Coleogyne is a monotypic genus in the rose family containing the single species Coleogyne ramosissima, which is known by the common name blackbrush. This thorny, aromatic shrub is native to the deserts of the southwestern United States. It is a thickly branched thicket which may spread across the ground in clumps or grow erect to approach two meters in height. It is drought-deciduous, such that its branches are covered in clumps of fuzzy thick leaves until the hottest, driest parts of the desert year when it drops some of its foliage and becomes dormant for the season. This plant forms vast monotypic stands across the desert floor and on scrubby slopes. Flowering is triggered by a heavy spring rain in this desert-adapted species. The leathery flowers grow at the ends of small stems. They are encased in thick, fuzzy sepals which are yellow inside and reddish or orange on the outer surface. There are no petals, but the sepals remain after the flower opens, surrounding the patch of whiskery stamens and the central pistil. The fruit is an achene a few millimeters long. The plant reproduces from seed, but very rarely. The seeds do not disperse well and seedlings do not survive in large numbers. A narrow range of temperature and moisture is required for the reproduction of this species, so it is sporadic, but the plants are hardy and long-lived.