prominent. The leaves come out of the bud conduplicate with slightly involute margins, pale yellow green, downy; when full grown are thin, bright green, rough above, paler green beneath. In autumn they turn to a light yellow. Petioles slender, slightly grooved, hairy. Stipules varying in form, caducous. The flowers are greenish and appear in May, soon after the leaves. They are polygamo-monœcious, meaning that there are three kinds: staminate (male), pistillate (female), perfect (both female and male). They are born on slender drooping pedicels. The calyx is light yellow green, five-lobed, divided nearly to the base; lobes linear, acute, more or less cut at the apex, often tipped with hairs, imbricate in bud. There is no corolla. There are five stamens, which are hypogynous; the filaments are white, smooth, slightly flattened and gradually narrowed from base to apex; in the bud incurved, bringing the anthers face to face, as flower opens they abruptly straighten; anthers extrorse, oblong, two-celled; cells opening longitudinally. The pistil has a two-lobed style and one-celled superior ovary containing solitary ovules. The fruit is a fleshy, oblong drupe, long, tipped with the remnants of style, dark purple when ripe. It is borne on a slender stem and ripens in September and October. It remains on the branches during winter. The endocarp contains significant amounts of biogenic carbonate that is nearly pure aragonite. Distribution and habitat The common hackberry is native to North America from southern Ontario and Quebec, through parts of New England, south to North Carolina-(Appalachia), west to northern Oklahoma, and north to South Dakota. Hackberry's range overlaps with the sugarberry (Celtis laevigata), making it difficult to establish the exact range of either species in the South. Although there is little actual overlap, in the western part of its range the common hackberry is sometimes confused with the smaller netleaf hackberry (Celtis reticulata), which has a similar bark. Hackberry grows in many different habitats, although it prefers bottomlands and soils high in limestone. Its shade tolerance is greatly dependent on conditions. In favorable conditions its seedlings will persist under a closed canopy, but in less favorable conditions it can be considered shade intolerant. Ecology The leaves are eaten by four gall-producing insects of the genus Pachypsylla, which do not cause serious damage to the tree. A number of insects and fungi cause rapid decay of dead branches or roots of the tree. The small berries, hackberries,