Agave isthmensis

Agave isthmensis is a small-sized botanical species, native to Oaxaca, Mexico. It forms a rosette composed of short and very wide leaves, with a beautiful grey-blue colour with green reflections. The leaves end in a long spine and are bordered by small, decorative, reddish-brown spines. This succulent plant is not very hardy, but it is perfectly resistant to summer drought. In warm climates, it will thrive in an exotic rockery. In cool regions, it should be grown in pots, which allows it to be sheltered in winter. 

Agave isthmensis, similar to Agave seemaniana, was only discovered in 1993 and is still a rare species in cultivation, making it difficult to assess its hardiness. Several sources indicate that it dies below -3°C (26.6°F) in dry soil. It belongs to the Asparagaceae family (formerly Agavaceae), just like Yuccas or tuberose. This perennial herbaceous succulent plant has rhizomes capable of producing suckers, but it is almost devoid of an above-ground stem, which takes the form of an extremely short, single trunk. The rosette will not exceed 50cm (20in) in diameter and about 60cm (24in) in height. Its growth is quite slow. It is composed of succulent, grey to glaucous, pruinose leaves with a marbled appearance. The leaves are thick, rigid, and spatulate. The leaf margins bear reddish-brown spines measuring 0.5 to 1.5cm (1in), which curve downward. Each leaf ends with a long, shiny, reddish-brown spine. When a rosette reaches the venerable age of 15 to 20 years, or even more, it produces a tall flowering stem with numerous horizontal branches. The branches bear flat and spherical panicles, composed of a myriad of small yellow-green tubular flowers. The rosette, known as semelparous, dies after several months of flowering. Adult plants produce a few daughter rosettes just below the mother rosette.

In very mild climates, this agave will find its place in a rockery, on a dry slope, or in a raised bed with soil enriched with gravel or coarse sand. It can be planted with prickly pears, other agaves, fairly hardy candelabra cacti (Cleistocactus strausii, Cylindropuntia imbricata), and ground-covering plants such as Ajania pacifica, all of which are equally undemanding. Gardeners in colder regions should grow it in full sun in a large pot on a terrace, carefully choosing the most sheltered spot to recreate a landscape inspired by the vast arid and wild spaces of Mexico. This plant should be overwintered in a very bright, airy place with minimal heating.