64c.2. Crataegus Linnaeus (sect. Douglasia) ser. Cerrones J. B. Phipps, Canad. J. Bot. 76: 1872. 1999.
Shrubs or trees, 30–50 dm. Stems: twigs: new growth glabrous or sparsely hairy, 1-year old reddish tan, reddish mahogany, or red-purple, older gray or copper-colored; bark on younger 2–5 cm thick branches mainly dark gray-brown or copper-colored, horizontal lenticels present; thorns on twigs straight or recurved, 2-years old black or purple-black, glossy or shiny, slender, 1–4 cm. Leaves: petiole ˂slender˃, 0.8–2.5 cm, pubescence and glandularity not recorded; blade ± elliptic to rhombic-elliptic, 3–8 cm, thin to coriaceous, base cuneate, lobes 0 or 3 or 4 per side, sinuses shallow, lobe apex acute, margins shallowly crenate or serrate, venation craspedodromous to semicamptodromous, veins 4 or 5(–12) per side, apex usually acute, sometimes obtuse, abaxial surface glabrate or glabrous mature. Inflorescences 5–12-flowered; branches glabrous, ˂usually glandular-punctate˃; bracteoles caducous, linear, membranous, margins usually sessile-glandular, sometimes eglandular. Flowers (10–)14–18 mm diam.; hypanthium glabrous; sepals (1.5–)3–4(–8) mm, margins subentire or entire; stamens 10(or 20), anthers pink or pink-purple to purple, sometimes cream; styles 3–5. Pomes deep red to vinous purple or black, orbicular, (8–)10 mm diam., glabrous; sepals suberect to reflexed; pyrenes 3–5, sides excavated.
Species 3 (3 in the flora): w United States.
Series Cerrones was initially treated among the red-fruited series (J. B. Phipps 1999b) as it was then understood only from its type species, Crataegus erythropoda, which has the least typical fruit color for the series. Series Cerrones contains two closely related species of intermontane hawthorn to which C. saligna, formerly placed in ser. Brachyacanthae, has been added. Series Cerrones is characterized by copper-colored mature bark, sometimes displaying horizontal lenticels, fine and short thorns, early caducous, few gland-margined bracteoles, burgundy to black mature fruit, and pyrenes with lateral excavations.
SELECTED REFERENCE Phipps, J. B. 1999c The relationships of the American black-fruited hawthorns Crataegus erythropoda, C. rivularis, C. saligna and C. brachyacantha to C. ser. Douglasianae (Rosaceae). Sida 18: 647–620.