when do bulb flowers form?

Nicholas plummer via pbs pbs@lists.pacificbulbsociety.net
Tue, 30 Jun 2020 13:12:11 PDT
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.

North Carolina, Zone 7

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)
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