If this is Baja California, it's probably just another Mammillaria dioica

by Carol Anne Wujcik

Once upon a simpler time, when a modest number of cacti could be declared and brought across the border from Baja California into the U.S. as baggage, a friend from northern California proudly brought back what he believed was a multi-species collection of Mammillaria. More knowledgeable friends broke the news; he had amassed one of the larger hobbyist collections of Mammillaria dioica.

This species also holds the honour of being the first Mammillaria I ever saw in habitat. I knew it was Mammillaria dioica because the sign on the cactus trail in Anza-Borrego Desert State Park said so. This little Mammillaria was blooming happily in April of 1987. Repeated sightings were common, and I was able to identify it again and again, relatively easy to do when the only other possibility in this area was M.tetrancistra, solitary and more difficult to spot.

In the winter of '90-91 I had the opportunity to drive the length of Baja California with several friends, which afforded me the opportunity of yet more sightings of M.dioica. Each time I would consult Pilbeam's book (easier for aging eyes to read than Hunt), and each time I would wonder if at last I had found -- depending on location -- such species as Mammillaria louisiae, M.arida, or M.phitauiana. I found it difficult to decide if I was looking at another M.dioica, or one of the others.

Still, by default I became the Mammillaria spotter and identifier. Whenever our little group found a Mammillaria they'd demand identification. I took to reading Pilbeam & and also Wiggins (Flora of Baja California) at night by flashlight. So dedicated and fanatical did I become that I compiled lists at night during our one hotel stay. While the others went out to dinner, I stayed in my lonely room listing possible localities. I made maps. I made lists. I learned. I found out there were such things as axillary bristles. I had been innocent of all such knowledge until I realised that if the Mamms weren't flowering co-operatively, I was going to have to differentiate them some other way. Locality might help me narrow the field, but I knew the final identifying was going to be difficult.

I was right. South of Todos Santos, on an isolated beach travel agents dream about, I sat with Pilbeam alternately reading and photographing the setting sun while my companions frolicked thoughtlessly in the waves. Then came the full moon and a hike along the shore watching tiny translucent crabs scuttle out of our way and bury themselves in sand, fleeting forms as difficult to pin down as any Mammillaria identification. But I did have one small victory at this location. Pilbeam's book confirmed the Mammillaria sharing the bluffs overlooking this idyllic beach were Mammillaria (Bartschella) schumannii, the plump little blue bodies growing with Echinocereus sciurus and what I now know as Mammillaria armillata. In other equally beautiful locations they grew alongside M.dioica.

Of the very few other Mamms I was sure I had correctly identified on that trip, the lyrically beautiful Mammillaria capensis from Bahia de los Muertos was my favourite. With spines twisting and turning like a dancer's arms, this was the one cactus I would have brought home if it had been possible.

Once home I did have slides to confirm my trip, and I and the others set about attempting to identify all we had seen. Lured by the promise of refreshments, Woody Minnich of Cactus Data Plants (CDP) Nursery attempted to help us identify the plants in our slides. As often as not, the plant in the transparency wasn't what we thought it had been. If it was a Mammillaria, it was usually found to be M.armillata (easily distinguished -- I was told -- by its distinctively shaped tubercles), or of course, M.dioica. We had seen only a few of the Mammillaria I had attempted to list. With other genera, even with Jatropha, my success was much better.

Someone once said that a true journey has no end, and indeed I continued to be obsessed with trying to identify Baja Mamms. At nurseries, especially C.D.P., I began searching out and requesting Baja Mamms, using my list. As a result, I now have almost two sets of Baja Mamms, most propagations of WM numbers.

As I write this, many are in flower and/or fruit, and a cheerful group they certainly are, especially one large Mammillaria dioica WM551, which flowered last Christmas and kept at it into the summer. This plant is in a communal bowl, giving limited free root room. I hope to plant all these Mamms in this manner, and will try to group plants from similar localities. My mania has gone this far.

Of the Baja Mamms, the most surprising to me is Cochemiea (Mammillaria) halei. I have yet to flower it, but it is a delightfully vertical, straight-spined species, reminding me of a mythical cross between a Haageocereus and a Cochemiea. Most endearing of all, there is no way M.halei can be confused with M.dioica.

As for M.dioica, I now have several individuals, including one which is straight-spined (WM9140). All are floriferous. All will, I hope, live long and flower. Do I now know this plant so well that I will never be fooled again? Not likely. I shall have to look closely...to see whether or not the plant has such characteristics as axillary bristles. Does M.dioica have such bristles? If you don't already know, you will have to look for yourself. I'll never tell.