The Plants of Michigan

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.