Cypress Hills hawthorn

Shrubs or trees, ˂± erect˃, 25–60 dm. Stems: twigs: new growth ˂greenish red young˃, sparsely pilose, 1-year old deep to reddish brown, shiny, older orange-brown overlaid with gray; ˂bark on 2–5 cm thick branches orange-brown˃; thorns on twigs ˂few to numerous˃, ± straight to strongly recurved, slender, 3–7 cm, 2-years old blackish brown. Leaves: petiole 1–2 cm, sparsely hairy young, sparsely glandular; blade ± ovate to broadly elliptic, 3–6 cm, thin, base broadly cuneate, lobes 3 or 4 per side, ˂max LII ca. 15%˃, lobe apex acute to ± rounded, margins serrate, ˂teeth numerous, small, gland-tipped when young˃, veins 3 or 4 per side, apex acute, ˂shiny˃, abaxial surface glabrate, some axils of midvein pilose, adaxial appressed-hairy. Inflorescences 5–15-flowered; branches sparsely to moderately or densely pilose; bracteoles ˂pale brownish˃, margins nearly eglandular, minutely short, delicately stipulate-glandular. Flowers 15–18 mm diam.; hypanthium glabrous; sepals ˂± anthocyanic˃, triangular, length not recorded, margins finely glandular-serrate, abaxially glabrous, ˂adaxially pilose˃; stamens 10, anthers white; styles 3–5. Pomes ˂on pendulous branches˃, burgundy (Aug–early Sep), black (late Sep), glossy, ellipsoid, 7–10 mm diam., glabrous; sepals spreading, wide, 3–4 mm, ˂apex ± acuminate˃; pyrenes 3–5, sides ± irregularly pitted or scarred.

Flowering late May–early Jun; fruiting Aug–Sep. Thickets, grasslands, light shade of Populus spp.; 800–1200 m; Alta., Sask.; Mont.

Crataegus cupressocollina is found through much of the Cypress Hills, where it may be common, and in a restricted area in the Bear's Paw Mountains, Montana. The species is distinctive in its tall, willowy, upright habit, leaf form, relatively long, slender thorns, and two to five year-old orange-brown bark. The flowers differ from those in ser. Douglasianae in their white anthers. The ripe fruit of C. cupressocollina is glabrous and plum red to purple-brown in late August, after which it ripens to a glossy purple-black. The large, pendulous clusters of fruit at once draw attention, as do the reddish tips of the sepals and the soft red-brown of the often nearly eglandular bracteoles when in flower. The colorful expanding bud scales are also rather striking. Crataegus cupressocollina is the first to flower of sympatric species.