Becky, I am not sure there is a correct answer to your question...
I have had some of my cattleyas put up sheathless blooms from time to time.
It was a shocker
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but pleasantly so.
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These same plants have also but up bulbs with empty sheaths
Back in May I moved all my plants to a greenhouse and they happily acclimated to "optimal conditions" and grew like crazy. Thus, I think some of the plants that wanted to flower but couldn't threw some sheathless blooms out etc.
In looking up the geniology of Chia Lin, it is at least 75% cattleya species that do produce sheaths.
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