Coleogyne ramosissima aka Blackbrush

Coleogyne ramosissima, called blackbrush, belongs to the rose family. This shrub comes from the southwestern United States, reaching Colorado. Its range includes parts of California, Nevada, Utah, and Arizona. It grows where warm and cold desert regions meet. Sites lie at elevations of 2,500–6,500 feet [760–1,980 metres]. Blackbrush can form broad stands with few other shrubs.

Oregon State gives its height as 1–4 feet [0.3–1.2 metres]. Virginia Tech reports plants reaching 5 feet [1.5 metres]. The shrub spreads low and forms a dense, rounded crown. Many stiff branches give it a close, tangled form. Branch tips often end in spines. Young twigs look gray and grow darker with age. Wet twigs also take on a darker shade. The bark ranges from dark gray to almost black. Shallow cracks show a lighter gray within the bark. This dark framework makes the whole shrub look black from afar.

The small leaves grow in opposite pairs and tight clusters. Each leaf has a narrow or slightly club-shaped outline. Leaves measure about half to three-quarters of an inch long. Their edges are smooth, without teeth or lobes. The foliage looks gray-green and has a scent. Blackbrush can keep its leaves when conditions allow. During drought, it sheds them instead. Its dark branches remain a strong part of its form.

Single flowers open at branch tips in early spring. Each flower has both male and female parts. Most lack petals, so the sepals supply the color. The four sepals range from yellow to yellow-brown. Their outer faces may show red tones. Each flower also holds many stamens. Small brown fruits follow and ripen in early summer. These dry fruits, called achenes, hold a single seed. Their shape ranges from curved to egg-shaped. They measure roughly one-eighth to one-quarter of an inch long.

For cultivation, Oregon State lists sun and dry, well-drained soil. These needs match its desert setting and drought-linked leaf loss. Its low crown, gray foliage, and dark stems define its appearance. Oregon State suggests USDA Zone 5, but marks that rating as uncertain. The supplied sources give no firm upper hardiness limit. They also give no evidence on edible parts or toxicity. Pest and disease concerns are not covered in these accounts.