11. Crataegus atrovirens J. B. Phipps & O’Kennon, Sida. 20: 141, fig. 10. 2002.
Shrubs, 20–50 dm. Stems ˂multiple, suberect to erect˃; twigs: new growth pubescent, 1-year old glossy brown, older dark gray; ˂bark on 2–5 cm thick branches gray-brown˃; thorns on twigs ± straight to very slightly curved, ± slender, 3–5 cm, 2-years old dark brown, black at tip, older deep gray. Leaves: petiole length 15–20% blade, sparsely or densely (in adaxial sulcus mature) hairy, eglandular or sparsely small glandular mainly distally; blade ˂dark green (in fall turning bronze-brown), matte˃, narrowly ovate to broadly elliptic-rhombic or broadly elliptic, 4–6(–7) cm, subcoriaceous, base cuneate, lobes 3 or 4 per side, small, ˂max LII ca. 10%˃, lobe apex acute, margins serrulate, ˂minutely glandular at apices˃, veins 3–5 per side, apex acute to subacute, ˂matte˃, abaxial surface glabrate, vein pubescence not recorded, adaxial scabrous hairy, glabrescent. Inflorescences 12–20-flowered; branches densely spreading-pubescent; bracteoles ˂narrow but widened distally˃, margins densely glandular. Flowers 10–14 mm diam.; hypanthium pubescent; sepals narrowly triangular, 4–5 mm, margins strongly glandular-serrate, abaxial pubescence not recorded; stamens 10(–20), anthers pink; styles 2 or 3. Pomes burgundy (late Aug), blackish purple (Sep), dull, ± ovoid, 13–15 × 10 mm, hairy; ˂flesh soft orange˃; sepals suberect, wide, 4–6 mm; pyrenes 2 or 3, sides pitted.
Flowering May; fruiting Sep–Oct. Natural hedgerows, brush in valleys, dry habitats; 300–500 m; B.C.
Crataegus atrovirens is known from the northern Okanagan, where it is locally common to abundant. One of its most notable characteristics are the unusually large glands on the leaf teeth. It also has smallish flowers for its series. Of species known to date from this region, C. shuswapensis is the one most likely to be confused with C. atrovirens. The mature fruit and the growth habit of C. shuswapensis are similar, but that species has leaves more sharply lobed, glabrous inflorescences, sometimes 15–18 stamens per flower, redder fruit in the fourth week of August, much smaller, less prominent fruiting sepals, whose margins, rather than being serrato-laciniate, are minutely glandular. Crataegus atrovirens also has similarities to C. okanaganensis; it is easily differentiated in the field by the usually much longer thorns, smaller flowers with pink anthers, and much darker fruit in late August. Compared to C. orbicularis, the fruit of C. atrovirens is also conspicuously larger; it is soft and ripe in the fourth week of August when the former is hard but not ripe. The erect, multi-trunked habit is also somewhat distinctive. It is a dull hawthorn, somber in appearance, contrasting markedly with more colorful congeners such as C. okanaganensis.