Trifolium thompsonii is a species of flowering plant in the legume family known by the common name Thompson's clover.

[2][3] One of the largest populations occurs in the Entiat Slopes Natural Area Preserve in Chelan County.

The Pseudotsuga menziesii/Calamagrostis rubescens forest habitat is a cooler, moister area with associated species such as Spiraea betulifolia, Penstemon fruticosus, Balsamorhiza sagittata, and Achillea millefolium.

Associated species include Eriogonum heracleoides, Phlox longifolia, Haplopappus stenophyllus, and Antennaria rosea.

The Artemisia tridentata/Agropyron spicatum association is a drier habitat which includes many forbs such as Allium acuminatum, Agoseris grandiflora, Lomatium nudicaule, and Lupinus sericeus.