it an acorn 3a, in =FAGACEAE=, p. 22.

35b. Pith not 5-angled; fruit a berry 1a, in =CORNACEAE=, p. 83.

36a. Leaves oblique at base, i. e., one side of the leaf larger
than the other --37.

36b. Leaves symmetrical, not oblique at base --38.

37a. Leaves heart-shape, about as broad as long =TILIACEAE=, p. 72.

37b. Leaves oval or ovate, much longer than wide
1a, in =URTICACEAE=, p. 23.

38a. Stems thorny 41b, in =ROSACEAE=, p. 54.

38b. Stems not thorny --39.

39a. Leaves finely toothed, with 3-many teeth per centimeter of margin
--40.

39b. Leaves coarsely toothed, with 1-2 teeth per centimeter of margin
--46.

40a. Petioles laterally compressed 2a, in =SALICACEAE=, p. 19.

40b. Petioles not compressed --41.

41a. Leaves, or many of them, crowded on short spur-like branches --42.

41b. Leaves scattered, not on short spur-like branches --43.

42a. Bark of the trunks separating in thin papery or leathery
sheets =BETULACEAE=, p. 21.

42b. Bark of the trunk not papery or leathery
24b, in =ROSACEAE=, p. 53.

43a. Lateral leaf-veins straight and parallel, and terminating in the
teeth =BETULACEAE=, p. 21.

43b. Lateral veins more or less curved, and not ending in the teeth
--44.

44a. Leaves palmately veined, about as broad as long; juice
somewhat milky 2b, in =URTICACEAE=, p. 23.

44b. Leaves pinnately veined; juice not milky --45.

45a. Willows, with slender leaves and brittle twigs
8a, in =SALICACEAE=, p. 19.

45b. Trees with lanceolate, ovate, or oblong leaves and tough twigs
30, in =ROSACEAE=, p. 54.

45c. Cottonwoods, with broad, heart-shape or rounded leaves
1a, in =SALICACEAE=, p. 19.

46a. Petioles laterally compressed 2a, in =SALICACEAE=, p. 19.

46b. Petioles not compressed; lateral veins straight and parallel,
running directly to the teeth =FAGACEAE=, p. 22.

47a. Stem thorny 41b, in =ROSACEAE=, p. 54.

47b. Stem not thorny --48.

48a. Leaves pa