Thanks to Jean Hengesbaugh for getting this series started.
I first became aware of this phenomenon of weird growths on cactus, when one of the docents at the ASDM sent me a picture of a cholla with such a growth. My first thought was some kind of a gall and in digging around on the internet I couldn't find any mention of a gall that fit this growth. I did find something called Glomerate Saguaros. These resembled to my uneducated eye something similar to the growth on the cholla below.
|Photos by Carole DeAngeli 9/21/2016|
An expert on saguaros (Bill Thornton) got involved in the e-mail thread on this subject and thought this resembled something he called morphologically-aberrant (MA) saguaros and sent me an article he published in the Cactus and Succulent Journal describing them and the possible causes. [The article is a 7Meg pdf file titled "More Weird Saguaros" if anyone is interested in reading further, I'll be glad to forward it.] It really doesn't have an answer to what causes these M-A's, but suggests there might be a link to manganese in the soil. Bill Peachy, another saguaro expert, suggests these growths may start with damage to the plant maybe caused by a mite.
|Close up of growth above|
Meanwhile, Peter Warren, Urban Horticulture Agent with a degree in entomology, took the original growth on the cholla back to his lab for study. He found various insect larvae and some mites. Did any of these creatures cause the growth or did they take advantage of the food and shelter that the growth provided? No one seems to have an answer.
While leading the public lizard walk at Sabino a couple of weeks ago, one of the participants pointed to an odd growth on a Staghorn Cholla along the Bear Canyon Trail and asked what it was? I took a quick picture...
|Photo by Fred Heath 10/10/2015|
... and a closeup more recently.
|Photo by Fred Heath 11/4/2015|
Anne says: Tumors/growths/morphological aberrations in all living things are the result of genetics and/or environment. Regardless of cause, plant growths still look like plants, of course. Even when the code (DNA) gets messed up, it can only get messed up so much. Plants can't grow an eyeball, for example, or hair or scales. As aberrant as it may be, the growth still has to be something the code (DNA) can do.
Stay tuned for more groovy growths in tomorrow's post.