Scientific: Ruellia peninsularis
Common: Baja ruellia, desert ruellia
Family: Acanthaceae
Origin: Baja Califonia and Sonora, Mexico
Pronounciation: Ru-EL-lee-a pe-nin-su-LAR-is
Hardiness zones:
Sunset 12-13
USDA 9-10 (arid regions are best)
Landscape Use: Accent, informal hedge, background, oasis and xeric landscapes.
Form & Character: Upright to rounded, looks like Texas sage except for being more wirey and open, arid, recessive.
Growth Habit: Mostly evergreen, woody, broadleaf perennial shrub, moderate growth rate to 5-feet tall (slightly higher with regular irrigation) and an equal spread, can be maintained as 3-feet tall hedge.
Foliage/Texture: One-inch long, green, opposite leaves on bright gray stems, viscid, stems and leaves pubescent when young; medium fine texture.
Flowers & Fruits: Tubular pale purple to violet flowers to 1-inch wide on purple peduncles; fruits inconspicuous.
Seasonal Color: Flowers present during warm times of year, heaviest in spring and again in fall.
Temperature: Hardy to 25oF, sparsely foliated in winter and even defoliates during severe cold snap, but quickly recovers.
Light: Full sun is best. Shaded locations or north building exposures will inhibit flowering and cause abnormally large leaf expansion.
Soil: Tolerant
Watering: Drought tolerant but responds well to supplemental water, especially when young, by increasing growth rate. However, if watered too heavily then foliar iron chlorosis can be expected.
Pruning: Though occasional heading back will increase canopy density, most Baja ruellia in Phoenix urban landscapes end up being sheared along with Leucophyllum by the 'Horticultural clods of Phoenix' (aka 'Hort clods') into cylindrical, functional outdoor table tops or weird-looking, oblong beerkegs.
Propagation: Semi-hardwood cuttings, seed
Disease and Pests: None
Additional comments: Baja ruellia looks spindly without supplemental irrigation. It is a good, less vigorous, landscape substitute for Leucophyllum frutescens var. green cloud.
Taxonomic tidbits: Ruellia peninsularis is a close relative (similar appearance) to Ruellia californica, which grows exclusively in Baja California. Ruellia california is more cold sensitive than Ruellia peninsularis and is this not suited for landscape use in Phoenix.