Semi-desert, foothills. Woodlands, meadows, openings. Spring.
De-Na-Zin/Bisti Wilderness, New Mexico, April 18, 2005.

Leaves of Thermopsis rhombifolia are usually shorter and broader than those of Thermopsis montana and seed pods are strongly curved.  T. rhombifolia grows 6-18 inches tall; T. montanus grows over several feet tall.  But even more important in distinguishing Thermopsis rhombifolia from Thermopsis montana is the habitat:  T. rhombifolia is a dweller of lower altitudes, prairies, and sandy, dry areas.  T. montana grows in more moist meadows and woodlands of the lower mountains.  In the De-Na-Zin/Bisti Wilderness area, T. rhombifolia grows on hot, dry, sandy/gravelly hillsides in large patches.  It blooms early but its erect, dried stems and its leaves are still evident the following year.

In 1814 Thomas Nuttall named this plant Cytisus rhombifolius from a specimen collected by Bradbury.  Nuttall renamed the plant Thermia rhombifolia in his Genera of North American Plants in 1818, and Richardson named it Thermopsis rhombifolia in 1823.

Semi-desert, foothills. Woodlands, meadows, openings. Spring.
De-Na-Zin/Bisti Wilderness, New Mexico, April 18, 2005.

Semi-desert, foothills. Woodlands, meadows, openings. Spring.
De-Na-Zin Wilderness/Bisti, New Mexico, April 18, 2005.

Thermopsis rhombifolia spreads in large colonies from root sprouts.  Notice the tendency for the roots of this species to grow in straight lines, noticeable in this photo but even more noticeable in the picture below.

Semi-desert, foothills. Woodlands, meadows, openings. Spring.
De-Na-Zin Wilderness/Bisti, New Mexico, April 23, 2007.