| PAGE |
| Leaves linear or scale-like. | PinaceÆ | 19 |
| Leaves not as above. | |
| A. Leaves compound. | |
| Leaves palmately compound. | ÆsculaceÆ | 251 |
| Leaves without an odd leaflet at the end. | CÆsalpinaceÆ | 226 |
| Leaves with an odd leaflet at the end. | |
| Leaves alternate. | |
| Leaflets toothed all around. | JuglandaceÆ | 52 |
| Leaflets entire, or with 1-4 teeth near the base. | |
| Trees with thorns, leaflets entire, generally less than 4 cm. (11/2 inches) long. | FabaceÆ | 233 |
| Trees without thorns, leaflets entire or with 1-4 teeth near the base, generally longer than 4 cm. (11/2 inches). | SimarubaceÆ | 237 |
| Leaves opposite. | |
| Leaflets 3-5, fruit in pairs. | AceraceÆ | 239 |
| Leaflets 5-11, fruit single. | OleaceÆ | 267 |
| A. Leaves simple. | |
| Leaves opposite or whorled. | |
| Petioles more than 4 cm. (11/2 inches) long. | |
| Blades palmately 3-5 lobed. | AceraceÆ | 239 |
| Blades entire or with 1 or 2 lateral lobes. | BignoniaceÆ | 284 |
| Petioles less than 4 cm. (11/2 inches) long. | |
| Flowers 4-parted, stone of fruit round. | CornaceÆ | 259 |
| Flowers 5-parted, stone of fruit flattened. | CaprifoliaceÆ | 288 |
| Leaves alternate. | |
| B. Leaves entire. | |
| Trees with thorns and a milky sap. | Maclura in MoraceÆ | 155 |
| Trees without thorns, sap not milky. | |
| Leaves 3-5 nerved at the base. | |
| Leaves 3-nerved at the base. | Celtis in UlmaceÆ | 146 |
| Leaves 5-nerved at the base. | Cercis in CÆsalpinaceÆ | 227 |
| Leaves with 1 primary nerve. | |
| Leaves usually more than 1.5 dm. (6 inches) long, flowers solitary. | |
| Flowers appearing before or with the leaves. | AnonaceÆ | 161 |
| Flowers appearing after the leaves. | MagnoliaceÆ | 155 |
| Leaves less than 1.5 dm. (6 inches) long, flowers in clusters. | |
| Bark and leaves aromatic. | LauraceÆ | 163 |
| Bark and leaves not aromatic. | |
| Fruit dry, an acorn. | Quercus imbricaria in FagaceÆ | 119 |
| Fruit fleshy. | |
| Fruit with one seed, stone cylindrical. | Nyssa in CornaceÆ | 259 |
| Fruit with more than one seed, rarely one, seeds flat. | EbenaceÆ | 265 |
| B. Leaves finely serrate, coarsely toothed or lobed. | |
| C. Leaves with one primary vein. | |
| Bark and leaves aromatic. | LauraceÆ | 163 |
| Bark and leaves not aromatic. | |
| Staminate and pistillate flowers and fruit in catkins. | |
| Scales of winter buds 2, ovary many-seeded, seeds with a tuft of hairs at the summit. | Salix in SalicaceÆ | 34 |
| Scales of winter buds more than 2, ovary 1-seeded, seeds without a tuft of hairs at the summit. | BetulaceÆ | 78 |
| Staminate and pistillate flowers and fruit not in catkins. | |
| Fruit dry. | |
| Fruit a samara. | Ulmus in UlmaceÆ | 137 |
| Fruit not a samara. | |
| Bark smooth; fruit spiny. | FagaceÆ | 92 |
| Bark furrowed; fruit a smooth capsule. | EricaceÆ | 263 |
| Fruit fleshy. | |
| Flowers more than 8 mm. (1/3 inch) broad, fruit edible, apple-like. | |
| Trees mostly with thorns, fruit with remnant of calyx at apex of fruit, normally with more than 1 seed. | MalaceÆ | 171 |
| Trees without thorns, fruit with no remnant of calyx at the apex, fruit a 1-seeded edible drupe. | AmygdalaceÆ | 216 |
| Flowers less than 8 mm. (1/3 inch) across, fruit a non-edible drupe. | CornaceÆ | 259 |
| C. Leaves with more than 1 primary vein. | |
| Staminate and pistillate flowers in catkins. | |
| Fruit dry. | Populus in SalicaceÆ | 45 |
| Fruit fleshy. | Morus in MoraceÆ | 151 |
| Staminate and pistillate flowers not in catkins. | |
| Pistillate and staminate flowers separate. | |
| Leaves 3-nerved at the base, fruit a 1-seeded drupe. | Celtis in UlmaceÆ | 146 |
| Leaves 5-nerved at the base, fruit a head of carpels or achenes. | |
| Bark fissured, not peeling off in flakes, leaves aromatic. | AltingiaceÆ | 166 |
| Bark peeling off in flakes, leaves not aromatic. | PlatanaceÆ | 168 |
| Pistillate and staminate flowers in one. | |
| Fruit dry. | TiliaceÆ | 255 |
| Fruit fleshy. | MalaceÆ | 171 |
