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Lobelia laxiflora var. angustifolia (Narrow-leaved Mexican Lobelia)
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© Eugenio Padilla, some rights reserved (CC-BY-SA) · iNaturalist

Lobelia laxiflora var. angustifolia angustifolia

Narrow-leaved Mexican Lobelia

Mexico, Central America (Guatemala, Honduras; dry rocky slopes, oak-pine woodlands, volcanic soils; 3000-8000 ft / 900-2400 m)

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At a Glance

HabitUpright
Height24-36 inches (60-90 cm)
Width24-36 inches (60-90 cm)
Maturity2 years

Growing Zones

USDA Hardiness Zones

7 - 10
These zones indicate the coldest temperatures this plant can typically survive.
What's my zone? →
Frost Tolerancehardy

Overview

Lobelia laxiflora var. angustifolia is a semi-evergreen, rhizomatous, sub-shrubby perennial reaching 24–36 inches (60–90 cm) tall with a spread of 24–36 inches (60–90 cm). This Mexican and Central American native spreads by underground rhizomes to form a loose, upright colony. The narrow, linear-lanceolate leaves are 2–4 inches (5–10 cm) long and only 0.2–0.4 inches (5–10 mm) wide—narrower than the species type (var. angustifolia = narrow-leaved). The tubular, two-lipped flowers are 1.5–2 inches (4–5 cm) long, bicolored red and yellow: the upper lip and tube are red to red-orange, the lower lip flares yellow. Flowers are produced in loose, terminal racemes from April through October in mild climates. The foliage and stems exude a milky sap when cut. Growth rate is moderate. Hardy to zone 7.

Native Range

Lobelia laxiflora var. angustifolia is native to Mexico and Central America (Guatemala, Honduras), in dry, rocky, open slopes, oak-pine woodlands, and volcanic soils at 3,000–8,000 feet (900–2,400 m) elevation. Also naturalized in parts of the southwestern United States.

Suggested Uses

Planted in dry borders, Mediterranean-style gardens, hummingbird gardens, and rock gardens at 18–24 inch (45–60 cm) spacing. The bicolored red-and-yellow tubular flowers attract hummingbirds. The long bloom season (April–October in mild climates) fills a sustained color gap. Spreads by rhizomes—may require containment. The milky sap is an irritant. Not hardy below zone 7. Not suitable for wet soils, heavy clay, or positions where spreading is unwanted.

How to Identify

Distinguished from the species type (L. laxiflora var. laxiflora) by the narrower, linear leaves (0.2–0.4 inches versus 0.5–1 inch wide). Distinguished from L. cardinalis (cardinal flower) by the bicolored red-and-yellow (versus solid red) flowers, the narrower leaves, and the shrubby (versus herbaceous) habit. Distinguished from L. tupa by the smaller stature (24–36 inches versus 48–72 inches) and the narrower leaves. The sub-shrubby lobelia with narrow linear leaves and bicolored red-and-yellow tubular flowers is diagnostic.

Appearance

Size & Dimensions

Height2' - 3'
Width/Spread2' - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~22 weeks
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Tubular, two-lipped flowers 1.5–2 inches (4–5 cm) long in loose terminal racemes, bicolored red/red-orange upper lip and yellow lower lip, from April through October in mild climates. Bloom duration is 20–24 weeks in frost-free areas. In colder zones, bloom is concentrated from May through September.

Detailed Descriptions

Flower Description

Bicolored tubular: red to red-orange upper lip and tube, yellow flared lower lip; 1.5-2 inches long

Foliage Description

Medium green, narrow linear-lanceolate 2-4 inches long, 5-10 mm wide; milky sap when cut

Growing Conditions

Sun Requirements

Requires 5-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.5(Neutral)
357912
Soil Types
Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

1-2 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Plant in full sun to partial shade in well-drained, average to dry soil (pH 6.0–7.5). Hardy to zone 7. Tolerates drought once established. Requires well-drained soil—root rot occurs in wet winter conditions. Spreads by rhizomes—may colonize beyond intended boundaries. The milky sap is irritating to skin and eyes. Cut back frost-damaged stems in early spring.

Pruning

Cut back frost-damaged or winter-tattered stems to the base in early spring as new growth emerges from the rhizomes. Deadhead spent flower racemes to encourage continued bloom. Control spread by removing unwanted rhizomatous shoots.

Pruning Schedule

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early spring

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 5 gallons

⚠️ Toxicity Warning

Toxic to pets and humans