Lewis & Short

aescŭlus (not esc-), i, f. [may be connected with edo = to eat, as fagus = beech, φηγός = oak, with φαγεῖν, but the diphthong presents a difficulty; v. Curt. p. 187], the tallest species of oak, the winter or Italian oak (with edible acorns), sacred to Jupiter, Verg. G. 2, 16; 291; ef. Voss. ad h. l.: nec mollior aesculo, Hor. C. 3, 10, 17 al.