Dermatophyllum secundiflorum aka Texas Mountain Laurel

Dermatophyllum secundiflorum is known as Texas mountain laurel or mescal bean. Its older name is Sophora secundiflora. It belongs to the pea family, Fabaceae. Its native range spans southeastern New Mexico, southern Texas, and Mexico. It grows in dry scrubland and along streams on limestone soils. Near streams, it can form thickets or small groves. Despite its name, it is not the agave used for mezcal.

This slow-growing evergreen forms a shrub or small tree. It often has several trunks and upright branches. Garden plants usually reach 10–15 feet (3–4.6 m) tall. Larger plants can reach 32–33 feet (9.8–10 m). Some remain shrubs only 3 feet (0.9 m) tall. The gray-brown bark cracks and sheds rough, loose strips. Stout, olive-green twigs bear gray fuzz and small, fuzzy buds. The dense green leaves stay on the plant year-round. Each pinnate leaf has seven to nine glossy, leathery leaflets. Their rounded tips may have a small notch. Their lower faces can look silky or silvery.

Violet-blue, pea-shaped flowers open in spring. They hang in racemes among the glossy leaves. North Carolina State describes clusters 0.25–0.58 feet (0.08–0.18 m) long. The strong scent recalls grape-flavored sweets or drinks. Flowers give way to hard, woody pods with surface hairs. Pods narrow between the seeds and stay closed when ripe. Inside, the seeds turn a bright, lacquer-like red. Growers can raise new plants from seed.

Choose full sun, though the plant also accepts light shade. Deep shade does not suit it. Soil must drain well but may stay moist or dry between rains. It accepts clay, loam, sand, and shallow rocky ground. Rocky limestone soil suits it, and it tolerates alkaline soil. Established plants withstand drought and strong heat. Sources place it in USDA zones 7–10. Older plants are hard to move, so plant young container-grown stock. Its evergreen form suits borders, groups, or a single specimen. It can also grow as an espalier. North Carolina State reports no known insect or disease problems.

The seeds are used for necklaces, but they are poisonous. They contain cytisine, an alkaloid with effects like nicotine. Eating them can cause vomiting, diarrhea, delirium, or coma. No edible use is reported. Historical seed remedies do not make this plant safe to use. The wood yields a yellow dye and is hard and heavy.