Crataegus rivularis |
Crataegus roribacca |
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mountain river hawthorn, river hawthorn |
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Habit | Shrubs or trees, 30–50 dm. | Trees, 40–70 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. |
trunk bark dark gray, thin, scaly; twigs: new growth not recorded, 1-year old mid brown, ± glossy, older dark gray; thorns on twigs few, 1-year old color not recorded, 3–5 cm. |
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 length 50–60% blade, glandularity not recorded; blade ovate to broadly elliptic (suborbiculate or broadly deltate on extension shoots), 4–5.5 cm (larger on extension shoots), base broadly cuneate to truncate (truncate to cordate on extension shoots), lobes 0, or 3 or 4 per side, sinuses shallow, lobes often mere apiculi, margins serrate, teeth 1.5–3 mm, veins 6 or 7 per side, apex acuminate, adaxial surface densely crisp-pubescent young, glabrescent. |
Inflorescences | 6–12-flowered; branches glandular-punctate; bracteoles early caducous, usually present, margins sessile-glandular. |
8–20-flowered; branches glabrous; bracteoles few, linear. |
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. |
13–15 mm diam., hypanthium glabrous; sepal length not recorded, margins entire, abaxially glabrous; stamens 20, anthers purple; styles 3. |
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. |
dark red, sometimes with orange or orange-red spots, broadly pyriform, 14–17 mm diam., smooth; flesh pale yellow; sepals recurved; pyrenes 3, dorsally deeply grooved. |
Crataegus rivularis |
Crataegus roribacca |
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Phenology | Flowering mid May–early Jun; fruiting Aug–Sep. | Flowering Apr; fruiting Sep. |
Habitat | Intermontane streamsides, ditches, flood plains | Habitat not recorded |
Elevation | 1300–2300 m (4300–7500 ft) | 600–700 m (2000–2300 ft) |
Distribution |
AZ; CO; ID; NM; NV; UT; WY
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NC |
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.) |
Of conservation concern. Crataegus roribacca was found by Ashe in Swain County; no recent collection is known. The specimen studied (CM 289601) is in excellent condition and has all the hallmarks of ser. Tenuifoliae, although E. J. Palmer (1925) left it unassigned. The leaf differs from those of other members of the series in shape and size of marginal teeth, and from most in vein number. Crataegus roribacca does not seem to be a hybrid, so it is perhaps only an unusual form of C. schuettei. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 510. | FNA vol. 9, p. 566. |
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Tenuifoliae |
Sibling taxa | ||
Name authority | Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. (1840) | Ashe: J. Elisha Mitchell Sci. Soc. 17: 4. (1900) |
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