Crataegus (sect. Douglasia) ser. Purpureofructus
Sida 18: 184. 1998.
Shrubs or trees, (20–)30–60(–100) dm. Stems: twigs: new growth glabrous or densely pubescent, 1-year old deep reddish brown, brown, or purple-brown, older gray to dark gray, sometimes orange-brown overlaid with gray; bark on younger 2–5 cm thick branches mainly dark gray-brown, conspicuous horizontal lenticels absent; thorns on twigs straight to recurved, 2 years old dark brown, red-brown, or blackish brown, shiny, slender to stout, 2–5(–7) cm. Leaves: petiole 1–3 cm, glabrous or sparsely hairy young, eglandular or glandular, glands black; blade ± rhombic to elliptic-oblong or ovate-rhombic, sometimes suborbiculate, 3–8 cm, coriaceous or thin, base cuneate to ± rounded, lobes (0 or)1–4 per side, obscure to evident, sinuses shallow to deep, lobe apex acute or ± subacute to ± rounded, margins serrate except at base, teeth with gland-dots, venation craspedodromous, veins (3 or)4–6(or 7) per side, ± impressed in coriaceous-leaved plants, apex usually acute, sometimes subacute or obtuse, abaxial surface glabrous or glabrate, sometimes subglabrous or glabrescent, veins hairy or not, adaxial scabrous-hairy young, sometimes glabrescent. Inflorescences (5–)8–25-flowered; branches usually sparsely villous, sometimes glabrate; bracteoles caducous, linear, membranous, margins glandular, sometimes nearly eglandular. Flowers (10–)12–18(–22) mm diam.; hypanthium glabrous or pubescent; sepals (2.5–)4–7 mm, margins denticulate to finely, sometimes strongly, glandular-serrate; stamens 5 or 10(–20), anthers white to ivory, cream, or pink; styles 2–5. Pomes bright red to purple (late Aug), reddish purple to deep purple, often nearly black (late Sep), ± orbicular to ellipsoid, ellipsoid-urceolate, ± oblong, or ovoid, (7–)8–10(–15) mm diam., sparsely hairy or glabrous; sepals prominent, usually accrescent (except in C. williamsii), erect-patent, sometimes ± reflexed; pyrenes 2–4(or 5), sides plane to deeply pitted.
w North America.
Species 8 (8 in the flora).
Members of ser. Purpureofructus occur from the Okanagan Valley of British Columbia and Washington east to Montana and southern Saskatchewan. Most species are locally common.
Plants of ser. Purpureofructus share characteristics with those of ser. Douglasianae, but the thorns are usually considerably longer, the partly ripe fruit color is more likely to be red, even bright red, in late August, and the fruiting sepals are usually accrescent. Crataegus williamsii is an exception (see comments there). Several species of ser. Purpureofructus have been shown to have alloploid origin between members of ser. Douglasianae and sect. Coccineae or Macracanthae (M. Zarrei and T. A. Dickinson, pers. comm.). In late summer and fall, the usually abundant fruit of ser. Purpureofructus may turn from bright red to deep purple, and the leaves in some manifest brilliant coloring in bronze, burgundy, and yellow.
|1||Pomes usually short-ellipsoid, pale red young, bright red (late Aug), deepening to oxblood red or darker mature, sepals spreading to reflexed, not thickened or enlarged; anthers pink; nw Montana.||Crataegus williamsii|
|1||Pomes ± orbicular to ellipsoid or nearly ovoid, dull reddish, brick red, bright red, or purplish young (mid Aug), bright red to purple (late Aug), deepening to deep burgundy or purple to black mature (Sep), sepals suberect and sometimes incurved to erect-patent, spreading to erect, ± accrescent; anthers pink, white, or ivory; mainly of the Okanagan or Cypress Hills, only C. phippsii extending to nw Montana||> 2|
|2||Leaf blades of a wider form, broadly elliptic to suborbiculate or ovate to broadly deltate-ovate, lobe apices ± subacute or rounded to broadly angled||> 3|
|2||Leaf blades narrowly ovate to elliptic-rhombic or elliptic, or ovate to ovate-rhombic, lobe apices usually acute||> 4|
|3||Leaf blades broadly elliptic to suborbiculate, lobes short-triangular, (pale green at anthesis); inflorescences sparsely villous, sometimes glabrate distally; pomes 7–10 mm diam., ± oblong, brick red (late Aug) becoming deep burgundy (Sep).||Crataegus orbicularis|
|3||Leaf blades broadly elliptic to ovate or broadly deltate-ovate, lobes rounded to broadly angled, (mid green at anthesis); inflorescences densely short-tomentose; pomes 12 mm diam., ± orbicular to broadly ovoid, red to plum purple (Aug) becoming nearly black (Sep).||Crataegus phippsii|
|4||Thorns on twigs usually ± stout, 2–4(–5) cm; leaf blades ± ovate to ovate-rhombic or ± oblong, ± coriaceous; anthers cream or ivory, sometimes very pale pink; sepals in fruit erect-patent to reflexed; pomes bright to deeper red (late Aug) becoming dark purple (Sep)||> 5|
|4||Thorns on twigs usually ± slender, 3–5(–7) cm; leaf blades broadly elliptic to narrowly ovate or trullate-ovate to broadly elliptic-rhombic, thin or coriaceous; anthers pink, sometimes white; sepals in fruit suberect, erect-recurved, or spreading, (herbaceous); pomes deep red to purple (late Aug), deep burgundy to nearly black (Sep)||> 6|
|5||Leaf blades 3.5–6 cm, ± coriaceous, venation ± impressed adaxially, (flattish to strongly concave, mid green until fall).||Crataegus okanaganensis|
|5||Leaf blades 4–8 cm, softly coriaceous, venation impressed adaxially, (flattish to convex, deep green until fall).||Crataegus enderbyensis|
|6||Leaves matte, lobes small, max LII ca. 10%; flowers 10–14 mm diam.; pomes dull; n Okanagan.||Crataegus atrovirens|
|6||Leaves shiny, lobes larger, max LII 15–25%; flowers 15–18 mm diam.; pomes dull or glossy; Cypress Hills and Bear's Paw Mountains||> 7|
|7||Anthers pale pink to pink; bark on 2–5 cm thick branches gray-brown; leaves ± coriaceous, lobe apices acute, max LII 15–25%; pomes glabrate or moderately to densely pubescent, dull.||Crataegus aquacervensis|
|7||Anthers white; bark on 2–5 cm thick branches orange-brown; leaves thin, lobe apices acute to ± rounded, max LII ca. 15%; pomes glabrous, glossy.||Crataegus cupressocollina|