Lobelia laxiflora aka Mexican Lobelia

Lobelia laxiflora, or Sierra Madre lobelia, belongs to the Campanulaceae family. Its native range runs from southern Arizona through Mexico to Colombia. It grows on slopes and in several kinds of forest. Wild sites range from dry to moist, and open to shaded. Kew places it in the seasonally dry tropical zone.

This perennial has a woody base and spreads through rhizomes. Sources also describe it as a shrub or subshrub. Its arching stems bear long, narrow leaves, which fall seasonally. Garden plants reach about 1.6–3.3 feet [0.5–1 m] tall. Their spread reaches about 3.3–4.9 feet [1–1.5 m]. Wild plants show a wider height range, from 0.7–9.8 feet [0.2–3 m]. Stems may stand upright or rise at an angle. They have few branches or none. Plants take two to five years to reach full size.

The red and yellow flowers form tubes about 0.13 feet [0.04 m] long. Each flower grows alone where an upper leaf meets the stem. Bloom runs from late spring through summer. Hummingbirds pollinate the flowers. The RHS lists this plant for beds and flower borders. It also suits courtyard, coastal, and informal garden settings.

Grow it in full sun or partial shade, with shelter. It prefers deep, fertile soil that stays moist but drains well. Sandy or loamy soil suits it, with neutral to alkaline pH. Its RHS hardiness rating is H3, for mild UK areas. Cold sites need winter protection, as its hardiness is limited. Cover the base with dry mulch for winter. Another option is to lift plants and keep them frost-free under glass. Cut stems back once flowering ends. Take semi-ripe cuttings to raise more plants. Slugs may attack it, and crown rot can occur.

Useful Tropical Plants records no known food uses. It lists folk uses for the roots, leaves, and other parts. These include remedies for stomach pain, coughs, fever, and skin complaints. People also use its latex on wounds and itchy skin. These records describe traditional uses, not proof of safe treatment. The RHS warns that eating this plant harms people and pets. Contact can also irritate skin, so wear gloves when handling it. This warning takes precedence over the database's lack of known hazards.