Sometimes considered a distinct species, littleleaf or dwarf mountain-mahogany is typified by (as you might guess) its small, coriaceous (leathery), linear leaves. As noted by the Flora of North America entry for Cercocarpus ledifolius var. intricatus, the leaves are also strongly revolute; the margins of the leaves are rolled downward against the underside of the leaf such that the lower (abaxial) surface is barely exposed to the open air.
This adaptation is one of several in this taxon that is often considered to be important for water retention. Revolute leaves reduce the surface area of the leaf exposed to the surrounding air’s lower humidity (or, water vapour concentration). They also structurally produce a pocket, such that wind shear is a much lower factor in water vapour loss through evaporation. Species of Cercocarpus in dry climates (like this one) double-down on this strategy: the stomata, sites of gas exchange in the leaves, are also depressed into the epidermis of the leaf–pockets on a smaller scale, but benefiting from the same principles. The trade-off for the overall approach of extreme water retention is slow growth; gas exchange, necessary for growth, is slowed through these small leaves, even in ideal conditions. However, plants of Cercocarpus have another strategy for when a favourable season for growth occurs.
Heteroblasty is the ability of some taxa, like Cercocarpus spp., to produce different types of leaves depending on shoot age and/or shoot length. As the authors of the Flora of North America entry on Cercocarpus note:
Cercocarpus species are heteroblastic, with new growth occurring in favorable seasons via long shoots, but with most leaves produced on flower-bearing short shoots. All but one species, C. montanus, are evergreen. Long-shoot leaves are larger than short-shoot leaves. Short-shoot leaves are variable in size with the proximal smallest, more ovate, the later-formed larger, often more oblong-obovate.
The authors seem to be suggesting that when long shoots are produced during favourable seasons, larger leaves are produced on these (at least temporarily), allowing plants to capitalize on the (relatively) abundant water while still retaining the short-shoot leaves over the long-term for those more-typical times of drought-stress. And, drought-stress would be the prevailing state for littleleaf mahogany, given that it lives on
Exposed, rocky slopes, ledges, bluffs with shallow soil, often cracks and crevices, alluvial slopes of limestone, dolomite, sandstone, or granite.
As you can see from this photograph, plants occasionally suffer dieback when water isn’t sufficient to maintain the entire plant–though the drought-stress would have to be severe (death to most plants without similar adaptations!).
For those geologically-inclined, the sandstone in the background is, as mentioned on the Coyote Buttes Wikipedia page, cross-bedded aeolian Jurassic Navajo Sandstone.