ARgh, the temperatures came through garbled. Resending to correct that. -------
I stumbled on this paper on cactus germination and propagation http://opuntiads.com/zpdf/cactus-review.pdf while looking for N American Clematis seeds for a Japanese correspondent. It reinforces some statements made recently on this list and undermines others. But it was published way back in 2000. Perhaps every fact in it has been overthrown since then. Cacti are outside my expertise (as is everything else, come to think of it). An extract: ============== ... some observations can be made of the temperature effect on cacti seed germination: (1) Temperature extremes do not favour germination, that is, below 12 degrees C and above 28 degrees C. A temperature of 20 plus or minus 2 degrees C gives a good germination rate in a wide range of genera. (2) Different species have different responses to temperature. (3) Time to complete germination decreases as temperature increases (i.e. Astrophytum myriostigma and Gymnocalycium mihanovichii). (4) Response to temperature depends on seed age (i.e. the optimum temperature for 1 year old seeds is lower than for the 7 year old seeds of Parodia chrysacanthion). (5) Aged seeds take longer to germinate than young ones (e.g. Maihuenia poeppigii). (6) Alternating temperatures give better germination results than constant temperatures. Despite this last statement, alternating temperature effects on cactus seed germination are not very clear ... ===================== Gibberellic acid is mentioned, too, but I won't go there now. Growers of Trillium learn "myrmecochory" early: it means seed distribution by ants. This paper reminds us that myrmecochory is a mere sub-subcategory of zoochory -- seed distribution by animals. If your dog carries a burr, that is epizoochory. If seeds are carried off by a flash flood, that is hydrochory. My new favorite is anemochory -- distribution of seeds by wind. As in anemone, the windflower, yes. Paige _______________________________________________ Alpine-l mailing list [email protected] http://mailman.science.uu.nl/mailman/listinfo/alpine-l
