64f.1. Crataegus Linnaeus (sect. Coccineae) ser. Virides (Gordon) Rehder, Man. Cult. Trees ed. 2. 364. 1940.
Crataegus sect. Virides Gordon in J. C. Loudon, Arbor. Frutic. Brit. 2: 847. 1838; Crataegus [unranked] Virides (Gordon) Sargent
Shrubs or trees, 80–150 dm, main trunk dominant. Stems: mature trunk bark dark gray or black, plated or whitish to light gray, thin-exfoliating, freshly exposed bark not recorded; ˂compound thorns on trunks present˃; twigs: new growth usually glabrous (not recorded in C. nitida), 1-year old gray to reddish brown or chestnut brown; thorns on twigs absent or few to abundant, usually straight, 1–2-years old blackish or chestnut brown, slender, 3–4 cm. Leaves: petiole ˂long˃, length 33–40% blade, adaxially glabrous or pubescent, usually eglandular, sometimes sparsely glandular; blade narrowly elliptic to suborbiculate, narrowly rhombic to oblong and ovate, oblanceolate, or broadly lanceolate to narrowly rhombic-elliptic, (2–)4–7(–8) cm, subcoriaceous or thin, base cuneate to rounded or tapered, lobes 0 or 1–3 per side, sinuses vary in depth (deepest LII 20–25%), lobe apex acute (obtuse in C. viridis var. ovata), margins strongly serrate to obscurely crenate-serrate in distal 1/2 only, venation craspedodromous, sometimes semicamptodromous, veins 3–5(–7) per side, apex acute to obtuse or acuminate, surfaces usually glabrous, except with tufts of hair in abaxial vein axils. Inflorescences 10(–50)-flowered; branches usually glabrous (densely hairy young in C. viridis var. velutina); bracteoles fugacious (not seen in C. nitida), linear-filiform, membranous, margins eglandular or sparsely glandular (somewhat glandular in C. viridis var. glabriuscula). Flowers (10–)13–15(–18) mm diam.; hypanthium usually glabrous (hairy in C. viridis var. velutina); sepals narrowly triangular, shorter than petals, margins ± entire or glandular-serrate; stamens 20, anthers usually cream or ivory, very rarely pale pink; styles 3–5. Pomes orange to deep red or brick red to red, rarely yellow, suborbicular, 5–8(–12) mm diam., usually glabrous; flesh mealy or hard; sepals usually recurved, sometimes spreading; pyrenes 3–5.
Species 2 (2 in the flora): sc, se United States.
Series Virides is widespread in the United States from Texas to Maryland in the coastal plain and inland to southeast Kansas and southern Illinois; it is absent from Appalachia except in deep river valleys. Taxa of ser. Virides are usually found in or at the edges of marshes, swamps, ditches, and streams.
Series Virides consists of one species complex and a narrowly defined species. The series is normally easily recognized by its nearly glabrous nature except for young adaxial leaf surfaces and abaxial leaf pubescence in axillary tufts. It is also barely glandular, has tall stature, usually exfoliating bark, pale gray bark on twigs to 5 mm diam., 20 stamens, cream anthers, narrowly linear, eglandular bracteoles, and orange to red pomes. Petioles are proportionately longer in the broad-leaved forms. Less common forms have colored anthers, larger fruit, or hairy foliage and inflorescences. Series Virides is perhaps most closely related to ser. Crus-galli.
The interserial hybrid Crataegus ×atrorubens keys out in the first couplet.