The most grateful acknowledgement is given to Prof. Stanley Coulter, Dean, School Science, Purdue University, who has read all of the manuscript and made valuable suggestions, corrections and criticisms.

I wish to acknowledge the assistance of Stella M. Deam, my wife, in field and clerical work.

I wish to thank the Department of Conservation for the opportunity of doing this work.

Key to the Families.

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]

PINÀCEAE. The Pine Family.

Trees and shrubs with a resinous sap, which yields rosin, tar, turpentine and essential oils. The leaves are linear or scale-like, alternate, whorled or clustered; flowers naked, appearing in the spring; fruit a cone or sometimes berry-like. A large family of trees and shrubs, containing over 200 species, found in many parts of the world, and of great economic importance. In Indiana only nine species are native, and the distribution of seven of these species has always been very limited.