Dasylirion
Dasylirion is a genus of evergreen, semi-succulent desert plants native to the southwestern United States and Mexico, prized for their dense, spherical rosettes of narrow, saw-edged leaves borne atop a short, stout trunk. Commonly known as sotol or desert spoon, these architectural rosette plants are mainstays of xeriscaping and dry-garden design, where their fine-textured, fountain-like silhouettes read almost like a giant grassy pincushion. Though often grouped with the agaves and yuccas in the hobby, Dasylirion belongs to the asparagus family, Asparagaceae.
Description
Plants in this genus form a single, symmetrical rosette of many hundreds of long, thin, strap-like leaves radiating in every direction, giving the whole plant a rounded, ball-like outline. The leaves are stiff and leathery rather than plump, and in most species their margins are armed with small, hooked, saw-tooth teeth that snag skin and clothing — a reliable field mark, though a few species, such as D. longissimum, have nearly smooth, toothless margins. Each leaf broadens at the very base into a pale, concave, spoon-shaped clasp where it joins the stem, which is the origin of the name desert spoon.
With age the rosette rises on a short, thick trunk, and older specimens can develop a woody caudex-like base. The plants are semi-succulent: they store water in their fibrous crowns and roots and endure long dry spells by simply slowing down. Dasylirion is dioecious, with male and female flowers on separate plants. Mature specimens send up a tall, narrow flowering spike — often several metres high — densely packed with small, creamy or straw-coloured flowers that tower well above the foliage.
Distribution
The genus is centred on the arid and semi-arid uplands of northern and central Mexico, extending north into Texas, New Mexico and Arizona. Typical habitat is open desert grassland, rocky slopes, limestone hills and the lower reaches of chaparral, usually on sharply drained ground. Several species are important components of the Chihuahuan Desert flora, where they grow alongside agaves, yuccas and prickly pears.
Notable species
- Dasylirion wheeleri — the classic desert spoon, with striking blue-grey leaves; the most widely grown ornamental species.
- Dasylirion longissimum — the Mexican grass tree, with very long, slender, quadrangular deep-green leaves and an especially soft, fountaining look; its leaf margins are nearly toothless.
- Dasylirion acrotrichum — the green sotol, a green-leaved species common in cultivation and landscaping.
- Dasylirion texanum — a compact, cold-tolerant Texan species well suited to garden use.
- Dasylirion leiophyllum — another hardy sotol of the Chihuahuan Desert with smooth, glossy leaves.
Cultivation
Dasylirion species are tough, low-maintenance and among the more forgiving desert plants to grow, provided their basic needs are met. Give them full sun — the more light, the tighter and more symmetrical the rosette — and a very free-draining, largely mineral mix or gritty garden bed. They resent sitting in wet soil, so raised beds, slopes or generously amended planting holes suit them well.
Water established plants sparingly; in the ground, mature specimens are highly drought tolerant and often thrive on rainfall alone once rooted in. In containers, water thoroughly when the soil has dried and allow the pot to dry out fully before the next drink. Feed lightly if at all. Many species tolerate light frost and short freezes, with the blue-leaved forms such as D. wheeleri and the Texan species being notably cold-hardy; even so, they appreciate sharp drainage in winter to prevent crown rot. See Watering and Repotting for general technique.
The saw-toothed leaf margins deserve respect — site plants away from paths and handle with gloves and long sleeves when planting or grooming. Old, dried leaves can be left as a "skirt" for a natural look or carefully trimmed away for a cleaner silhouette.
Hobby and landscape notes
Sotols are grown far more as bold structural landscape plants than as windowsill specimens. Their fine-textured, spherical form provides year-round evergreen presence in xeric and Mediterranean-style gardens, gravel gardens and modern architectural plantings, where they pair naturally with Agave, Yucca and desert grasses. The blue-leaved D. wheeleri is especially valued for its colour and its eventual tall flower spike, which persists as a dramatic seed stalk. Because the genus is dioecious and slow to reach flowering size, cultivar selection is limited compared with the more heavily bred cacti; plants are usually grown and sold simply by species. In their native range, several Dasylirion species are of cultural and economic importance and are harvested for the traditional Mexican spirit distilled from their hearts.
Propagation
Seed is the usual and most reliable method, as most species rarely offset. Sow fresh seed on a warm, gritty, free-draining surface and keep it lightly moist until germination, then grow the seedlings on hard in bright light; they are slow but steady. Because plants are dioecious, viable seed requires both a male and a female plant in flower, so hobby seed often comes from wild or botanic-garden sources. A few species may occasionally produce basal pups that can be separated once rooted. See Propagation — seed and Propagation — offsets for details.
See also
- Agave · Yucca · Nolina — related rosette-forming desert plants
- Soil and potting mix · Watering · Propagation — seed · Repotting · Pests and diseases