Crataegus rivularis |
Crataegus magniflora |
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mountain river hawthorn, river hawthorn |
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Habit | Shrubs or trees, 30–50 dm. | Shrubs or 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. |
twigs: new growth greenish, glabrous or sparsely hairy; thorns on twigs straight to recurved, usually ± stout, 2–4 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 30–40% blade, nearly glabrate to hairy, glandular or eglandular; blade ovate to deltate-ovate, 6–10 cm, base broadly ± cordate or rounded to truncate, lobe apex acute, margins serrate, sometimes doubly serrate, teeth 2 mm, adaxial usually densely scabrous young. |
Inflorescences | 6–12-flowered; branches glandular-punctate; bracteoles early caducous, usually present, margins sessile-glandular. |
branches sparsely to densely pubescent. |
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. |
hypanthium glabrous or densely pubescent; stamens 20, anthers pink to rose-purple. |
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. |
usually bright red, suborbicular to ± ovoid, 10–14 mm, often sparsely pubescent (especially at ends); sepals ± spreading or missing. |
2n | = 68 (as C. corusca). |
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Crataegus rivularis |
Crataegus magniflora |
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Phenology | Flowering mid May–early Jun; fruiting Aug–Sep. | Flowering May; fruiting Sep–Oct. |
Habitat | Intermontane streamsides, ditches, flood plains | Brush, woodland margins, fencerows, overgrown pastures |
Elevation | 1300–2300 m (4300–7500 ft) | 20–300 m (100–1000 ft) |
Distribution |
AZ; CO; ID; NM; NV; UT; WY
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IL; MA; MI; NY; PA; WI; ON |
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 magniflora ranges through the southern Great Lakes area from Illinois and Wisconsin to Pennsylvania and Massachusetts. Two forms occur, one with a more nearly truncate leaf base, which is more common in Ontario, and a more fulleriana-like form, which is most common westward. The leaf of Crataegus magniflora is most similar to that of C. coccinea var. coccinea but differs in usually being a little larger, often relatively wider (length/width sometimes equal to 1.1), and in the base being more truncate to more or less cordate than is usual in var. coccinea. Crataegus magniflora was often identified as C. corusca Sargent before it was recognized that the latter represented a putative interserial hybrid of ser. Coccineae × ser. Molles origin. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 9, p. 510. | FNA vol. 9, p. 560. |
Parent taxa | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones | Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Coccineae |
Sibling taxa | ||
Synonyms | C. dayana, C. hillii, C. macounii | |
Name authority | Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. (1840) | Sargent: Bot. Gaz. 35: 383. (1903) |
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