Malus fusca

Malus fusca is a wide-ranging small tree or shrub found in moist or wet seepage sites in open places, natural or disturbed, including temperate coniferous forests, such as open Sitka spruce forests, forest edges, beach edges, sea cliffs, swamps, bogs, brackish marshes, and clearings. It occurs in western North America from Alaska, United States, south through British Columbia, Canada, to California. There are over 1,200 estimated occurrences, which face threats from mammal herbivory, hybridization with cultivated apples, and climate change. Little is known about trends, but with a large range extent and large number of occurrences, abundant habitat, and broad habitat preferences, this species is considered secure.

Malus fusca occurs in western North America from the Kenai Peninsula in Alaska, United States, south through British Columbia, Canada, to northern California (FNA 2014, Roulston et al. 2025). Range extent was estimated to be approximately 2.3 million square kilometers using herbarium specimens and photo-based observations documented between 1994 and 2025 (GBIF 2025, iNaturalist 2025, RARECAT 2025, SEINet 2025).

By applying a 1 km separation distance to herbarium specimens and photo-based observations documented between 1994 and 2025, it is estimated that there are over 1,200 occurrences rangewide (GBIF 2025, iNaturalist 2025, RARECAT 2025, SEINet 2025). This species may be cultivated, and occurrence data was not thoroughly evaluated for evidence of cultivation.

Native Crabapples (Malus) in eastern North America face numerous threats, with fewer threats documented for the western North American species. The primary threats for Malus fusca appears to be mammal herbivory, and new, emerging threats from hybridization with cultivated apples and climate change have unknown impacts on future impacts to native Malus populations.

Mammal herbivory has been documented in native populations of Malus in North America. Large mammals, such as North American beaver and Sitka black-tailed deer, can negatively affect populations of Malus (Roulston et al. 2025).

Wild populations of Malus also face threats from introduced genetic material from hybridization with cultivated plants. While the introgression between M. fusca and cultivated Malus has been historically documented in Oregon, current levels of introgression are unknwon (see references in Roulston et al. 2025).

Climate change is likely to have a strong impact on Malus populations. The life history of Malus species, as woody perennials with long generation times and extended juvenile phases, may inhibit adaption to climate change. Milder winters may reduce cold hardiness, shifting to earlier timing of plant phenology (such as earlier flowering, potentially mismatching with pollinator availability), increasing damage to flowers or flower buds from late-spring frosts, and increasing abundance or expanding distribution of pests and pathogens (Roulston et al. 2025). Alteration in rainfall patterns and water availability during the growing season may lead to increased droughts or prolonged wetness (Volk et al. 2015a). Range shift models predict poleward expansion by 2070 (Roulston et al. 2025).