Rubus nigerrimus (Greene) Rydb.

Washington: Whitman: [locality and coordinates withheld; status in Washington: G2/S2 (Threatened; WANHP)],
Along small stream. Plants erect then the branches arching or clambering, up to 8 ft. long; new shoots glaucous green; flowering canes brownish to bluish (glaucous) brown; leaves glabrous and only slightly paler on the lower, than on the upper surface; spines flattened and mostly hooked; petals white elliptic, flared, 5, but many flowers with 6, and occasional flowers with up to 10-13 petals; in the whole not quite so glaucous as #21860, but still fairly glaucous, especially on protected part of plant. Https://intermountainbiota.org/portal/collections/individual/index.php?occid=32796645. Phenology: flowering.

C.L. Hitchcock 21861, Jun 11, 1959
With C.V. Muhlick
WS, Catalog: 245228, WS025610