Pronounciation: AL-o mar-lo-THEE-i

Hardiness zones
Sunset 12 and 13 with protection, 16-24
USDA 9-11

Landscape Use: In Phoenix, mountain aloe is a great accent plant for mixed canopied xeric gardens with some sun protection, container plant.

Form & Character: Upright, stiff, somewhat uncontrolled, striking, tree like with age.

Growth Habit: Evergreen, succulent, herbaceous perennial that is arborescent in habit growing a central stem that grows to 10-feet tall, although usually smaller in Phoenix due to the extreme summer heat.

Foliage/texture: Glaucous-green succulent leaves having a range of short, stout spines (yellow to reddish brown), leaves that taper to a blunt tip and are sometimes up to 3 to 4-feet long. Young, smaller plants grow leaves that are densely arrayed with spines, particularly on the abaxial (lower) surface. Older, taller plants grow leaves with fewer spines, dried leaves are persistent on the stem and form a dense rattling brown skirt. Mountain aloe is strongly coarse textured.

Flowers & fruits: The inflorescence is a much-branched panicle with up to 30 or more racemes. Individual flowers are tubular in thick brushlike clusters, yellow through orange (most common) to bright red. Fruit are a multiocarpulate capsule, generally unattractive.

Seasonal color: Brilliantly-colored, spectacular winter flowers.

Temperature: Mountain aloe is cold hardy to 23^oF, but suffers heat damage when summer temperatures exceed 112^oF.

Light: As with most Aloe species in central Arizona deserts, light shade or protection from western afternoon sun is best.

Soil: Tolerant, but well drained is best.

Watering: Infrequent irrigations during the summer.

Pruning: None except removal of dead flower stalks.

Propagation: Seed and stem cuttings, occassionally division of basal clumps.

Disease and pests: None

Additional comments: Mountain aloe flowers attract hummingbirds when in bloom. Mountain aloe is similar in appearance (except for its inflorescence with distinctively horizontal branches) and landscape use to Aloe ferox. Neither of these majestic aloes are commonly seen in Phoenix landscapes because of their difficulty in tolerating the exterme summer heat.

Taxonomic tidbit: The species name, marlothii is named after Rudolf Marloth, a German-born South African botanist.

Biomedical factoids: Mountain aloe is a succulent with many indigenous uses.