Crataegus (sect. Douglasia) ser. Douglasianae
Man. Cult. Trees ed. 2, 368. 1940.
Shrubs or trees, 25–100 (–140) dm. Stems: twigs: new growth glabrous, sometimes pubescent, 1-year old usually tan to deep mahogany; bark on younger 2–5 cm thick branches mainly dark gray-brown or orange, conspicuous horizontal lenticels absent; thorns on twigs recurved or straight, dark-brown, shiny young, usually ± stout, 1–3.5 cm. Leaves: petiole 0.7–1.5 (–2.2) cm, glabrous or pubescent, eglandular or glandular; blade broadly elliptic or elliptic to ± obovate, rhombic, oblanceolate, or ovate, 3–5 (–8) cm, chartaceous to coriaceous, base usually cuneate, lobes 0 or 2–4 per side, sinuses shallow, lobe apex obtuse to subacute, margins serrate, teeth apices glandular, venation craspedodromous to semicamptodromous (in some forms with lobes absent), veins (3 or) 4 or 5 per side, apex usually acute, sometimes obtuse, abaxial surface usually glabrous except on veins, sometimes sparsely pubescent, adaxial usually appressed-pubescent. Inflorescences (7–) 12–20 (–25) -flowered; branches glabrous or pubescent; bracteoles caducous, linear, small, membranous, margins stipitate or sessile-glandular. Flowers (10–) 12–15 (–20) mm diam.; hypanthium pubescent or glabrous; sepals 3–4 (–5) mm, margins subentire, finely glandular distally; stamens 10 (–20), anthers pink, sometimes puce; styles 3–5. Pomes black or dark purple mature, ellipsoid to suborbicular, 6–10 (–12) mm diam., glabrous or sparsely pilose; sepals reflexed or patent-recurved; pyrenes 3–5, sides plane to pitted.
w, c North America
Species 5 (5 in the flora).
Series Douglasianae comprises mainly western, widespread, black-fruited hawthorns, one of which, Crataegus douglasii, extends disjunctly to central Ontario. Its species are notable for their usually laterally pitted pyrenes, relatively short thorns, short and often blunt fruiting sepals, and dark purple to black fruits at full maturity.
|1||Stamens 20; thorns 1–2(–2.5) cm; leaf blades: lobes 0, or 2 or 3 per side, lobe apices acute to obtuse; pomes suborbicular to broadly ovoid.||Crataegus gaylussacia|
|1||Stamens 10(–18); thorns (1.5–)2–3.5 cm; leaf blades: lobes 2–4 per side, lobe apices subobtuse to acute; pomes ellipsoid to suborbicular, ± oblate, or ± ampulliform-orbicular||> 2|
|2||Inflorescence branches and hypanthia sparsely to densely pubescent, sometimes glabrous; thorns very few to many, some paired or in triads; pomes orbicular or ± oblate (recessed at junction with pedicel).||Crataegus castlegarensis|
|2||Inflorescence branches and hypanthia glabrous, sometimes ± sparsely pubescent; thorns single; pomes suborbicular to ellipsoid||> 3|
|3||Thorns 2 cm; flowers 15–20 mm diam.; pomes ± ampulliform-orbicular, red-burgundy to chestnut or reddish brown (late Aug), often shiny and usually with little bloom when ripe.||Crataegus okennonii|
|3||Thorns (1.5–)2–3.5 cm; flowers 10–15 mm diam.; pomes usually ellipsoid, rarely suborbicular, usually already very deep purple or dull black mature (late Aug), often still glaucous when ripe||> 4|
|4||Pyrene sides excavated, sometimes only shallowly; leaf blades elliptic to broadly elliptic or subrhombic, lobe sinuses usually shallow, lobe apices subobtuse to acute; thorns (1.5–)2–3.5 cm; pomes usually ellipsoid, 6–8 mm diam., vinous and usually very waxy glaucous young (mid Aug), dull black mature; sepal remnants reflexed, apices obtuse; stamens 10.||Crataegus douglasii|
|4||Pyrene sides plane to ± concave, grooved, or irregularly scarred; leaf blades rhombic, lobe sinuses deep, lobe apices acute; thorns 2–3 cm; pomes suborbicular to ± broadly ellipsoid, 12 mm diam., brick red young (mid Aug), deep purple mature, ± glaucous; sepal remnants patent-recurved, apices acute; stamens 10–18.||Crataegus shuswapensis|