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mountain river hawthorn, river hawthorn

shuswap hawthorn

Habit Shrubs or trees, 30–50 dm. Shrubs, 55 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.

1-year old twigs tan to deep brown;

thorns on twigs straight or slightly recurved, very dark brown young, 2–3 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 1.5–2.2 cm, pubescent, sparsely gland-dotted;

blade rhombic, 5–7 cm, lobes 4 per side, sinuses deep, lobe apex acute, margins remotely serrate, venation craspedodromous, veins 4 or 5 per side, apex acute, abaxial surface glabrous, adaxial sparsely appressed-pubescent.

Inflorescences

6–12-flowered;

branches glandular-punctate;

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

12–18-flowered;

branches glabrous;

bracteole margins 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.

15 mm diam.;

hypanthium glabrous;

sepals triangular, 4–5 mm, margins minutely glandular;

stamens 10–18, anthers pale to bright pink or puce;

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.

brick red young, deep purple mature, somewhat glaucous, suborbicular to ± broadly ellipsoid, 12 mm diam., glabrous;

sepals remnants patent-recurved, apex acute;

pyrenes (3 or)4, sides plane to ± concave, grooved, or irregularly scarred.

2n

= 68.

Crataegus rivularis

Crataegus shuswapensis

Phenology Flowering mid May–early Jun; fruiting Aug–Sep. Flowering May; fruiting Sep–Oct.
Habitat Intermontane streamsides, ditches, flood plains Thickets, natural hedgerows, shade of riverine Populus
Elevation 1300–2300 m (4300–7500 ft) 300–500 m (1000–1600 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 shuswapensis is locally common near Enderby in the northern Okanagan and southwestern Shuswap drainage. Flowering plants from Lake County, Montana, are indistinguishable; fruiting plants from these populations have not been collected.

Crataegus shuswapensis is a distinctive member of ser. Douglasianae in the Okanagan because of its relatively long, stout thorns, large, wide, rhombic, and deeply and sharply incised leaf blades, pink, sometimes puce anthers, somewhat low style and pyrene numbers, and fairly large for the series, suborbicular to broadly ellipsoid purple fruit. Also, this species has a greater frequency of plane-sided pyrenes than has been noted in C. douglasii.

Crataegus shuswapensis is unusual in the genus for its unstable stamen number; in its other characteristics, it is more uniform. The majority of specimens that have been assigned to this species have about ten stamens; these are not dissimilar to an extreme form of C. douglasii that is locally common in northwest Montana and has been noted occasionally elsewhere. This latter variant of C. shuswapensis may be a single apomictic race.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 9, p. 510. FNA vol. 9, p. 514.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Cerrones Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Douglasia > ser. Douglasianae
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. 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. 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. 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: 128, fig. 5. (2002)
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