Plant Families: Cactaceae

And then there's the Cactus Family (Cactaceae). We're all familiar with it, even if we've never actually walked among cacti in the wild. They are the tall prickly things that grow in cowboy movies, framing coyotes howling at the full moon as it rises in a lavender dusk sky. They scoff at nature's harshest weather, baking in the hot desert sun, and slumbering in the arid chill of night. They are rugged, primitive and exotic. Cacti are survivors.

There are about 140 genera in the Cactus Family, with up to 2,000 species. Most are native to the warm regions of the Americas.

Evolution has served them well for those that grow in hot, dry environments have made obvious adaptations. The cactus's shape reduces surface area, which in turn reduces water loss. Also, they have a shallow root system that allows them to immediately soak up water from brief showers.

Pores in the plant's skin open during the cool nights. This allows for the entry of carbon dioxide, which is then used during photosynthesis in the blaze of the sun.

The spines, which grow from the axils where leaves would normally grow, reflect sunlight and shade the surface, aiding in keeping the plant cool. The spines also discourage animals from eating the plant, and let's face it, in the desert there just isn't much on the menu.

For all this, their simple, spiny, unfriendly appearance, many cacti produce showy flowers. These flowers, which are radially symmetrical, have many separate petals and sepals. The sepals are often petal-like. These may all be fused at the base forming a tube above the ovary. There are also many stamens.

Some tropical species of cactus have small, simple leaves. Most, particularly the desert species, have clusters of spines instead.

The fruit produced by a cactus is usually fleshy, full of seeds, and often edible.

The most widespread cacti in eastern North America are in the Opuntia genus. These include Prickly Pear (O. humifusa), the East Coast Prickly Pear (O. compressa), and Many-spined Opuntia (O. polyacantha). Western North American species include Coastal Cholla (Opuntia prolifera), Grizzly Bear Cactus (O. erinacea), Devils Cholla (O. stanlyi), and Foxtail Cactus (Coryphantha alversonii), to name but a very few.

They are the tall prickly things that grow in cowboy movies, framing coyotes howling at the full moon as it rises in a lavender dusk sky. They scoff at nature's harshest weather, baking in the hot desert sun, and slumbering in the arid chill of night. They are rugged, primitive and exotic. Cacti are survivors. Ya gotta like that about them.

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