Crataegus sect. Macracanthae
Arbor. Frutic. Brit. 2: 819. 1838.
Shrubs or trees, 20–70 (–80) dm. Stems: trunks 1–several, ± erect to oblique, bark flattened-scaly; compound thorns on trunks present or absent; thorns on twigs determinate, recurved, usually stout, sometimes ± slender. Leaves: blade ± ovate or rhombic to rhombic-elliptic or broadly elliptic, 3–8 (–12) cm, coriaceous or thin, lobes 0 or 3–5 (–8) per side, sinuses shallow, max LII usually 20%, veins (3–) 5–8 per side, absent to sinuses. Inflorescences: branches usually pubescent; symmetric bracteoles present, basal bracteoles absent, falcate bracteoles absent. Flowers: post-mature petals pale paper brown; stamens 10 or 20, anthers red, pink, purple, sometimes white, ivory, or cream. Pomes orange to red; pyrenes dorsally grooved, sides ± pitted or eroded, sometimes plane.
Species 8 (8 in the flora).
Section Macracanthae is similar to some species of sect. Coccineae; it differs in possessing more or less pitted pyrenes.
|1||Pyrenes 2 or 3, (obtuse at ends), sides eroded; petioles usually eglandular.||Crataegus ser. Macracanthae|
|1||Pyrenes 2–5, (obtuse or acute at ends), sides ± smooth to erose or pitted; petioles usually glandular||> 2|
|2||Pyrene sides eroded, (always obtuse at ends); Great Plains.||Crataegus ser. Macracanthae|
|2||Pyrene sides ± smooth to erose or pitted, (sometimes acute at ends); Great Lakes to New England.||64e.Crataegus ser. Anomalae|