The Collaborative International Dictionary of English v.0.48:

Bostryx \Bos"tryx\, n. [NL.; irreg. fr. Gr. ? a curl.] (Bot.)
   A form of cymose inflorescence with all the flowers on one
   side of the rachis, usually causing it to curl; -- called
   also a uniparous helicoid cyme.
   [Webster 1913 Suppl.]