Encelia farinosa

The plant changes clothes with the weather.

In a wet season brittlebush carries broad green leaves that photosynthesize hard and fast. As the soil dries it replaces them with smaller leaves densely covered in white hairs — the farinosa in the name, meaning floury. Those hairs reflect sunlight and cut water loss, at the cost of blocking some of the light the leaf needs. The plant trades productivity for survival, then trades back when it rains, and it will do this repeatedly in a single year.

The Spanish name is incienso. The stems exude a resin that hardens into amber lumps, and it was burned as incense in the missions of Baja California and Sonora. You can break a stem and smell it.

Brittlebush is a pioneer. It moves onto disturbed ground fast — roadcuts, graded lots, old scrapes — which is why it lines so much of the highway system in central Arizona and why it's often the first thing to green up a construction scar. Stands of it tend to come in strikingly pure.

In March it turns entire hillsides yellow, on flower stalks held well clear of the silver foliage, and then it goes quiet and grey until the next rain.