Crataegus rivularis |
Crataegus ×coleae |
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mountain river hawthorn, river hawthorn |
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Habit | Shrubs or trees, 30–50 dm. | Shrubs, 40–50 dm, broad. |
Stems | twigs: new growth greenish, sparsely pubescent, early glabrescent, 1–2-years old often red-purple; bark on younger 2–5 cm thick branches dark gray-brown, sometimes copper-colored; thorns on twigs straight or ± recurved, 2-years old black or purple-black, glossy, fine, 1.5–4 cm. |
trunks numerous, spreading, stout, bark close dark; twigs nearly straight or slightly flexuous, slender, new growth light yellow-green, glabrous, marked by oblong pale lenticels, at end of 1st year bright red-brown, very lustrous, 1-year old dark gray-brown; thorns on twigs numerous, straight, stout, 2.5–4.5 cm, lustrous, often retrorse. |
Leaves | petiole 1–2.5 cm, glabrous; blade elliptic to narrowly elliptic, 3–8 cm, length 2+ times width, thin, base cuneate, lobes 0 or small apiculi at ends of some vein tips, margins serrate, teeth numerous, usually acute, fine to coarse, venation semicamptodromous, veins 4 or 5 per side, larger often branched proximal to ends, apex acute, abaxial surface glabrous, adaxial appressed-strigose young. |
petiole nearly terete, slender, 1.2–1.5 cm; blade ovate to oval, 4.5–5 × 3–3.5 cm, base broadly cuneate, lobes 4 or 5 per side, sinuses shallow, margins sharply serrate, teeth minutely, glandular, glands dark, venation craspedodromous, veins 5 per side, apex acute, abaxial surface pale, adaxial dark green, lustrous, glabrate young, glabrescent. |
Inflorescences | 6–12-flowered; branches glandular-punctate; bracteoles early caducous, usually present, margins sessile-glandular. |
8–12-flowered; branches glabrous; bracteoles caducous, linear, membranous, margins sessile- or stipitate-glandular. |
Flowers | 14–17 mm diam.; sepals broadly deltate, 6–8 mm, margins entire, apex narrow, glabrous; stamens 10, anthers pink, sometimes ivory; styles 3–5. |
18–20 mm diam.; hypanthium glabrous; sepals narrowly triangular, margins glandular-serrate; stamens 20, anthers pink, 0.6–0.8 mm; styles 2–4(or 5). |
Pomes | deep red (mid Aug), black or blackish purple mature, suborbicular, 10 mm diam.; sepals ± erect to strongly outcurved or ± patent, 2–3 mm; pyrenes 3 or 4, sides eroded. |
bright orange-red, at most slightly pruinose, suborbicular, 8–10 mm diam., punctate, glabrous; sepals reflexed, elevated on collar; pyrenes 2–4(or 5), dorsally grooved, sides each linearly scarred. |
Crataegus rivularis |
Crataegus ×coleae |
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Phenology | Flowering mid May–early Jun; fruiting Aug–Sep. | Flowering May; fruiting late Sep. |
Habitat | Intermontane streamsides, ditches, flood plains | Successional fields, brush |
Elevation | 1300–2300 m (4300–7500 ft) | 200–300 m (700–1000 ft) |
Distribution |
AZ; CO; ID; NM; NV; UT; WY
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MI |
Discussion | Crataegus rivularis is most abundant in intermontane Colorado and Utah and is one of two hawthorns found in Arizona; it is rare in Nevada. There are reports from northwestern Texas (for example, D. S. Correll and M. C. Johnston 1970); they have not been verified. Crataegus rivularis is one of the more common woody species of mesic, valley bottom intermontane habitats. The species flowers early. Crataegus rivularis is superficially similar to the more or less sympatric, less common, C. saligna; it has larger leaves with fewer veins, larger flowers with ten stamens, and larger pomes. It differs from C. erythropoda little other than in leaf shape and ripe fruit color. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Crataegus ×coleae is rare and known from near Grand Rapids from the late 1800s to the 1940s; it is a presumptive interserial hybrid C. pruinosa (ser. Pruinosae) × C. scabrida (ser. Anomalae). The somewhat unstable leaf form and scarred lateral pyrene faces, reminiscent of C. scabrida, and elevated fruiting calyx, 20 stamens, and glabrous parts, reminiscent of C. pruinosa, are good markers. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 510. | FNA vol. 9, p. 636. |
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus |
Sibling taxa | ||
Name authority | Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. (1840) | Crataegus ×coleae Sargent: Trees & Shrubs 1: 7, plate 4. (1902) — as species |
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