This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Rhamnus cathartica L. Sp. Pl. 193. 1753.
A shrub, 6°-20° high, the twigs often ending in stout thorns. Leaves glabrous, petioled-, broadly ovate or elliptic, 1 1/2'-2 1/2' long, about 1' wide, regularly crenate or crenulate, acute, obtuse or acuminate at the apex, obtuse or acutish at the base, with 3-4 pairs of veins, the upper running nearly to the apex; flowers dioecious, greenish, about 1" wide, clustered in the axils, unfolding a little later than the leaves; petals, stamens and calyx-teeth 4; petals very narrow; drupe globose, black, about 4" in diameter; nutlets 3 or 4, grooved.
In dry soil, escaped from hedges. New England, the Middle States and Ontario. Introduced from Europe and native also of northern Asia. May-June. Hart's-thorn. Rhineberry. Waythorn. Purging buckthorn. The berries yield a dye, and have powerful medicinal properties.
A tall erect shrub, with smooth grayish bark, and unarmed mostly puberulent branches. Leaves short-petioled, 1'-3 1/2'long, 1/2'-1' wide, ovate-lanceolate to oblong-lanceolate, obtusish or acuminate at the apex, acute or obtuse at the base, glabrous or nearly so above, more or less pubescent, especially on the veins beneath, finely serrulate; veins 6-7 pairs; flowers axillary, 1-3 together, greenish, about 1 1/2" broad, appearing with the leaves; pedicels 1"-2" long; petals, stamens and calyx-teeth 4; drupe black, about 3" in diameter, obovoid-globose; stigmas 2; drupe containing 2 grooved nutlets.
In moist soil, Pennsylvania to Iowa and Nebraska, south to Alabama and Texas. May.
Rhamnus alnifolia L'Her. Sert. Angl. 5. 1788.
A small shrub, with puberulent thornless branches. Leaves oval to elliptic, 2-4' long, 1'-2' wide, obtuse to acuminate at the apex, mainly acute at the base, irregularly crenate-serrate; veins 6-7 pairs; petioles 3"-6" long; flowers 5-merous, solitary or 2-3 together in the axils, green, about 1 1/2" broad, mainly dioecious, appearing with the leaves; petals none; fruiting pedicels 3"-4" long; drupe globose, or somewhat obovoid, about 3" in diameter; nutlets 3, grooved.
A tall thornless shrub, or small tree, with puberulent twigs. Leaves elliptic or broadly oblong, glabrous, or somewhat hairy on the veins beneath, 2'-6' long, 1'-2 1/2' wide, acute or acuminate at the apex, obtuse or acute at the base, obscurely serrulate or even entire; veins6-10pairs; petioles 6"-9" long; flowers 5-merous, perfect, greenish, about 1" broad, in axillary peduncled umbels, or some of them solitary, unfolding after the leaves; calyx finely puberulent, or glabrous, campanulate, its lobes lanceolate, acuminate; petals present; drupe globose, sweet, about 4" in diameter; nutlets 3, not grooved.
Rhamnus Frangula L. Sp. Pl. 193. 1753.
A shrub, reaching a maximum height of about 8°, the young twigs finely and sparsely puberulent. Leaves thin, elliptic or obovate, entire or very obscurely crenulate, glabrous on both surfaces, obtuse or cuspidate at the apex, rounded or narrowed at the base, 1 1/2'-2 1/2' long, l'-1 1/2" wide; petioles 2"-4" long; umbels 1-6-flowered, strictly sessile in the axils; flowers 5-merous, perfect; calyx nearly hemispheric, its lobes ovate, acute; fruiting pedicels 2"-5" long; fruit 3"-4" in diameter, the 3 nutlets compressed, not grooved.
In bogs, Long Island, northern New Jersey and Ontario. Naturalized from Europe. May-June. Black-alder. Berry-alder. Arrow-wood. Persian-berry.