cars 3 or more in each leaf-scar =ACERACEAE=, p. 70.

19a. Bundle-scar 1 in each leaf-scar 1b, in =LAURACEAE=, p. 41.

19b. Bundle-scars 3 in each leaf-scar --20.

19c. Bundle-scars 5 in each leaf-scar 7a, in =LEGUMINOSAE=, p. 58.

20a. Branches thorny 5a, in =LEGUMINOSAE=, p. 58.

20b. Branches not thorny 3a, in =URTICACEAE=, p. 24.

--21--

21a. Leaves narrow, needle-like or scale-like; trees mostly evergreen
=PINACEAE=, p. 1.

21b. Leaves broader, flat, never needle-like or scale-like, falling in
winter --22.

22a. Leaves compound --23.

22b. Leaves simple --29.

23a. Leaves opposite --24.

23b. Leaves alternate --26.

24a. Leaves palmately compound with 5-7 leaflets
=SAPINDACEAE=, p. 70.

24b. Leaves pinnately compound --25.

25a. Leaflets 3-5 1a, in =ACERACEAE=, p. 70.

25b. Leaflets 7-11 1b, in =OLEACEAE=, p. 88.

26a. Stem or branches thorny 4a, in =LEGUMINOSAE=, p. 58.

26b. Stem or branches not thorny --27.

27a. Leaflets entire 7a, in =LEGUMINOSAE=, p. 58.

27b. Leaflets entire except for a few large glandular teeth near their
base =SIMARUBACEAE=, p. 65.

27c. Leaflets serrate their entire length --28.

28a. Upper leaflets less than 25 mm. wide
4b, in =ROSACEAE=, p. 51.

28b. Upper leaflets more than 25 mm. wide
=JUGLANDACEAE=, p. 21.

29a. Leaves opposite --30.

29b. Leaves alternate --32.

30a. Leaves entire =CORNACEAE=, p. 83.

30b. Leaves toothed or lobed, not entire --31.

31a. Leaves lobed 1b, in =ACERACEAE=, p. 70.

31b. Leaves merely toothed 27b, in =CAPRIFOLIACEAE=, p. 111.

32a. Leaves entire --33.

32b. Leaves toothed --36.

32c. Leaves lobed --47.

33a. Leaves heart-shape 3a, in =LEGUMINOSAE=, p. 58.

33b. Leaves not heart-shape --34.

34a. Twigs and foliage spicy-aromatic 1b, in =LAURACEAE=, p. 41.

34b. Twigs and foliage not aromatic --35.

35a. Pith 5-angled; fru