Flora of North America species comparison

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Crataegus rivularis

Crataegus orbicularis

mountain river hawthorn, river hawthorn

hawthorn, round-leaf hawthorn
Habit Shrubs or trees, 30–50 dm. Shrubs, wide-spreading, 20–40 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 sparsely pubescent, 1-year old strong mid brown, older dull gray;

thorns on twigs straight or more often recurved, slender, 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 1.2–2 cm, adaxially short-hairy, usually eglandular;

blade broadly elliptic to suborbiculate, 5–8 cm, thin, base curved in wider blades, ± attenuate in narrower ones, lobes 3 or 4 per side, short-triangular, margins serrate, teeth very small, except near base, veins 5 or 6(or 7) per side, apex ± subacute, abaxial surface glabrate, veins hairy, adaxial short-appressed-hairy.
Inflorescences

6–12-flowered;

branches glandular-punctate;

bracteoles early caducous, usually present, margins sessile-glandular.

10–18-flowered;

branches sparsely villous throughout, sometimes glabrate distally;

bracteole 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.

18 mm diam.;

hypanthium glabrate;

sepals narrowly triangular, 5–6 mm, margins finely glandular-serrate, abaxial pubescence not recorded;

stamens 10, anthers pink;

styles 3 or 4.
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.

in showy infructescences, brick red (mid to late Aug) becoming deep burgundy (Sep), ± oblong, 7–10 mm diam., glabrate;

sepals ± erect, wide, length not recorded;

pyrenes 3 or 4, sides shallowly pitted or almost plane.

Crataegus rivularis

Crataegus orbicularis
Phenology Flowering mid May–early Jun; fruiting Aug–Sep. Flowering May; fruiting Sep–Oct.
Habitat Intermontane streamsides, ditches, flood plains Brush, natural hedgerows
Elevation 1300–2300 m (4300–7500 ft) 300–400 m (1000–1300 ft)
Distribution
from FNA
AZ; CO; ID; NM; NV; UT; WY
[WildflowerSearch map]
[BONAP county map]
from FNA
BC
[BONAP county map]
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 orbicularis is known only from within a few miles of Enderby. The species is readily distinguished from sympatric taxa by the unusual pale yellowish green color of the foliage when young, leaf shape, large flowers, and small glabrous pomes with prominent erect sepals.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 9, p. 510. FNA vol. 9, p. 507.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Purpureofructus
Sibling taxa
C. aemula, C. aestivalis, C. alabamensis, C. alleghaniensis, C. annosa, C. aprica, C. aquacervensis, C. ashei, C. atrovirens, C. attrita, C. austromontana, C. beata, C. berberifolia, C. biltmoreana, C. brachyacantha, C. brainerdii, C. brazoria, C. brittonii, C. buckleyi, C. calpodendron, C. castlegarensis, C. chrysocarpa, C. coccinea, C. coccinioides, C. cognata, C. collina, C. colonica, C. communis, C. compacta, C. condigna, C. craytonii, C. crocea, C. crus-galli, C. cupressocollina, C. delawarensis, C. dispar, C. dodgei, C. douglasii, C. egens, C. egregia, C. enderbyensis, C. erythropoda, C. exilis, C. eximia, C. extraria, C. fecunda, C. flabellata, C. flava, C. florens, C. floridana, C. florifera, C. fluviatilis, C. formosa, C. frugiferens, C. furtiva, C. gattingeri, C. gaylussacia, C. gilva, C. greggiana, C. harbisonii, C. holmesiana, C. ignava, C. incilis, C. integra, C. intricata, C. invicta, C. iracunda, C. irrasa, C. jesupii, C. jonesiae, C. lacrimata, C. laevigata, C. lanata, C. lancei, C. lanuginosa, C. lassa, C. laurentiana, C. leonensis, C. lepida, C. levis, C. lumaria, C. macracantha, C. macrosperma, C. magniflora, C. margarettae, C. marshallii, C. mendosa, C. meridiana, C. mira, C. mollis, C. monogyna, C. munda, C. nananixonii, C. neobushii, C. nitida, C. oakesiana, C. okanaganensis, C. okennonii, C. opaca, C. opima, C. orbicularis, C. ouachitensis, C. padifolia, C. pennsylvanica, C. persimilis, C. pexa, C. phaenopyrum, C. phippsii, C. pinetorum, C. populnea, C. prona, C. pruinosa, C. pulcherrima, C. punctata, C. purpurella, C. quaesita, C. reverchonii, C. rivuloadamensis, C. rivulopugnensis, C. roribacca, C. rubella, C. rubribracteolata, C. saligna, C. sargentii, C. scabrida, C. schizophylla, C. schuettei, C. segnis, C. senta, C. sheila-phippsiae, C. sheridana, C. shuswapensis, C. sororia, C. spathulata, C. spes-aestatum, C. stolonifera, C. stonei, C. submollis, C. suborbiculata, C. succulenta, C. tecta, C. teres, C. texana, C. tracyi, C. triflora, C. turnerorum, C. uniflora, C. ursopedensis, C. venusta, C. viridis, C. visenda, C. wattiana, C. williamsii, C. wootoniana, C. ×atrorubens, C. ×bicknellii, C. ×coleae, C. ×collicola, C. ×disperma, C. ×dispessa, C. ×fretalis, C. ×incaedua, C. ×kelloggii, C. ×latebrosa, C. ×lucorum, C. ×rufula, C. ×sicca, C. ×vailiae
C. aemula, C. aestivalis, C. alabamensis, C. alleghaniensis, C. annosa, C. aprica, C. aquacervensis, C. ashei, C. atrovirens, C. attrita, C. austromontana, C. beata, C. berberifolia, C. biltmoreana, C. brachyacantha, C. brainerdii, C. brazoria, C. brittonii, C. buckleyi, C. calpodendron, C. castlegarensis, C. chrysocarpa, C. coccinea, C. coccinioides, C. cognata, C. collina, C. colonica, C. communis, C. compacta, C. condigna, C. craytonii, C. crocea, C. crus-galli, C. cupressocollina, C. delawarensis, C. dispar, C. dodgei, C. douglasii, C. egens, C. egregia, C. enderbyensis, C. erythropoda, C. exilis, C. eximia, C. extraria, C. fecunda, C. flabellata, C. flava, C. florens, C. floridana, C. florifera, C. fluviatilis, C. formosa, C. frugiferens, C. furtiva, C. gattingeri, C. gaylussacia, C. gilva, C. greggiana, C. harbisonii, C. holmesiana, C. ignava, C. incilis, C. integra, C. intricata, C. invicta, C. iracunda, C. irrasa, C. jesupii, C. jonesiae, C. lacrimata, C. laevigata, C. lanata, C. lancei, C. lanuginosa, C. lassa, C. laurentiana, C. leonensis, C. lepida, C. levis, C. lumaria, C. macracantha, C. macrosperma, C. magniflora, C. margarettae, C. marshallii, C. mendosa, C. meridiana, C. mira, C. mollis, C. monogyna, C. munda, C. nananixonii, C. neobushii, C. nitida, C. oakesiana, C. okanaganensis, C. okennonii, C. opaca, C. opima, C. ouachitensis, C. padifolia, C. pennsylvanica, C. persimilis, C. pexa, C. phaenopyrum, C. phippsii, C. pinetorum, C. populnea, C. prona, C. pruinosa, C. pulcherrima, C. punctata, C. purpurella, C. quaesita, C. reverchonii, C. rivularis, C. rivuloadamensis, C. rivulopugnensis, C. roribacca, C. rubella, C. rubribracteolata, C. saligna, C. sargentii, C. scabrida, C. schizophylla, C. schuettei, C. segnis, C. senta, C. sheila-phippsiae, C. sheridana, C. shuswapensis, C. sororia, C. spathulata, C. spes-aestatum, C. stolonifera, C. stonei, C. submollis, C. suborbiculata, C. succulenta, C. tecta, C. teres, C. texana, C. tracyi, C. triflora, C. turnerorum, C. uniflora, C. ursopedensis, C. venusta, C. viridis, C. visenda, C. wattiana, C. williamsii, C. wootoniana, C. ×atrorubens, C. ×bicknellii, C. ×coleae, C. ×collicola, C. ×disperma, C. ×dispessa, C. ×fretalis, C. ×incaedua, C. ×kelloggii, C. ×latebrosa, C. ×lucorum, C. ×rufula, C. ×sicca, C. ×vailiae
Name authority Nuttall: in J. Torrey and A. Gray, Fl. N. Amer. 1: 464. (1840) J. B. Phipps & O’Kennon: Sida 20: 138, fig. 9. (2002)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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