Palo verde

This article is about the desert plant, for the city in California see Palo Verde, California, and for the power plant in Arizona, see Palo Verde Nuclear Generating Station.

The Palo Verde (pal-oh ver-dee) is a tree found in the Sonoran Desert in the southwestern United States and Northern Mexico. Palo Verde is Spanish for "green pole" or "green stick."

Two species of palo verde commonly occur in the Southwest: the foothill, yellow or littleleaf palo verde (Cercidium microphyllum) and the blue palo verde (Cercidium floridum). The common name is inspired by its characteristic green trunk. "Cercidium" comes from the Greek word, "Kerkidon," a weaver’s comb, and was inspired by the plant's fruit. "Microphyllum" refers to the foothill palo verde’s smaller leaves, and "floridum," to the blue palo verde’s abundant flowers. Both species are highly adapted to live in the hot and dry climate of the region they are found in.

Contents

1 Foothill Palo Verde (Cercidium mucrophyllum) 2 Blue Palo Verde (Cercidium floridum) 3 Facts 4 Places named after the Palo Verde

Foothill Palo Verde (Cercidium mucrophyllum)

A Foothill Palo Verde is a bristling, upright-branching tree, mostly found on slopes, and is one of the most common trees of the Sonoran Desert. The species is slow-growing, sometimes living for several hundred years. They typically grow to heights of around 15 feet, although rarely they can reach 20 to 25 feet. Its leaves are yellowish green, and during extensively dry and hot periods the tree will shed them.

The flowers of the palo verde, found on the end of a branch, are small, pale yellow and flower in late spring. The tree may not flower every year, depending on the amount rainfall. If there is enough rainfall, seeds will also appear in 4-8 cm long, soft pods which dip in between each seed. They ripen in July, and stick to the branches. Rodents will often carry and store the seeds underground, where some of them will germinate after a rainy season. The seedlings are very sensitive to drought for the first two to three months of their lives, and only about 1.6% will survive after germinating.

The Palo Verde has the characteristic of performing photosynthesis in its bark (hence the green color), and this is what allows it to survive after it has shaved its leaves in hotter periods.

Blue Palo Verde (Cercidium floridum)

A Blue Palo Verde appears somewhat more drooping than its cousin. It is found primarily in desert washes as opposed to the foothills, a result of its greater need for water, although a few can be found in the hills. It is a quick growing tree, maturing much faster than a Foothill Palo Verde and it rarely reaches the age of 100. It is also much taller, growing to heights of 30-40 feet. Its leaves are a bluish green (hence its common name) and it also has the ability to shed them in periods of low rainfall.

The flowers of a Blue Palo Verde are bright yellow, pea like blossoms which cover the tree in late spring. The are accompanied by seed pods which are slightly larger and flatter and have harder shells than a Foothill Palo Verde.

Facts

• The Palo Verde is the state tree of Arizona.

• The Seri Indians grind up the seeds for flour, and also made jewlery out of them.

• Irish botanist Thomas Coulter was the first to categorize the plant. He obtained specimens near Hermosillo, Sonora in 1830.

• Buffelgrass , an exotic species of grass native to Africa and first introduced into the Sonoran desert for livestock grazing, spreads very quickly and will often kill a Palo Verde by taking away nearby water, which could pose a serious threat to the tree in the future.

Places named after the Palo Verde

• Palo Verde, California

• Palo Verde Nuclear Generating Station, Arizona