The genus Aloe

The genus Aloe merits wider use, be it in a potted collection or in mixed plantings. More than any other plant, aloe vera is an icon of the 1960s and ’70s (at least within the realm of legality). It grew on nearly every countercultured windowsill in North America, offering its gelatinous sap to be smeared or swallowed for every known malady. This species, whose scientific name is Aloe barbadensis, was my entree to an assemblage of other species, ones that soothe the need for an impressive container plant or, in more temperate areas, a highly textural, drought-tolerant subject for the open garden.

Aloe, a genus of around 400 species, is currently found in the Asphodelaceae, along with the closely related genera Haworthia, Gasteria, and Kniphofia. The genus name doubles as the common name and as such has two syllables: AL-low. However, the correct scientific pronunciation has three: al-LOW-ee. Species occur naturally across Africa and the Arabic Peninsula, but the genus’s center lies in South Africa. There one can observe the enormous breadth of variation within the genus, from diminutive, herbaceous, and grasslike plants to magnificent round-crowned trees. Nectar-rich aloe flowers are primarily pollinated by sunbirds in these plants’ native haunts; in the Pacific Northwest, hummingbirds find them quite to their taste.

From the high steppe of Lesotho hails the rare spiral aloe, A. polyphylla. Polyphylla implies different leaves, but here it refers to the two different growth patterns within the species. This aloe’s succulent leaves unfurl in a spiral fashion; whether they go clockwise or counterclockwise depends on the genetics of the individual seedling. A remarkably hardy species, it tolerates temperatures as low as 10°F if planted in sharply draining soil. I grow this species under the southern eaves of my house, where it is protected from excessive winter rains. Branched stems capped by tubular orange flowers appear in early summer after the plant reaches sexual maturity. Now successfully in tissue culture, A. polyphylla has become more widely available in recent years.

Aloe striatula—one of the hardiest of the caulescent, or stemmed, aloes—does not seem to resent excessive winter moisture as long as the soil is quick to drain. It carries elongated fleshy leaves along multiple erect canes, which can grow to three and a half feet tall. Erect racemes of orange (fading to yellow) tubular flowers appear throughout the summer. The extremely wet and cold winter of 2007 killed my plants to the ground, but they quickly resprouted to form beefy low shrubs.

The so-called grass aloes are considered the hardiest of all, and my experience would verify just that. The thin light green leaves of A. cooperi emerge in spring, rising to 15 inches and appearing very Kniphofia-like. Simple racemes of pretty orange tubular flowers bloom—at least for us in the cool Pacific Northwest—from late summer into early winter. My plant was in full blossom when mid-teen frosts clobbered it last December, but it has returned unfazed.

Extremely different in appearance, though seemingly as hardy, is the hedgehog aloe, A. humilis var. echinata. Dense low rosettes spread outward by stolons, making a handsome mound of somewhat spiny dark green foliage in short order. My plant has done remarkably well, but it looks lilliputian next to specimens at Plant Delights Nursery in Raleigh, North Carolina.

Years since I tried an aloe vera smoothie to settle an uneasy stomach, my Aloe collection grows at an alarming rate, as does my appreciation for the ornamental effects this genus can bring to my garden.