Dasylirion longissimum aka Beargrass

Dasylirion longissimum is a shrub that keeps its leaves year-round. It belongs to the asparagus family, Asparagaceae. Its common names are Mexican grass tree and toothless sotol. It comes from San Luis Potosí to Hidalgo, Mexico. There, it grows in desert and dry shrubland. Its shape looks like a small palm with a round leaf crown. It grows slowly and can live beyond 150 years.

A woody trunk takes many years to form beneath the crown. It reaches about 3–6.6 feet [0.9–2 metres], sometimes more. Most plants have one trunk. Old plants may branch after they bloom. Hundreds of stiff, narrow leaves spread from the top. Their grey-green to blue-green blades grow 3–5.9 feet [0.9–1.8 metres] long. Each leaf has four sides in cross section and feels like leather. Old leaves hang round the trunk in a rough skirt. Taking off these leaves shows leaf bases in a spiral.

Plants may go years between blooms, then flower in summer. Male flowers and female flowers grow on separate plants. The flower stalk rises 6.6–9.8 feet [2–3 metres]. It can reach 16.4 feet [5 metres]. Many small flowers form branched groups near the stalk's top. Reddish buds open to cream, white, tan, or brownish yellow flowers. If fertilization succeeds, the fruit plume turns red-pink in autumn. Each dry fruit has three wings and holds one seed. It stays closed and does not split to shed its seed.

This shrub grows well in hot, dry places. It can withstand severe drought. It needs soil that lets water drain away very fast. It can cope with some moisture and damp air. The soil must still drain well. LLIFLE says it lasts well and needs little care. Its slow growth means the trunk takes years to form. Growers can start new plants from seeds or available cuttings.

The round crown gives gardens a strong shape all year. The leaf skirt and bare trunk give two different looks. Plants sold under this name may not all be the same. LLIFLE notes confusion with Dasylirion quadrangulatum. Some authors treat that as a distinct plant. LLIFLE describes D. longissimum as smaller, greyer, and less neat. Small teeth near the broad leaf bases may help tell it apart. The supplied sources give no clear evidence on food use or toxicity.