Crataegus rivularis

Nuttall in J. Torrey and A. Gray

in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. 1840.

Common names: Mountain river hawthorn
EndemicIllustrated
Treatment appears in FNA Volume 9. Treatment on page 510. Mentioned on page 509.

Shrubs or trees, 30–50 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. 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. Inflorescences 6–12-flowered; branches glandular-punctate; bracteoles early caducous, usually present, margins sessile-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. 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.


Phenology: Flowering mid May–early Jun; fruiting Aug–Sep.
Habitat: Intermontane streamsides, ditches, flood plains
Elevation: 1300–2300 m

Distribution

V9 859-distribution-map.jpg

Ariz., Colo., Idaho, Nev., N.Mex., Utah, Wyo.

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.

Selected References

None.

Lower Taxa

None.

"fine" is not a number.

... more about "Crataegus rivularis"
appressed-strigose +
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
ivory +  and pink +
pink-purple to purple +
James B. Phipps +
Nuttall in J. Torrey and A. Gray +
exfoliating +  and plated +
2 cm20 mm <br />0.02 m <br /> (5 cm50 mm <br />0.05 m <br />) +
compound +  and simple +
opposite +  and alternate +
cuneate +
elliptic +  and narrowly elliptic +
8 cm80 mm <br />0.08 m <br /> (12 cm120 mm <br />0.12 m <br />) +
suborbiculate +, oblanceolate +, obovate +, less rhombic +  and more or less elliptic elliptic-oblong or ovate-rhombic +
3 cm30 mm <br />0.03 m <br /> (8 cm80 mm <br />0.08 m <br />) +
copper-colored +  and dark gray-brown +
glandular-punctate +
adnate +  and distinct +
crowded +, scattered +  and alternate +
Mountain river hawthorn +
Ariz. +, Colo. +, Idaho +, Nev. +, N.Mex. +, Utah +  and Wyo. +
not +  and aggregated +
1300–2300 m +
1.4 cm14 mm <br />0.014 m <br /> (1.7 cm17 mm <br />0.017 m <br />) +
unisexual +  and bisexual +
not +  and aggregated +
not +  and aggregated +
yellow +  and red or purplish +
0.6 cm6 mm <br />0.006 m <br /> (2 cm20 mm <br />0.02 m <br />) +
old +  and new +
glabrescent +  and pubescent +
Intermontane streamsides, ditches, flood plains +
constricted +
0.2 cm2 mm <br />0.002 m <br /> (0.6 cm6 mm <br />0.006 m <br />) +
crassinucellate +
deciduous +
obscure +  and evident +
eglandular +  and craspedodromous +
entire +  and serrate +
entire +, subentire +  and crenate +
inferior +  and superior +
biseriate +  and clustered +
collateral +  and basal +
0.8 cm8 mm <br />0.008 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
elliptic +  and circular +
0 (?) +  and 4 (?) +
free +  and distinct +
post-mature +
1 cm10 mm <br />0.01 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
Flowering mid May–early Jun +  and fruiting Aug–Sep. +
adnate +, free +, connate +  and distinct +
dark gray-brown +  and russet +
exfoliating +  and corrugated +
blackish purple +, black +  and red +
10 cm100 mm <br />0.1 m <br /> (?) +
suborbicular +
in J. Torrey and A. Gray, Fl. N. Amer. +
not arillate +
0.4 cm4 mm <br />0.004 m <br /> (0.8 cm8 mm <br />0.008 m <br />) +
persistent +
free +  and distinct +
patent +  and erect +
outcurved +  and deltate +
0.2 cm2 mm <br />0.002 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
1-50-flowered +  and few-leaved +
Endemic +  and Illustrated +
free +  and distinct +
branched +  and simple +
persistent +
distinct +
exsert +  and lateral +
elongate +
glabrous +  and tomentose +
Crataegus rivularis +
Crataegus (sect. Douglasia) ser. Cerrones +
species +
6 cm60 mm <br />0.06 m <br /> (10 cm100 mm <br />0.1 m <br />) +
purple-black +, black +  and old +
straight +
slender +
1.5 cm15 mm <br />0.015 m <br /> (4 cm40 mm <br />0.04 m <br />) +
craspedodromous +  and gland-tipped +
inconspicuous +
1 +  and few +
straight +
determinate +
5 +  and 4 +
larger +
tree +  and shrub +