Scientific: Agave x 'Royal Spine' (Synonym: Agave x 'Green Steel')
Common: Royal spine agave
Family: Asparagaceae (subfamily Agavoideae)
Origin: Hybrid cross of Agave macroacantha and Agave victoria-reginae 'Compacta'
Origin stories: The genesis of this beautiful hybrid is uncertain. One story is that it was reportedly discovered at Tropic World Nursery. Another story is that it came from the famed nursery of Paul Hutchinson in north county San Diego, and another story is that it came from a controlled breeding program at Rancho Soledad Nursery.
Pronounciation: A-GA-ve ROY-al SPINE
Hardiness zones
Sunset 12-24
USDA 9-11
Landscape Use: In Phoenix, this is a wonderful textural accent plant for desert display gardens, rock gardens, raised planters, and smaller oasis and xeric landscape beds where a textural accent plant is desired. This is not an agave for large-scaled xeric or desert landscapes.
Form & Character: Tight, dense, strongly rosetting, stiff, diminuative in stature, dangerous, landscape "eye candy".
Growth Habit: Evergreen, succulent and fibrous, herbaceous perennial, monocarpic, slow growth rate to 18-inches tall and 2- to 3-feet wide (including offshoots), dense basal clumping much like Agave macroacantha.
Foliage/Texture: Stout stiff, strap-shaped, fibrous dull glaucous leaves, 8- to 12-inches long by 2-inches wide, leaves have mostly smooth reddish margins but with occassional very short dark brown teeth, taper to a sharp, stout, darkened reddish brown terminal spine, banding on the abaxial surface of leaves is sometime seen in hot desert climates; medium coarse texture.
Flowers & Fruits: Unknown; likely sterile
Seasonal Color: None
Temperature: Cold tolerant to 20oF and heat tolerant to 120oF.
Light: In Phoenix, mostly full sun. Some protection from western afternoon summer sun to maintain normal foliar color. Full sun in southern California. Will tolerate only limited partial shade conditions.
Soil: Tolerant of all soil textures as long as the soil is well drained. This agave is moderately salt tolerant.
Watering: In Phoenix, infrequent deep waterings during summer every one to three weeks depending on soil texture, but in southern California only very little to no supplemental water is needed. Supplemental water somewhat increases plant growth rate and eventual size.
Pruning: None required.
Propagation: Division of basal offshoots, tissue culture.
Disease and Pests: Agave snout weevil (Scyphophorus acupunctatus) will attack many agave species in the low desert of Arizona.
Additional comments: Royal Spine agave is a very handsome, dimunative "designer desert" succulent that is noteworthy for its dense clumping habit.
Taxonomic speculations: It is fabled that the cultivar and common name 'Royal Spine' came from its two parents; the specific epithet macroacantha is latin for "large spine" and Agave victoriae-reginae was named for that most famous "royal", Queen Victoria.
