Polemonium pectinatum

Polemonium pectinatum is a species of flowering plant in the phlox family known by the common names Washington Jacob's-ladder and Washington polemonium. It is endemic to the state of Washington in the United States, where it occurs in the Columbia Basin, including the Channeled Scablands and the Palouse.[1]

Polemonium pectinatum
Conservation status
Imperiled  (NatureServe)
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Ericales
Family:	Polemoniaceae
Genus:	Polemonium
Species:	P. pectinatum
Binomial name
Polemonium pectinatum Greene

This perennial herb grows from a taproot, producing a cluster of stems up to 80 centimeters tall. The alternately arranged leaves are each made up of several linear-shaped leaflets up to 5 centimeters long. The hairy, glandular inflorescence is an open array of white or lavender flowers with five corolla lobes.[1][2] Flowering occurs in May through July.[1]

This species occurs in riparian habitat and seasonally moist depressions and bottomlands.[1][2] Other species in the habitat may include Crataegus douglasii, Amelanchier alnifolia, Elymus cinereus, Rosa woodsii, and Ribes aureum.[3]

There are about 26 occurrences of this species, divided into 6 or 7 populations. The plant's total distribution covers less than 2500 acres.[1]

Threats to the species include overgrazing, though it can tolerate some grazing activity, being adapted to disturbance. Land use conversion is a threat, for example, the conversion of the Palouse grasslands to agriculture. Other threats include alterations in hydrology, herbicides, and introduced species.[1]