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aubépine flabelliforme, fan-leaf hawthorn

river hawthorn

Habit Shrubs or trees, 40–50 dm. Shrubs or trees, multi-stemmed, 30–40(–70) dm.
Stems

twigs: new growth reddish at first, usually sparsely pubescent, 1-year old deep chestnut brown, older dull gray;

thorns on twigs 1-year old shiny, dark brown, stout to slender, 4–6 cm.

twigs: new growth golden green to strongly reddish tinged, sparsely pubescent or glabrous, 1-year old usually shiny, dark brown, older gray;

thorns on twigs 1-year old shiny, deep brown to blackish, often black-tipped, stout to slender, 2.5–5 cm.

Leaves

petiole 1–2 mm wide, length 40–50% blade, glandular;

blade glossy, dark green, broadly elliptic to ovate, 4–7 cm, base cuneate to slightly rounded, lobes 4 or 5 per side, sinuses deep, lobe apex acuminate, margins sharply serrate, teeth gland-tipped, veins 5 or 6 per side, apex acute, abaxial surface glabrous except along veins, adaxial densely appressed-scabrous young, glabrescent.

petiole length 30–60% blade, sparsely to densely glandular;

blade ovate, 3–6 cm, base subcordate, truncate, or rounded to cuneate, lobes 3–6 per side, sinuses shallow to moderately deep, lobe apex acute to acuminate, margins serrate, teeth numerous, small, larger ones conspicuously glandular, particularly at base, smaller ones inconspicuously gland-tipped, veins 4–6 per side, apex acute, adaxial surface densely appressed-scabrous-pubescent young, glabrescent.

Inflorescences

5–10-flowered;

branches villous;

bracteole frequency not recorded, linear.

5–12-flowered;

branches pubescent;

bracteoles usually absent (even young), sometimes few to several, often red-tinged, ± linear.

Flowers

13–17 mm diam.;

hypanthium glabrous or villous at base;

sepals 4–5 mm, margins entire, glandular to glandular-serrate, rarely nearly eglandular, apex acute, abaxial pubescence not recorded;

stamens 5–10 or 20, anthers usually pink;

styles 3–5.

12–17 mm diam.;

hypanthium glabrous;

sepals 4–5 mm, margins subentire to weakly serrate, usually eglandular, abaxially glabrous or pubescent;

stamens 5–10, anthers pink to reddish purple;

styles 3–5.

Pomes

crimson, ± ellipsoid, 8–10 mm diam., sometimes ± pruinose;

sepals spreading or usually erose, not or obscurely elevated;

pyrenes 3–5, dorsally deeply grooved.

bright to deep red, suborbicular to ellipsoid, 8–15 mm diam.;

sepals erose or erect-patent;

pyrenes 3–5, dorsally shallowly grooved.

2n

= 51.

Crataegus flabellata

Crataegus fluviatilis

Phenology Flowering May–Jun; fruiting Sep–Oct. Flowering May–Jun; fruiting Sep–Oct.
Habitat Brush, successional fields, fencelines, woodland edges, open woodlands Old fields, fencerows, brush, woodland margins, open woods
Elevation 10–200 m (0–700 ft) 0–500 m (0–1600 ft)
Distribution
from FNA
CT; MA; ME; NH; NY; VT; NB; NS; ON; QC
[WildflowerSearch map]
from FNA
CT; IL; MA; ME; MI; MN; NH; NY; RI; VT; WI; ON; QC
Discussion

Crataegus flabellata occurs along the Niagara Escarpment in Ontario, on both sides of Lake Ontario and the St. Lawrence, to New Brunswick and Nova Scotia, and to Massachusetts. Reports for Newfoundland have not been substantiated.

Crataegus flabellata is distinctive with its leaf blades glossy dark green, ovate to broadly elliptic, cuneate at the base, and with deep acuminate lobes. Specimens with less glandularity or serration of the sepal margins may resemble C. fluviatilis. In spite of the obvious differences in morphology and range, C. flabellata and C. macrosperma often have been combined by floristicians. From C. chrysocarpa, C. flabellata is distinguished by its shinier, ellipsoid, glabrous fruit, by the usually deeper, acuminate lobes of its glossy, dark green leaves, and by longer, slightly more acute sepals. Typically, the inflorescences and hypanthia of eastern C. chrysocarpa are densely hairy, practically tomentose, unlike C. flabellata with its more sparsely hairy pedicels and glabrous distal hypanthia. It is conceivable that, due to morphological intermediacy and the sympatry of all three species within the range of C. flabellata, this species represents the result of ancient hybridization between C. chrysocarpa and C. macrosperma.

Crataegus flabellata is usually divided into two varieties: var. flabellata (10 stamens) and var. grayana (20 stamens), the latter being particularly common in southern Quebec. There appears to be little, if any, other constant differentiating feature. Crataegus crudelis, also from Quebec, is a form recognized by long thorns (to 10 cm).

The name Crataegus densiflora Sargent, which pertains to C. flabellata, is illegitimate.

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

Crataegus fluviatilis includes a range of intermediates between C. flabellata and C. macrosperma. There are three main forms. In the typical form, sporadic in Quebec and New England, the glandular-serration of the sepal margins is less pronounced and the inflorescence branches at anthesis are less densely hairy than in C. flabellata, but the leaves are more similar to those of C. macrosperma. They could represent rare hybrid derivatives of these two species. In the central Great Lakes region (Illinois to Ontario), more frequent forms occur attributable to C. apiomorpha, similar to sympatric C. macrosperma, differing mainly in their soft-hairy inflorescences. More complex variation occurs in Minnesota, where forms with densely pubescent inflorescences occur in local populations, often intermixed with otherwise identical C. macrosperma (glabrous inflorescences). Both the latter are notable for their serrate sepal margins, not the norm for C. macrosperma. Into the mix are identical forms with 20 stamens, which perhaps are C. asperata Sargent. This Minnesota complex is notable for smallish leaves (4–6 cm), is constant for characters other than those mentioned above, and suggests active introgression.

Confusion between the Minnesota form of Crataegus fluviatilis and sympatric C. chrysocarpa might be possible; a helpful field character at anthesis is the pink anthers of the former; at other times, it is the flexible petioles that allow the leaves of C. fluviatilis to flutter in the wind, unlike those of C. chrysocarpa, which have stiffer petioles.

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

Source FNA vol. 9, p. 567. FNA vol. 9, p. 564.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Tenuifoliae Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Tenuifoliae
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. 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. 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. 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. 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
Synonyms Mespilus flabellata, C. crudelis, C. flabellata var. densiflora, C. flabellata var. grayana, C. grayana C. apiomorpha
Name authority (Bosc ex Spach) K. Koch: Verh. Vereins Beförd. Gartenbaues Königl. Preuss. Staaten, ser. 2, 1: 240. (1853) Sargent: Rhodora 5: 117. (1903)
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