The lecture, held on 13th July at BCSS Oxford Branch, given by Wolfgang Plein, was a review of the work that he and Helmut Rogozinski, and others, have untaken over the last 5 years on the Mammillarias of series Mammillaria that grow on the north / west coast of Mexico. The presence of some members of the series in the south Baja California shows that Baja was at one time jointed to the main land and that it broke away about 4 million years ago. It is believed that the split, North to South was in fact a main river and the Rio's (rivers) flowed down out of the mountains in to this main river and then down to the sea.
There was many excellent photographs of the plants that they have studied, refound and described, all of which can be found in AfM. Specific plant complexes / groups are to be found in specific river systems. Each plant complex / group is very variable in all aspect of growth, spination, amount of wool, etc. In the case of flowers most groups have both yellow and red flowering plants which grow in different locations, but there is one place where these two colours grow to together, at El Divisadero and plants with orange flowers can also be found there. Plein also showed a slide of a clump of yellow flowering M.canelensis were one flower head in the clump had orange flowers.
The lecture was finished off with pictures of the rediscovered M.xanthina from Durango. Althought Plein has not visited the habitat he believes it to be related to the canelensis/lindsyi/marksiana complex but cannot say how it has come to be so far away from the others.
At the momment the only thing I would disagreed with Plein is were the plant groups have orginated from. Plein believes they have travelled from the low lands UP the river systems. Has an example......This would mean that there would be a common ancestor growing along the coastal low lands from which M.bocensis has evolved from. M.lindsyi would have evolved up the Rio Fuerte also from the common ancestor. M.canelensis has therefore evolved from M.lindsayi up the Rio Chinipas. The plants in what I call the M.craigii complex would therefore have also evolved from M.lindsayi.
I believe that the plant complexes have evolved in the mountains and travelled DOWN the river systems. If this is the case then M. lindsayi could be a hybrid between the M.canelesis group coming down the Rio Chinipas and the M.craigii group in the Barranca del Cobre / Barranca Sinforosa and meeting at the top of the Rio Fuerte. But of course this happened so low ago we might never know for sure but it would be interesting to have this specific group of plants DNA tested to see if we could gain any further information.
It was great to meet Wolfgang Plein and the lecture was excellent. I would certainly recommend the talk should anyone have the oppuortunity to hear it. I would like to thank both Plein for coming over to the UK and the Mammillaria Society for arranging the talk.
Wolfgang plein, Bill Maddams, chairman/Editor, UK Mammilaria Society, Chris43 (Chris Davis), Tam (Mark Masterson)