Tuesday, June 2, 2015

Tillandsia usneioides Flowering

Tillandsia usneoides was in bloom in the UConn greenhouses the other week. The flowers are minute and greenish and easy to overlook, but do emit a slight sweet smell. "Spanish Moss" is indeed not a moss (nor is it from Spain), but a flowering plant in the pineapple family, the Bromeliaceae.

Greenhouse flowering of T. usneoides is unreliable; looking back, I don't see any records of Spanish Moss in flower at UConn since 2004. Intriguingly, the blooms this spring all seemed to be on the clumps of T. usneoides that I had left outside for a portion of last winter in an impromptu hardiness trial. The plants grow perfectly well, vegetatively, when kept in a tropical greenhouse year round, but it is possible that a cold vernalization period triggers flowering. I can't be sure that cold was responsible, though, since a number of other factors were different with the outdoor Spanish Moss. It spent the entire summer of 2014 outside, which means it received rain water rather than tap water, and probably less water and nutrients overall than the non-flowering greenhouse material. Maybe I'll try keeping some plants refrigerated next winter, and see if a cold period alone encourages blooming.

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