Quote: >I've seen P besseae growing in Ecuador at ~6000 ft on a northeast-facing >granite cliff with water running continuously down the cliff face. They were >also growing at the base of the cliff in amongst the weeds, grasses & rocks.
I am not even vaguely an expert on this genus. However, for what it is worth the P. besseae that are knownn in Peru (near Tarapoto) grow in seasonal semi-tropical conditions at around 500 m (say, 1500 ft) in tumbled old Andesite and limestone remnants. (This is the decayed East flank of the Andes, where the rock is wearing away.) The habitat is rocky scrubland, rapidly eroding under grazing. I suspect that many species which are seen on cliffs not so much from preference as that they are there because that is the only place that goats and other browsers do not go. The key to the more vertical of the lithophytes - as with alpine plants - is excellent drainage, and the predictability of dry seasons where these are appropriate. Tarapoto does not have a true dry season, but there are wetter periods and dry ones - the Southern hemisphere winter, now - when it does not rain for periods of a week or more. Roads that are now concrete-like become soup in January-March, as anyone attempting the Carretera Marginal at that time of year can attest: Juanjui ate my Toyota. ______________________________ Oliver Sparrow +44 (0)20 7736 9716 www.chforum.org _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
