The Tucson Mountain District of Saguaro National Park ranges from 2,180' - 4,687' across desert scrub and desert grassland biotic communities. The Ringtail Trailhead accesses a well-marked trail network through diversely vegetated washes, arroyos and bajadas of the foothills.

Woodpeckers and flickers are the first to excavate saguaros, but many other species will occupy their abandoned nests

Blacktail Jackrabbits can run up to 35 mph over short distances

Because roots obtain water through passive diffusion, succulents can only absorb water from soil that is wetter than their own interiors

Cactus stomates close during the day, virtually sealing the plant from water loss

Many succulents perform a water-efficient form of photosynthesis called CAM (Crassulacean Acid Metabolism)

During droughts, many desert plants will drop their leaves to reduce surface area to water loss

A saguaro’s root system lies just beneath the soil surface and radiates as far as the plant is tall

The Thornscrub ecotone is essentially a wet desert that falls between desert and tropical biomes.

Palo Verde is Spanish for green stick; it's a common nurse plant for young saguaros

CAM photosynthesis may use up to 90% less water than standard C3 photosynthesis

The Tucson Mountain District averages 10-11" of annual rainfall, usually delivered in short, violent bursts

Sky Islands are steep uplifts separated by wide stretches of open dry desert

The spines of most cholla are covered with a papery sheath, which reflect sunlight and limit overheating

Saguaros can grow up to 4,000', but distribution at higher elevations will depend on southern exposure

Like saguaro, cholla roots are very shallow but may extend several meters from the plant just below the surface