Trifolium thompsonii

Trifolium thompsonii is a species of flowering plant in the legume family known by the common name Thompson's clover.[1] It is endemic to Washington state in the United States, where it occurs in two counties.[2][3] One of the largest populations occurs in the Entiat Slopes Natural Area Preserve in Chelan County.[4]

Trifolium thompsonii
Conservation status
Imperiled  (NatureServe)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Rosids
Order:	Fabales
Family:	Fabaceae
Genus:	Trifolium
Species:	T. thompsonii
Binomial name
Trifolium thompsonii Morton

This is a large clover with a thick stem growing up to 60 centimeters tall. The leaves are divided into three to eight serrated leaflets. The inflorescence is a round head of several bright red-lavender flowers. Blooming occurs in May through July.[2][3] Pollinators include bumblebees and the Greenish Blue, a butterfly.[2]

This species grows in several types of habitat.[2] One study identified four plant associations that include the clover. 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. The Artemisia vaseyana/Agropyron spicatum association includes Artemisia tripartita, Poa secunda, and Festuca idahoensis. A third association, the Pinus ponderosa/Agropyron spicatum has sparse tree cover, a grass understory, and no tall shrubs. 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.[5]

A Research Natural Area, the Thompson Clover Research Natural Area, was established in 1977[2] in the Wenatchee National Forest for the study and protection of this species.[6]