Crataegus (sect. Coccineae) ser. Pruinosae

Shrubs or trees, (20–)30–80 dm, main trunk dominant. Stems: trunk bark gray-brown, flattened-scaly, freshly exposed bark often orange-brown; branches spreading; twigs ± straight, new growth glabrous, 1-year old usually purple-brown, sometimes tan or reddish brown, 2-years old grayish; thorns on twigs usually numerous, straight to recurved, 2-years old usually black or blackish, shiny, sometimes reddish brown or purple, ± fine to slender or moderately thick, 1.5–5 cm. Leaves: petiole length (28–)50–100% blade, glabrous, usually glandular, sometimes eglandular; blade mid to dark green or ± blue-green, ± ovate or ± trullate to rhombic or deltate, sometimes suborbiculate, (2–)3–6(–7) cm, thin to subcoriaceous, base cuneate to truncate, sometimes cordate or rounded, lobes (1–)3 or 4 per side, sinuses shallow to moderately deep, lobe apex ± acute, sometimes ± obtuse, margins finely to coarsely serrate, venation craspedodromous, veins 4–7 per side, apex acute to obtuse, surfaces usually glabrous, sometimes adaxial sparsely hairy young. Inflorescences 4–10-flowered, convex panicles; branches usually glabrous, sometimes sparsely villous; bracteoles caducous, few to numerous, rarely absent, linear, membranous, margins sessile- or short-stipitate-glandular. Flowers 15–30 mm diam.; hypanthium glabrous; sepals triangular, length 1/2 petal, margins usually subentire, sometimes entire, rarely glandular-serrate; stamens (10) 20, anthers white to pink or red, sometimes cream; styles 3–5. Pomes pink, mauve, or pale green, sometimes scarlet, deep crimson, or purple, suborbicular, (6–)7–15(–20) mm diam., strongly pruinose, glabrous; flesh hard (until overripe); sepals usually on prominent collar, spreading, non-accrescent; pyrenes (2 or)3–5, often angular.

Distribution

c, e North America.

Discussion

Species 6 (6 in the flora).

Members of ser. Pruinosae are common from Wisconsin through the southern Great Lakes to southern Quebec and southern New England, to Arkansas and Louisiana to Georgia but absent from the southern coastal plain. In the north, they are found mainly in the open; southward they are more often found in woodland shade.

The core of ser. Pruinosae is a natural group of very thorny hawthorns with glabrous, somewhat blue-green, medium-sized to fairly large leaves, mid season anthesis relative to congeners, usually entire sepal margins, and hard, pruinose, often pink or mauve pomes, most with strikingly elevated fruiting calyx. All taxa except Crataegus pruinosa var. dissona have 20 stamens. Crataegus pruinosa var. virella, with the adaxial surface of younger leaves scabrous, might key to ser. Tenuifoliae when in flower. Crataegus gattingeri resembles C. iracunda (ser. Tenuifoliae) in fruit, though differing in leaf adaxial surface indumentum, leaf shape, stamen number, and anther size (see discussion below and under 58. C. iracunda). Members of ser. Pruinosae are similar to members of ser. Intricatae in many particulars, including range; they differ in bracteole form, fruit color, and leaf indumentum and often in stamen number.

The interserial hybrid Crataegus ×coleae keys out in the sixth couplet.

Selected References

Sinnott, Q. P. and J. B. Phipps. 1983. Variation patterns in Crataegus series Pruinosae (Rosaceae) in southern Ontario. Syst. Bot. 8: 59–70.

Lower Taxa

Crataegus cognata, Crataegus compacta, Crataegus formosa, Crataegus gattingeri, Crataegus pruinosa, Crataegus suborbiculata

Key

1	Anthers 0.3–0.4 mm	> 2
1	Anthers 0.6–0.8 mm	> 3
2	Leaf blades trullate to rhombic-ovate, sinuses shallow, lobe apices subacute, bases cuneate, marginal teeth 1 mm.	Crataegus compacta
2	Leaf blades ± deltate to narrowly ovate, sinuses shallow, lobe apices acute, bases rounded to broadly cuneate, marginal teeth 2 mm.	Crataegus gattingeri
3	Leaf blades deltate, broadly elliptic, rhombic, or suborbiculate (widest near middle)	> 4
3	Leaf blades ± ovate to oval, trullate, or broadly rhombic-elliptic (widest in basal 1/3)	> 5
4	Anthers cream, pink, or red; flowers 20–24 mm diam.	Crataegus suborbiculata
4	Anthers white; flowers 22–30 mm diam.	Crataegus formosa
5	Anthers white.	Crataegus cognata
5	Anthers pink to bright rose or dull purple, sometimes cream	> 6
6	Pomes greenish with pink or mauve areas, sometimes bright crimson or scarlet, highly pruinose, not punctate; pyrene sides plane.	Crataegus pruinosa
6	Pomes bright orange-red, at most slightly pruinose, punctate; pyrene sides each linearly scarred.	Crataegus ×coleae