Monday, April 5, 2010

Buckhorn Cholla

This post features the buckhorn cholla
but it was an interesting struggle to sort out the differences between a buckhorn and a staghorn cholla and then determine whether what I had been seeing were buckhorn or staghorn or both. I ultimately determined that what I had been seeing were buckhorn cholla.
Buckhorn and staghorn cholla are similar to silver cholla, but the stem segments are longer (six inches or more, verses silver cholla where the segments are four inches or less).
The stem tubercles are also a little longer: three times longer than they are wide for buckhorn and staghorn, while the silver cholla tubercles are about twice as long as wide.
The flower colors vary from red, yellow, orange, pink, purple and greenish or brownish, often all in the same local population. The anther-bearing filaments of buckhorn are dark red and the staghorn filaments are yellowish green. The buckhorn flowers tend to be larger than the staghorn flowers. Staghorn cholla is very similar to buckhorn cholla and it can be very difficult to differentiate between them. The easiest way to differentiate them is by their fruit. The staghorn fruit is fleshy, spineless or weakly spined, and persistent for more than a year (one source said it was pale yellow). Therefore, the staghorn cholla is always in fruit when mature. The buckhorn fruit is covered with numerous long spines, is dry, and falls withn a few months of maturity. One source said that staghorn spines are up to 5/8ths of an inch long, number about 7 to 10 per areole and tend to be reddish and spread out in all directions. Buckhorn spines are up to 1 1/2 inches long, number up to 25 spines per aeole and are tan to straw colored. Both buckhorn and staghorn may be tinged with red or purple, but it happens more often to the staghorn. The buckhorn is widespread in the northern Sonoran and Mojave Deserts. Staghorn is restricted to Pinal, Santa Cruz and eastern Pima counties in Arizona and northern Sonora, Mexico. Organ Pipe Cactus National Monument is in western Pima County and so it is more likely that the staghorn cholla is not there, or if there, is more limited. Buckhorn cholla is extremely variable in vegetative characteristics, such as plant height, branching angle, color, number and size of spines and size and shape of tubercles. There are four varieties and almost every mountain range and valley has a different-looking population. In looking at various websites I found lots of differing and conflicting information about buckhorn and staghorn cholla. Ultimately, I used information on the Arizona-Sonora Desert Museum website as the arbiter where information was inconsistent. But even then, that website did not go into the detail of some other website. With a little more knowledge of cactus on my last trip to Organ Pipe, I noticed buckhorn cholla seemingly everywhere. It tends to be less pretty and interesting than other types of cactus. Based on location in Organ Pipe (western Pima County) and the lack of fruit, I determined that all of the above were buckhorn cholla.
Below are several pictures of buckhorn cholla growing deciduous leaves.
The leaves give them a very strange appearance.

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