Crataegus (sect. Coccineae) ser. Populneae
Phytoneuron 2014–39: 1. 2014.
Shrubs or trees, (10–) 20–70 (–80) dm, main trunk dominant. Stems: trunk bark buff to gray-brown, fibrous, checked into longitudinal plates, freshly exposed bark orangebrown; branches spreading; twigs ± straight, new growth usually glabrous, sometimes pubescent, 1-year old reddish-brown or dark reddish-brown, sometimes tan, 2-years old ± gray, sometimes gray-brown or blackish, older paler gray; thorns on twigs moderately frequent, straight to recurved, 1-year old usually dark reddish-brown to blackish, usually shiny, usually slender, 2.5–5 cm. Leaves: petiole length (16–) 30–55% blade, glabrous, sometimes pubescent young, eglandular or sparsely glandular, usually sessile-glandular; blade mid to dark green adaxially, broadly elliptic to ovate or deltate, rarely suborbiculate or rhombic, 2–7 (–8) cm, chartaceous to subcoriaceous, base broadly cuneate or rounded to truncate or subcordate, lobes 3–5 per side, sinuses shallow to deep, lobe apex acute to acuminate, margins serrate, teeth numerous, venation craspedodromous, veins 3–5 (or 6) per side, apex subacute to acuminate, abaxial surface glabrous except sometimes veins, adaxial pubescent young. Inflorescences 4–10 (–12) -flowered, convex panicles; branches usually glabrous, sometimes pubescent; bracteoles caducous, absent or few, linear, membranous, margins sessile or short-stipitate-glandular. Flowers 14–18 mm diam.; hypanthium usually glabrous, sometimes pubescent; sepals triangular or lanceolate, much shorter than petals, margins subentire or shallowly to moderately glandular-serrate; stamens (6–) 10 or 20, anthers usually pink or rose to purple, rarely yellow; styles 3–5. Pomes usually bright red, sometimes orange-red, suborbicular to oblong or pyriform, 8–12 (–13) mm diam., usually pruinose, glabrous; flesh usually hard, sometimes mellow; sepals erose or persistent, sessile, patent to reflexed, nonaccrescent; pyrenes 3–5.
c, e North America
Species 8 (8 in the flora).
There is only one widespread member of this series, Crataegus populnea; C. aemula is locally common, and the others are sporadic in occurrence. Some species of ser. Populneae are difficult to separate from C. macrosperma in ser. Tenuifoliae, which usually has more fugacious bracteoles. Other species are closer to ser. Pruinosae. Some members of ser. Populneae may be of hybrid origin between these two series. The very rare and poorly known C. haemacarpa Ashe perhaps belongs here.
|1||Stamens 20.||Crataegus beata|
|1||Stamens 6–10, rarely 20 (C. jesupii)||> 2|
|2||Pomes oblong or pyriform-oblong to pyriform||> 3|
|2||Pomes suborbicular||> 6|
|3||Leaf blades subcoriaceous, sinuses shallow||> 4|
|3||Leaf blades thin, sinuses deep||> 5|
|4||Leaves blades ± ovate, length/width = 1.5.||Crataegus populnea|
|4||Leaf blades deltate-ovate to ovate, length/width = 1.1–1.2.||Crataegus prona|
|5||Leaf blades trullate-ovate, lobe apices often ± aligned.||Crataegus jesupii|
|5||Leaf blades ovate, lobe apices (at least proximal) not aligned.||Crataegus levis|
|6||Leaf blades: length/width = 1.8–2; anthers pale yellow.||Crataegus delawarensis|
|6||Leaf blades: length/width = to 1.5; anthers pink to purple||> 7|
|7||Leaf blades ± thin or chartaceous; petioles stipitate-glandular; inflorescence branches hairy.||Crataegus aemula|
|7||Leaf blades subcoriaceous; petioles eglandular or sessile-glandular; inflorescence branches glabrous||> 8|
|8||Leaf blades 4–7 cm; extension-shoot leaf blades widest at 2/5 distance from base, 1.3–1.4 times as long as wide, sinuses not deep (LII less than 25%), bases broadly cuneate, rarely truncate; pomes: flesh hard.||Crataegus populnea|
|8||Leaf blades 4–5 cm; extension-shoot leaf blades widest in basal 1/4, nearly as long as wide, sinuses deep (LII 25–50%), bases nearly truncate; pomes: flesh mellow when ripe.||Crataegus stolonifera|