The Collaborative International Dictionary of English v.0.48:

Quercitrin \Quer"cit*rin\, n. [Cf. F. quercitrin. See
   Quercitron.] (Chem.)
   A glucoside extracted from the bark of the oak (Quercus) as
   a bitter citron-yellow crystalline substance, used as a
   pigment and called quercitron.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quercitron \Quer"cit*ron\, n. [F. quercitron, the name of the
   name of tree; L. quercus an oak + citrus the citron tree.]
   1. The yellow inner bark of the Quercus tinctoria, the
      American black oak, yellow oak, dyer's oak, or quercitron
      oak, a large forest tree growing from Maine to eastern
      Texas.
      [1913 Webster]

   2. Quercitrin, used as a pigment. See Quercitrin.
      [1913 Webster]

WordNet (r) 3.0 (2006):

quercitron
    n 1: a yellow dye made from the bark of the quercitron oak tree
    2: medium to large deciduous timber tree of the eastern United
       States and southeastern Canada having dark outer bark and
       yellow inner bark used for tanning; broad five-lobed leaves
       are bristle-tipped [syn: black oak, yellow oak,
       quercitron, quercitron oak, Quercus velutina]