The Ecology of the North Cascades is heavily influenced by the high elevation and rain shadow effects of the mountain range. The North Cascades is a section of the Cascade Range from the South Fork of the Snoqualmie River in Washington, United States, to the confluence of the Thompson and Fraser Rivers in British Columbia, Canada, where the range is officially called the Cascade Mountains but is usually referred to as the Canadian Cascades. The North Cascades Ecoregion is a Level III ecoregion in the Commission for Environmental Cooperation's classification system.

Lewisiopsis tweedyi is a flowering plant and sole species in genus Lewisiopsis. The species, formerly known as Cistanthe tweedyi and Lewisia tweedyi, is now classified in the family Montiaceae. The plant is known by the common names Tweedy's pussypaws, Tweedy's lewisia, or Tweedy's bitterroot. It is endemic to western North America in north-central Washington and adjacent British Columbia. It commonly grows on well-drained slopes often on rocky slopes or in rock crevices from low elevation ponderosa pine sites up to the drier part of the Grand Fir zone of the North Cascades. The flowers usually have a coral, apricot, or pink color.