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..
Annual or biennial herbs, with 3-foliolate petioled leaves, dentate leaflets, their veins commonly ending in the teeth, and small white or yellow flowers in slender racemes. Calyx-teeth short, nearly equal; standard obovate or oblong; wings oblong; keel obtuse. Stamens diadelphous; anthers all alike. Ovary sessile or stipitate, few-ovuled; style filiform. Pod ovoid or globose, straight, indehiscent or finally 2-valved. Seeds solitary or few. [Greek, Honey-lotus.]
About 20 species, natives of Europe, Africa and Asia. Type species: Trifolium Melilotus officinalis L.
Flowers white; standard a little longer than the wings.
Flowers yellow; standard about equalling the wings.
Erect or ascending, 3°-10° high, branching, glabrous, or the young twigs and leaves finely pubescent. Leaves petioled, rather distant; leaflets oblong or slightly ob-lanceolate, serrate, narrowed at the base, truncate, emarginate or rounded at the apex, 6"-10" long, 2"-5" wide; stipules subulate; racemes numerous, slender, 2'-4' long, often 1-sided; pedicels 1" long or less; flowers white; standard 2"-2 1/2" long, slightly longer than the wings; pod ovoid, slightly reticulated, glabrous, 1 1/2" long.
In waste places, frequent throughout our area and in the Southern States. Adventive or naturalized from Europe, and native also of Asia. White millet. Honey-lotus. Cabul-, tree-, honey- or bokhara-clover. Leaves fragrant in drying, as in other' species of the genus. June-Nov.
Melilotus altissima Thuill. a European species with narrow, nearly entire leaflets, and pubescent pods, has been found on ballast at Atlantic ports.
Trifolium Melilotus officinalis L. Sp. Pl. 765. 1753. Melilotus vulgaris Hill, Brit. Herb. 308. 1756. Melilotus officinalis Lam. Fl. Fr. 2: 594. 1778.
Resembling the preceding species, but the flowers are yellow. Standard about equalling the wings and keel; leaflets oblong, oblanceolate, or oval, serrate, the apex rounded, not truncate; pod about 2" long, with irregularly reticulated veins, often slightly pubescent with appressed hairs.
In waste places, frequent throughout our area and in the southern States. Adventive or naturalized from Europe. Native also of Asia. Summer, blooming later than M. alba, where the two grow together in southern New York. Old English names, balsam-flowers, hart's-clover, king's-clover, king's-crown, heartwort. Plaster-clover.
Melilotus indica (L.) All., introduced on ballast about the seaports, and an abundant weed in the Far West, may be readily distinguished from this by its much smaller yellow flowers and smaller pods.
Ononis rčpens L., an herb of the tribe Trifolieae, with axillary flowers, forming terminal leafy racemes, has been found as a waif in central New York. The genus is distinguished from others of the tribe by its monadelphous stamens.