Muhlenbergia emersleyi Seeds | Bull Grass

Bull grass with arching blue-green leaves and purplish-bronze seed heads — Bull Grass (*Muhlenbergia emersleyi*): Poaceae, mountain slopes of the southwestern United States and northern Mexico.

LATIN NAME: Muhlenbergia emersleyi

COMMON NAME: Bull Grass, Emersley’s Muhly

Plant Profile

Bull grass is a clump-forming perennial of the mountains of Arizona, New Mexico, western Texas and northern Mexico, growing sixty to a hundred centimetres with stiff, blue-green leaves that arch outward from a dense crown. In late summer it sends up slender stems carrying loose, purplish-bronze panicles that fade to a pale straw colour and persist into winter. It grows on rocky slopes and in canyon country at fifteen hundred to two thousand five hundred metres, where it tolerates heat, drought, cold and poor, stony soil. It is one of the most drought-tolerant of the muhly grasses, and it is used in dryland landscaping across the Southwest. Unlike pink muhly, its colour is in the seed heads rather than in pink hairs, and it holds its form through the winter.

Science & Biotechnology

Muhlenbergia emersleyi is a C4 grass of the Chloridoideae, and its blue-green colour comes from a waxy leaf cuticle that reflects light and reduces water loss. The species is adapted to the transition zone between desert and mountain, where it receives winter snow and summer rain, and it grows in a range of soils from limestone to volcanic. Its seed heads are produced on long, slender culms that sway in the wind, an adaptation that helps disperse the small seed. The plant is a poor competitor in rich soil, where it is shaded out by taller grasses, and it is at its best on shallow, rocky ground where nothing else grows. It is being evaluated as a low-input turf alternative and for restoration seeding on disturbed dry sites, and it has no invasive record outside its range.

Uses & Benefits

The grass is planted as an ornamental for dry gardens, rock gardens and commercial landscapes, where its blue foliage and bronze seed heads give year-round structure with no irrigation. It is also used for erosion control on dry slopes and for restoration seeding. The seed heads are used in floristry, fresh and dried. It provides cover for small wildlife and its seed is eaten by birds. In the garden it needs full sun, sharp drainage and poor soil, and it should be cut back to fifteen centimetres in late winter. It is more cold-hardy than pink muhly and tolerates alkaline soil, which makes it useful where the pink species fails. Divide the clumps every three or four years.

Growing from Seed

Sow the seed on the surface of a gritty mix in spring, press it in, and cover with a bare millimetre of grit. Keep at twenty to twenty-five degrees in bright light; germination takes two to three weeks. The seedlings are slow and should be grown on in deep pots, since the plant makes a substantial root system. Plant out into gravelly or stony soil in full sun, and water only in the first summer. Do not enrich the soil, and do not irrigate once established, which makes the plant floppy and short-lived. Cut back in late winter before new growth. Divide every three or four years, replanting the vigorous outer pieces.

Our Take

A blue-leaved muhly with bronze seed heads and a taste for stony ground. Dry, sunny, cold-hardy and cut back in late winter.

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