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..
Amorpha fruticosa L. Sp. Pl. 713. 1753.
A shrub 5°-20° high, with pubescent or glabrous foliage. Leaves thin, petioled, 6'-16' long; leaflets 11-21, distant, short-stalked, oval or elliptic, obtuse and mucronulate, or sometimes slightly emarginate at the apex, rounded or slightly narrowed at the base, 1'-2' long, 5"-10" wide, entire; spike-like racemes dense, clustered or solitary, 3'-6' long; flowers short-pedicelled, 3"-4" long; standard violet-purple, 2-3 times as long as the calyx, emarginate; stamens exserted; pod glabrous, glandular, thick-stalked, 3"-4" long, acute, usually 2-seeded.
Amorpha angustifòlia (Pursh) Boynton, of Texas and Oklahoma, with thick leaflets, acute at both ends, is recorded from Iowa.
Amorpha nana Nutt. Fras. Cat. 1813.
Amorpha microphylla Pursh, Fl. Am. Sept. 466. 1814.
A low bushy shrub, seldom more than 1° high, glabrous or nearly so throughout. Leaves short-petioled, numerous, 1'-3' long; leaflets 13-19, rigid, short-stalked, oval or oblong, rounded or emarginate and mucronate at the apex, obtuse or acute at the base, 3"-6" long, 1 1/2"-2 1/2" wide; spike-like racemes commonly solitary; flowers fragrant; standard purplish, about 2" long; calyx-teeth acuminate; pod short, 1-seeded.
Prairies and plains, Iowa to Minnesota, Manitoba, Kansas and Colorado. May.
Amorpha canescens Pursh, Fl. Am. Sept. 467. 1814.
A bushy shrub, 1°-3° high, densely white-canescent all over. Leaves sessile or very nearly so, numerous, 2'-4' long; leaflets 21-51, approximate, almost sessile, oval or short-lanceolate, obtuse or acutish and mucron-ulate at the apex, rounded or truncate at the base, 4"-7" long, 2"-3" wide, less pubescent above than beneath; spikes usually densely clustered, 2'-7" long; calyx-teeth lanceolate; standard bright blue, nearly orbicular or ob-cordate, about 2" long; pod slightly exceeding the calyx, 1-seeded.
Prairies, Indiana to Minnesota, North Dakota and Manitoba, south to Kansas, Colorado, Louisiana and New Mexico. Named from its leaden-hue, not as indicative of lead. July-Aug.