State and national parks reveal our cultural and geological history, how nature formed such wonders as the desert and how man adapted to the harsh climate while traveling through and settling the land.

Humans have lived in this desert for 10,000 years, and the park now draws 2 million visitors annually, mostly to see the spring wildflowers bloom.

Springtime is awash with blooming ocotillo (pronounced o-co-tee-yo), whose spidery, 10-to-15-foot-long branches look dead until rain falls and then they burst with green leaves tipped with red flowers.

Chuparosa, a shrub with a tubular red blossom, flourishes along alluvial fans and attracts hummingbirds, which is the common name for the plant, also known as the "red sucker."

Spanish explorers first entered the area in 1772 and Juan Bautista de Anza blazed the first overland emigrant trail from Mexico through the area two years later.

He brought 240 settlers and 1,000 head of cattle along a trial that passed through San Luis Obispo County and established a settlement in San Francisco.

A hundred years later, travelers joining the gold rush rode the Butterfield Overland Stageline through he desert, stopping every 20 miles or so at one of the park's palm oasis.

Cool, lush, and rocky, the oases remain home to the borrego, the bighorn sheep that survey their surroundings while perched precariously on steep canyon walls.

There are only about 500 known peninsular bighorn sheep, with 300 protected within Anza-Borrego. Borrego is the Spanish word for "lamb" or "yearling ram."

The fantail palm, Washingtonia filifera, is the only native palm in the western continental United States and the largest native palm in North America.

The leaves, or fronds, remain attached to the tree after they die, forming a skirt around the trunk. The fantail has no taproot, relying on a dense, fibrous mat of rootlets to keep competing species from growing in the fantail's living space.

Found in moist canyons, in fractures along fault zones, near seeps and in deep gorges, fantails can grow up to two feet in a year and live for 150 years and the groves can range from single trees to stands of several hundred.

They are primitive trees lingering from Miocene Epoch, a million to 20 million years ago, and once lived over a wide geographic range until the climate became more arid. Now about 100 groves survive in the low desert, including 25 in the park.

More than 80 species of migratory birds use the oases as rest stops while migrating, much like the Indians and stagecoaches did and many of the park's 225 species of birds, 60 reptiles and amphibians, and 60 mammals do today, including coyote and the bighorn sheep.

Indians frequented and lived near the groves, using the sturdy, fibrous fronds to make sandals, baskets, mats and toys and eating the date-like fruit that drop in late summer, after blooming in May through July.

Signs of Indian habitation can found throughout the park. In addition to pictographs, short hikes lead visitors to morteros and metates, rounded depressions and grounding slicks the Indians made in rocks to grind meal from seeds.

Summertime temperatures range from highs in the 100s to lows in the upper 60s and mid 70s. Average yearly rainfall is 6 inches.

Despite the meager rainfall, water (followed by earthquake activity) is the major force shaping the landscape and dictating what plants survive and where.

Flash floods from intense, but short-lived summer cloud bursts, race down steep canyons, carrying huge boulders and tons of mountain debris along alluvial fans and washes.

Plants adapt to life filled with such extremes.

Creosote is the most common shrub in the low desert and may be the oldest.

Radio-carbon dating shows the creosote established itself along the Lower Colorado River more than 17,000 years ago.

Creosote tells a typical tale of adaptability. A resin coats the leaves with a waxy substance that protects the plant from the heat and ultra-violet light, minimizes evaporation to prevent water loss and tastes so terrible that most herbivores are repulsed when they try to eat it.

The park is designed to be enjoyed in various ways. There are hundreds of miles of hiking trails, self-guided nature walks along fault lines and palm canyons, self-guided automobile tours exposing the geology and stagecoach route and dozens of four-wheel drive routes reaching into the backcountry.

One self-guided nature walks visits a herd of elephant trees, a species so rare in the desert that it achieved legendary status until a scientific expedition set off in 1937 to find the tree with folded skin that the Indians used a medicine.

Anza-Borrego has an exceptionally nice visitors' center, built underground in 1979 so it blends into the terrain, in Borrego Springs about 80 miles east of San Diego off State Route 22.

In addition to having nine primitive campsites, with fire rings, pit toilets and picnic tables, the park is one of the very few in the state that allows open camping. You can park and camp almost anywhere.