Mosquito Range mustard, also known as Penland alpine fen mustard, is a small perennial plant species in the mustard family. Though the mustard family itself is large, Mosquito Range mustard is one of only two species within its genus (Eutrema) found in North America. Mosquito Range mustard was first collected near Hoosier Pass in 1935 by C. William T. Penland, a professor of botany at Colorado College.

The species occurs only in alpine meadows at elevations above 11,800 feet in the Mosquito Range of the Rocky Mountains in central Colorado. Plants are most often found along east facing, gentle slopes and basins that are fed moisture by slow-melting snowfields above. However, they can also be found in dryer locations. In either habitat, they are often rooted in tufts of mosses or hidden among short-bladed grasses.

This harsh alpine environment is also home to many other rare plant species known only to the Rocky Mountains. Mosquito Range mustard is threatened by activities that damage its sensitive habitat or alter local hydrology. Because of the Mosquito Range’s spectacular views and scenery, it is a draw for recreation, especially in the summer months. Recreation activities like off-road vehicle use, including winter travel, camping, hiking, and roads could pose a threat to Mosquito Range mustard and its habitat. Land development, including mining, may also have a negative impact on the species. In addition, we do not fully understand how climate change climate change
Climate change includes both global warming driven by human-induced emissions of greenhouse gases and the resulting large-scale shifts in weather patterns. Though there have been previous periods of climatic change, since the mid-20th century humans have had an unprecedented impact on Earth's climate system and caused change on a global scale.

Learn more about climate change will affect the species or the habitat in which it resides. These factors make it difficult to predict the impacts of climate change to the Mosquito Range mustard. However, given that the species already resides at elevation extremes where there is nowhere to migrate higher, and given that the species is dependent on snowmelt and wet conditions, we expect that the Mosquito Range mustard is vulnerable to anticipated trends.

The author of the Colorado Flora considers Mosquito Range mustard (E. penlandii) to be a variety of E.edwardsii, hence the synonym E. edwardsii var. penlandii. Mosquito Range mustard was recently synonymized with E. edwardsii in the Flora of North America listing. In contrast, another study has found Mosquito Range mustard and E. edwardsii to be distinct from one another based on novel alleles, genetic diversity patterns, differences in morphology, or morphometric measurements, and chromosome counts. Further research is underway that will provide a more comprehensive overview of the relationship between Mosquito Range mustard and E. edwardsii.