Scientific: Yucca rupicola (Synonyms: Yucca lutescens, Yucca tortilis)
Common: twisted leaf yucca, Texas yucca
Family: Asparagaceae (subfamily Agavoideae)
Origin: Endemic to the rocky outcroppings of the Edwards Plateau in Texas.
Pronounciation: YUK-ka ru-pi-COO-la
Hardiness zones
Sunset 7-24
USDA 7-11
Landscape Use: Accent, xeriscape filler, Spanish architecture, tropical to subtropical, oasis or mixed landscape design themes, rock gardens.
Form & Character: Spreading and clumping, stiff and alarming yet not dangerous like other agave species, green, almost strangely mesic, coarsely refined.
Growth Habit: Evergreen, mostly herbaceous, perennial monocot subshrub, mostly acaulescent up to 2-feet tall with somewhat greater spread.
Foliage/Texture: Elongated, slender, strap-like medium green leaves, 2.5-feet long by 2- to 3-inches wide, tapering to a sharp tip, somewhat bendable, loosely set on stems and sometimes revolute or twisted; coarse texture.
Flowers & Fruits: Multiple extended slender panicles of cream-colored flowers to 5-feet tall. Twisted leaf yucca is monocarpic meaning the main rosette dies after flowering, but it produces multiple offsets which extend the clump before dying. Fruits are a non-ornamental, 'butt-ugly' capsule.
Seasonal Color: Cream white flowers on slender stalks during late spring.
Temperature: Marginally tolerant of Phoenix summer heat, but very cold tolerant to 0oF.
Light: Full sun in Phoenix, though will tolerate some partial shade.
Soil: Tolerant, grows best in alkaline soil.
Watering: Moderately drought tolerant but looks better with occassional irrigation, especially during summer. Excessive dry soil in full sun can cause leaf yellowing.
Pruning: Remove spent flower and fruiting stalks only.
Propagation: Seed (soak seed in tepid water for 24 hours before sowing to shorten germination period), division of offsets, and root cuttings.
Disease and Pests: Occassionally aphids on developing flower stalks during spring, otherwise none.
Additional comments: This is a good, low-growing and clumping green yucca for oasis landscape design themes in Phoenix. It however struggles a bit in hot, exposed xeric landscape sites. Yucca rupicola hybridizes easily with Yucca pallida resulting in offspring with gray-blue, twisted leaves that has been given the obvious and unremarkable commmon name blue twist yucca.
Taxonomic tidbit: The specific epithet rupicola means "living near rocks".
