One thing to note for the New World orchids (like Oncidium and Cattleya) - most of them originate from areas with some elevation, and therefore significant diurnal temperature variation, even right on the equator where there isn't much seasonal change. There is not nearly the richness of species at the lower elevations that don't get much variation. Certainly there are some - of the Catts, C. violacea comes to mind as one that does come from a tropical area with warm nights. But not that many others, compared to the number of species in Central and South America that grow in mountains or foothills. The same is true of other genera.
That being said, there are some species with widely varied populations, that may behave differently depending on where they actually came from. Example: I saw lots of Epi. nocturnum on the Rio Negro in Brazil, Amazonian universally warm and muggy. I have a plant of this species, I think was originally collected many years ago in Belize (no idea at what elevation, got it from an elderly hobbyist), that grows and blooms very nicely in my southern California back yard (definitely not Amazonian). I don't know if the individual plant would be able to adapt to the tropical climate or if populations are more distinct in their needs within the same species.
Last edited by Roberta; 09-15-2019 at 05:28 PM..
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