The Collaborative International Dictionary of English v.0.48:

Sequoia \Se*quoi"a\, n. [NL. So called by Dr. Endlicher in honor
   of Sequoyah, who invented the Cherokee alphabet.] (Bot.)
   A genus of coniferous trees, consisting of two species,
   Sequoia Washingtoniana, syn. Sequoia gigantea, the "big
   tree" of California, and Sequoia sempervirens, the redwood,
   both of which attain an immense height.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sequoia
    n 1: either of two huge coniferous California trees that reach a
         height of 300 feet; sometimes placed in the Taxodiaceae
         [syn: sequoia, redwood]