Robert Dressler (in Phylogeny and Classification of the Orchid Family, 1993) says that there's no sharp distinction between a pseudobulb and a corm, and that the underground pseudobulbs of some orchids can be considered corms. In any case, some orchids produce pseudobulbs that fully mature before flowering (sometimes even flowering on a prior year's pseudobulb when the new pseudobulb is already in growth or almost mature) while others flower off immature pseudobulbs. Bletilla falls in the latter category, and flowering is strongly dependent both on the conditions experienced by the new growth, and the strength of previous years pseudobulbs. Often an orchid won't flower until it has several healthy, mature pseudobulbs in a chain. Dividing into small pieces and drying, as the big bulb vendors seem to prefer, will set back the plant significantly. I have both purple- and white- flowered Bletilla striata clones in my garden. The white flowered plant seems to be less vigorous than the purple flowered forms. It came from a bulb vendor, and like Diane's took several years to reach flowering size after the shock of packaging for sale. If you can find potted plants at a nursery, that is much to be preferred over dry pseudobulbs. Nick North Carolina, Zone 7 https://sweetgumandpines.wordpress.com/ On Tue, Jun 30, 2020 at 3:28 PM Peter Taggart via pbs < pbs@lists.pacificbulbsociety.net> wrote: > This applies to true bulbs. In true bulbs the flower buds formation is > triggered by temperature extremes at between the end of it's growing > season, and the start of the new growing season. > I believe that corms develop their flower buds on the current seasons > growth shoots. > I'm not sure what the position is for pseudobulbs (which is what orchids > have), but this is why plant morphology really can matter. > Peter > (UK) > _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/…