_Species._ H. Pecan (Marsh.) Britton. Bull. Torr. Club, 15:282. 1888. Pecan, Illinois nut, a large tree, 75 to 170 feet in height and a diameter reaching 6 feet, with rough-broken bark. Young twigs and leaves pubescent, later nearly or quite glabrous; leaflets seven to fifteen, falcate, oblong--lanceolate, sharp-pointed, serrate, green and bright above, lighter below; staminate catkins five to six inches long, sessile or nearly so, sometimes borne near the base on the young shoots but usually from the uppermost lateral buds on last year's shoots; pistillate flowers terminal on shoots of the current season's growth, produced singly or in clusters of two to nine; fruit oblong cylindrical; husk four-valved; nut 3/4 to 2-1/2 inches in greatest diameter, roundish, or cylindrical and pointed, two-celled at the base, partition thin, bitter, seed deliciously sweet. Found native on the moist bottom lands along streams from Indiana south to Kentucky and from Iowa south to Texas, principally along the Mississippi and its tributaries, the Colorado river in Texas, and along some of its tributaries into Mexico. [Illustration: PLATE III. Pecan Flowers. Pistillate enlarged below.] POLLINATION. Since two kinds of flowers are produced on the pecan, one bearing the pistils, the other stamens, the pollen must be transferred from the latter to the former in order that pollination may take place. In many plants the pollen is transferred from one plant or flower to another by means of insects; but in the pecan there are no bright colors, no nectar, no scent to attract insects to carry pollen, but, instead, the wind is the carrying agent and it needs no attractions. Pollen is produced in large quantities, necessarily so, since much of it is wasted. Unfavorable weather conditions at time of blooming may, however, interfere seriously with pollination. Heavy winds or wind-storms, and rains of several days duration, may prevent the necessary and desired distribution of the pollen, as a result of which no fruit is formed. Sometimes the staminate blooms are destroyed by frost while the pistillate ones escape. It makes little difference which is destroyed, however, as in either case the result is the same--no fruit sets. The staminate flowers push out from the lateral buds at the same time the new shoot develops from the terminal one. The pistillate blossom does not appear until the terminal shoot has grown six or eight inches, and in the meantime it is protected by the unfolded leaves. The staminate bloom, on the contrary, is exposed from the first, having no leaves to protect it. In consequence it is much more likely to be cut off by frost. Dr. Trelease refers to several observations on proterandry (maturing of the pollen before the stigmas of the pistils) in the pecan. This, together with the unprotected condition of the staminate blooms, we believe, accounts in a large measure for the non-setting of fruit on the northern boundaries of the pecan area.