Along the Path: Our Prickly Neighbors and Their Friends

Opuntia ficus-indica Photo: Judy Herman

By Susan Rothrock Deo

We have some prickly neighbors here in the South Bay, and I don’t mean the people down the street who play loud music at midnight or the kid who “borrows” your soccer ball and “forgets” to return it. I’m talking about the REAL prickly ones: the cacti.  Cacti have figured out how to thrive in warm dry climates like Southern California. Their stems evolved into round or oblong pads that store water and have thick waxy skins. Their leaves evolved into thin, hard pointed thorns, which also provide protection.

Opuntia littoralis. David Ferguson and Joe Shaw, Opuntiads.com

But their most important adaptation, key to their success at water conservation, is keeping their pores closed during the day and opening them at night. This is the opposite of most plants, which open their pores in the daytime. Even though plants need carbon dioxide in the daytime for photosynthesis, they also lose a lot of water through their pores. By opening their pores at night to absorb carbon dioxide, cacti don’t sacrifice as great a loss of their precious water.  

The most common of our cacti is the coastal prickly pear, Opuntia littorales, It has oval shaped pads and yellow flowers. Its edible purplish red fruit is often called a “tuna,” which is the Spanish name for the plant. (The fish called “tuna” in English is “atún” in Spanish.) Another species is Opuntia aurea, which has more rounded pads. Opuntia ellisiana is a spineless version, bred for cattle to eat. One of my favorites is the coastal cholla, Cylindropuntia prolifera. Its cylindrical “arms,” or branches, are covered in sharp spines. They look like dancers to me. We often call it “jumping” cholla because its spines readily detach on contact with your skin or clothing. The fine barbs on their needle-sharp spines are very difficult to pull out.

Nopales, the young pads, can be eaten raw in salads or stir fried (after removing the thorns, of course). The fruit can be eaten raw or made into syrup, jam, candy, and wine. Check out these tuna fruit recipes.

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Cactus wren. Calif. Dept. of Fish and Game

Other animals utilize the cactus also. The cactus wren, Campylorhynchus brunneicapillus, is the largest American wren.

It is threatened in many parts of its range, so we welcome it in our coastal sage scrub habitat. It builds its horizontal, football-shaped nest three to ten feet above the ground, among the thorns of the cactus. At one end is a very narrow opening that only the wrens can squeeze through. Once inside the little tunnel entrance, the nest is big and cozy with its feather lining—and safe from predators with all that thorny armor!  

Cactus wren nest in teddy bear cholla. John Owens

The endangered Pacific pocket mouse, Perognathus longimembris, is also found near the cactus in the coastal sage scrub habitat. This tiny silky gray mouse is four to five inches long from nose to tail tip. It is only found within two and a half miles of the ocean. It has a white belly and furry back feet. It stuffs excess seeds in its fur lined cheek pouches and takes the excess back to its burrow to store for leaner times. It also eats vegetation when available, nibbling on cactus pads occasionally. A burrow under a cactus plant has the added advantage of being hard for a predator to reach.

Pacific pocket mouse. Cheryl Brehme / USGS

The next time you see a cactus, steer clear of those thorns, but also remember its role in the ecosystem. Observe its great adaptations–and maybe some of its animal visitors too.

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