Agave isthmensis

Agave isthmensis is a small succulent perennial from southern Mexico. Its common names include dwarf butterfly agave and maguey istmeño. It belongs to the Asparagaceae family. Its range covers parts of Oaxaca and Chiapas. The species name refers to the Isthmus of Tehuantepec. It grows in a tropical region with a dry season. Known sites include coastal hills and slopes farther inland. Near Salina Cruz, plants grow among grass and boulders. These give some shelter from the strong midday sun.

The plant forms tight rosettes and often makes nearby offsets. Most rosettes stay below 1 foot [0.30 m] tall and wide. The species varies in size across its range. Smaller plants reach about 0.4 feet [0.13 m] tall. Their width reaches about 0.7 feet [0.20 m]. Larger plants reach 1.05 feet [0.32 m] tall. These can spread to 1.2 feet [0.36 m] across. Plants near Salina Cruz tend to make fewer offsets. Each rosette may hold 84 to 132 closely packed leaves.

The leaves have a dusty grey-blue to pale blue surface. Their rough blades curve inward like shallow spoons. Each narrows at the base and widens toward the tip. Leaves usually reach 0.33–0.43 feet [0.10–0.13 m] long. Rounded lobes line the leaf edges. Dark red-brown or black teeth stand along these lobes. Smaller teeth may grow between the larger ones. Each leaf ends in a sharp, dark spine. Teeth can leave clear marks on the leaves beside them.

The flower stalk rises far above the low rosette. It reaches about 4.9–7.2 feet [1.5–2.2 m] tall. Short side branches carry clusters of fleshy yellow flowers. A rusty red flush can tint the blooms. The stalk begins to grow in summer. Flowers open in late summer, and capsules start ripening in autumn. The capsules are egg-shaped, with a small pointed tip. They hold small, flat, black seeds. Each rosette flowers once, then dies, while offsets can remain.

This species has sometimes been confused with Agave potatorum. Botanists recognised it as a separate species in 1993. Its smaller flowers and overall size helped distinguish it. Nearby populations of the two species can show intermediate forms. Plant labels in collections may therefore need careful checking.