69a.

Twigs glandular, resinous, aromatic, with staminate catkins at tips; shrubs

Myrica

69b.

Twigs not glandular; mostly trees

70

70a.

Bud tips appressed; pith mostly chambered

Celtis

70b.

Bud tips spreading; pith not chambered

71

71a.

Bud scales in two vertical rows; floral buds distinctly larger and rounder than foliage buds; no catkins

Ulmus

71b.

Bud scales not in two rows; buds fairly uniform in size; catkins often present

72

72a.

Leaf scars in essentially two ranks; staminate catkins present; twigs tasteless or with wintergreen taste

73

72b.

Leaf scars in several ranks; no catkins present; twigs often with bitter almond (cyanide) taste

Prunus

73a.

Lenticels prominent and elongate; numerous short spur shoots on older growth; bark often with wintergreen taste

Betula

73b.

Lenticels not very prominent and elongate; spur shoots rare; no wintergreen flavor

74

74a.

Buds mostly 4-7 mm. long, rounded in cross-section; staminate catkin usually present

Ostrya

74b.

Buds mostly 2-4 mm. long, foru-sided; staminate catkins absent

Carpinus

75a.

Terminal bud present

76

75b.

Terminal bud absent

83

76a.

Juglans

76b.

Pith continuous, not chambered

77

77a.

More than 3 bundle scars

78

77b.

Three bundle scars

79

78a.

Buds usually yellow or brownish; petiole bases not persisting; vines or shrubs

Toxicodendron

78b.

Buds dark red; petiole bases often persisting; trees or shrubs

Pyrus

79a.

Leaf scars nearly semi-circular

80

79b.

Leaf scars narrowly U-shaped or less than 2mm. in diameter

81

80a.

Bud scales finely hairy, lowermost scale facing outward

Populus

80b.

Bud scales smooth; lowermost scales lateral

Prunus

81a.

Internodes very unequal; twigs yellowish-green

Cornus