws a crowd at night.

Miss it and you wait a year.