quercus

The bark of Q. alba, white oak or stone oak; formerly used as an astringent. [L. oak]

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Quer·cus 'kwər-kəs n a genus of hardwood often evergreen trees or shrubs (family Fagaceae) that comprise the typical oaks and include sources of nutgall

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Quer·cus (kwurґkəs) [L.] the oaks, a genus of large, leaf-bearing, hardwood trees of the family Fagaceae. Q. alґba (the white oak) and other species make the excrescence called the nutgall (q.v.). Oaks have gallic and tannic acids in their leaves and acorns, making those parts poisonous to livestock.