Family: Scrophulariaceae
Origin, Description & Uses
Leucophyllum frutescens (Texas ranger) is a drought-tolerant shrub native to southwestern Texas and northern Mexico. It is well known for its attractive silvery-gray foliage and showy, trumpet-shaped purple to lavender flowers that often bloom in response to humidity or rainfall. Because of its resilience to heat, drought, and poor soils, it is widely used as an ornamental landscape plant in arid and urban settings, especially in xeriscaping and low-water-use gardens.
Risks & Threats
In Hawaiʻi, Texas ranger is considered a low-risk species, though it has been observed as potentially naturalizing on Oʻahu and Maui. While it is not currently known to be invasive or widely spreading, its ability to tolerate dry conditions and produce seeds means it could establish in disturbed or dry lowland habitats under the right conditions. Continued monitoring is recommended, particularly in dry coastal or open areas, to ensure it does not expand beyond cultivated plantings. As with all non-native ornamentals, choosing native or known non-invasive alternatives is encouraged when possible.
High Risk Traits:
- Grows in USDA Zones 7–11 (broad climate suitability)
- Native to subtropical regions and introduced outside native range
- Unpalatable to deer (resistant to grazing)
- Tolerates salt spray
- Produces viable seed
- Hybridizes naturally with other Leucophyllum species
- Intentional dispersal by people (landscaping)
- Prolific seed production
- Likely forms a persistent seed bank
Low Risk Traits:
- No evidence of naturalization or weediness
- No spines, thorns, or burrs
- Not allelopathic or parasitic
- No evidence of toxicity to animals or humans
- Not shade tolerant (requires full sun)
- Narrow soil pH requirement (strongly alkaline)
- Slow growing (3–5+ years to mature)
- Propagules not adapted for wind, water, bird, or animal dispersal
- No evidence of vegetative fragmentation
- Susceptible to root rot in humid conditions
