Mountain Mahoganies Cercocarpus

Of four assessed members, one is rated fire resistant, one is rated keep away, and two were assessed without the sources taking a side. The resistant finding belongs to mountain mahogany identified only as Cercocarpus sp., and rests on a handful of assessments. Its cited guidance says it tends to resist ignition when irrigated and maintained. Alderleaf mountain mahogany, by contrast, is rated keep away with a substantial body of assessment behind it.

Testing of alderleaf mountain mahogany reported 41% foliage moisture, peak heat release of 141 kilowatts per square metre for a green sample, and effective heat of combustion of 15.8 megajoules per kilogram for a dry sample. Those figures describe the tested material, but they do not make every Cercocarpus shrub behave alike. The U.S. Forest Service adds another species-specific warning: curl-leaf mountain mahogany is usually killed by fire, with heavy mortality common after most fires. Some mature plants survive light fires where litter is low and fuels are mainly grasses, but that survival does not apply to the genus as a whole.

These Rosaceae shrubs are native across broad parts of the western and central United States. For a homeowner choosing among them, the plant label matters: alderleaf mountain mahogany is the member to distinguish because its verdict is clearly unfavorable, while a generic mountain mahogany rating should not be extended to littleleaf, curl-leaf, or other named species.