Crataegus rivularis |
Crataegus reverchonii |
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mountain river hawthorn, river hawthorn |
Reverchon hawthorn, Reverchon's hawthorn |
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Habit | Shrubs or trees, 30–50 dm. | Shrubs, 10–30(–80) dm. | ||||||||
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. |
twigs: new growth glabrous, 1-year old dark gray; thorns on twigs slightly reflexed, 2-years old blackish, usually stout, 3–6 cm. |
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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 2–5 mm, length 7–11% blade, glabrous, eglandular; blade (on extension shoots) ± orbiculate to broadly elliptic, (on short shoots) ± orbiculate to broadly oblong-elliptic, 2–6 cm, very coriaceous, base broadly cuneate, lobes 0, margins serrulate in distal 1/2, venation semicamptodromous, veins 5 or 6 per side, apex subacute to obtuse, surfaces sparsely hairy young, glabrescent. |
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Inflorescences | 6–12-flowered; branches glandular-punctate; bracteoles early caducous, usually present, margins sessile-glandular. |
8–15-flowered; branches usually glabrous; bracteoles linear, small, margins short-stipitate-glandular. |
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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. |
8–12 mm diam.; hypanthium glabrous, sometimes slightly pilose; sepals 4 mm, margins subentire, abaxially glabrous; stamens 10–15(–20), anthers cream, rose, or red; styles (2 or)3–5. |
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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. |
red to orange-red, suborbicular, 10 mm diam., glabrous; sepals persistent, patent or reflexed; pyrenes (1–)3–5. |
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Crataegus rivularis |
Crataegus reverchonii |
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Phenology | Flowering mid May–early Jun; fruiting Aug–Sep. | |||||||||
Habitat | Intermontane streamsides, ditches, flood plains | |||||||||
Elevation | 1300–2300 m (4300–7500 ft) | |||||||||
Distribution |
AZ; CO; ID; NM; NV; UT; WY
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AL; AR; DE; GA; KS; LA; MO; MS; OK; TN; TX
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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.) |
Varieties 3 (3 in the flora). Crataegus reverchonii is differentiated from C. crus-galli by a greater number of styles and pyrenes (except for var. mohrii) and extension-shoot leaves that tend to be suborbiculate. Distinction from a small-leaved form of C. crus-galli from the Edwards Plateau, Texas, needs elucidation. Crataegus stevensiana is sometimes separated out as a variety or species; however, the complex, unresolved variation makes this distinction moot at the moment. The principal variation within Crataegus reverchonii is between smaller-statured, smaller-leaved, smaller-fruited, more-styled, xeromorphic plants of the southwest (var. reverchonii), and larger-leaved, large-flowered, fewer-styled plants of the mid latitude, eastern United States (var. palmeri). Variety mohrii is intermediate. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 9, p. 510. | FNA vol. 9, p. 537. | ||||||||
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Crus-galli | ||||||||
Sibling taxa | ||||||||||
Subordinate taxa | ||||||||||
Name authority | Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. (1840) | Sargent: Trees & Shrubs 1: 55, plate 28. (1903) | ||||||||
Web links |