Terete

from WordNet (r) 3.0 (2006)

terete
    adj 1: especially of plant parts; cylindrical and tapering

from The Collaborative International Dictionary of English v.0.48

Terete \Te*rete"\, a. [L. teres, -etis, rounded off, properly,
   rubbed off, fr. terere to rub.]
   Cylindrical and slightly tapering; columnar, as some stems of
   plants.
   [1913 Webster]