Flora of North America species comparison

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Crataegus uniflora

Crataegus submollis

dwarf hawthorn, one-flower hawthorn

aubépine subsoyeuse, northern downy hawthorn, northern red haw, Quebec hawthorn
Habit Shrubs, 10–20(–50) dm. Shrubs, sometimes trees, 60–70 dm.
Stems

twigs: new growth densely appressed-pubescent, 1-year old brown, older grayish;

thorns on twigs usually numerous, sometimes absent, ± straight, 1-year old black, needlelike, 3–5(–8) cm;

young thorns soft, rapidly growing, needle-pointed shoots with linear bracts, often curved initially, straightening.

twigs: new growth appressed-pubescent, 1-year old tan to brown, older gray;

thorns on twigs usually numerous, straight to curved, 2-years old shiny blackish, ± thick, 4–7 cm.
Leaves

petiole very short or absent, pubescent, glandular or not;

blade narrowly elliptic, elliptic, obtrullate, spatulate, oblanceolate, or narrowly rhombic-elliptic, sometimes suborbiculate, (1–)1.5–3(–6) cm, length/width = 1.5 or narrower, base cuneate, lobes 0, margins crenate to serrate, teeth variably caducous, black eglandular or gland-tipped, venation semicamptodromous to camptodromous, veins 3 or 4(or 5) per side, ± impressed, apex obtuse to broadly acute, often somewhat glossy, abaxial surface sparsely to moderately pubescent, veins ± densely pubescent, adaxial densely scabrous, especially young.

petiole length 30–50% blade, densely pubescent, ± glandular, glands black;

blade ± broadly ovate to rhombic-elliptic, 4–9(–11) cm, chartaceous, base cuneate to almost truncate, lobes 3–5 per side, obscure on smaller leaves, sinuses shallow to moderately deep, lobe apex acuminate, margins sharply, doubly serrate, on larger leaves teeth 2–3 mm, gland-tipped at least initially, veins 5–7 per side, apex acute to subobtuse, abaxial surface sparsely appressed-pubescent, sometimes glabrescent, veins abaxially pubescent, adaxial densely scabrous-pubescent young, variably glabrescent.
Inflorescences

1–3(–5)-flowered;

branches pubescent;

bracteoles of two types: ± persistent, green, herbaceous, margins serrate, teeth glandular, or caducous, linear, membranous to herbaceous, margins glandular.

5–15-flowered;

branches densely pubescent;

bracteoles caducous, linear, membranous, margins sessile-glandular, larger similar but late-deciduous, more herbaceous.
Flowers

10–15 mm diam.;

hypanthium strongly tomentose, (sometimes bearing a caducous, linear, membranous to herbaceous, gland-margined bracteole);

sepals foliaceous, usually longer than petals, 2–4 mm wide, surfaces sparsely pubescent;

anthers white to cream;

styles 5.

20–22 mm diam.;

hypanthium tomentose;

sepals narrowly triangular, 6–7 mm, margins deeply glandular-serrate, abaxially pubescent;

stamens 10(or 20), anthers ivory;

styles (3–)5.
Pomes

yellowish to ruddy, 8–10(–12) mm diam., ± tomentose;

flesh firm, dry, or mealy;

sepals persistent, patent, 7 mm;

pyrenes 4 or 5.

bright red, suborbicular to pyriform or ellipsoid, 10–15 mm diam., hairy, especially proximally and distally;

sepals prominent, erect-patent, stiff;

pyrenes 3–5.
2n

= 51, 68.

= 68.

Crataegus uniflora

Crataegus submollis
Phenology Flowering Apr–May; fruiting Sep–Oct. Flowering May–Jun; fruiting Sep–Oct.
Habitat Sand barrens, sandhills, open scrubby woodlands, often associated with Pinus clausa, P. palustris, P. rigida and xerophytic species of Quercus and Carya Brush, natural hedgerows, field margins, apparently calciphile
Elevation 10–200 m (0–700 ft) 20–400 m (100–1300 ft)
Distribution
from FNA
AL; AR; DE; FL; GA; IL; IN; KY; LA; MD; MO; MS; NC; NJ; NY; OH; OK; PA; SC; TN; TX; VA; WV; Mexico (Tamaulipas)
[WildflowerSearch map]
[BONAP county map]
from FNA
MA; ME; MI; NH; NY; OH; PA; VT; WI; NB; NS; ON; QC [Introduced in Europe]
[WildflowerSearch map]
[BONAP county map]
Discussion

Crataegus uniflora is widespread in the southeastern United States from Long Island (New York) to eastern Texas; it is most abundant in the coastal plain and lower piedmont. A disjunction in the Mississippi embayment between trans-Mississippian and cis-Mississipian populations mirrors a similar pattern in C. spathulata (J. B. Phipps 1998).

Crataegus uniflora is usually easy to identify because of its small size, leaves small and coriaceous with lobes absent, numerous straight, fine thorns, inflorescences uniflorous or few-flowered, sepals glandular-pectinate and equal to or longer than the petals, anthers white to cream, and pomes yellowish to ruddy. Possible confusion with some members of ser. Lacrimatae is treated under the series discussion. Sterile plants might be confused with small, sterile ones of C. berberifolia (ser. Crus-galli) except for the smaller number of lateral veins on the leaves. An interesting feature of C. uniflora is the occasional deep lobing of extension-shoot leaves, even narrow ones, with veins to sinuses.

Crataegus uniflora is somewhat variable in plant size, leaf shape, number of flowers to an inflorescence (though commonly one), and anther color (usually ivory to cream). The typical form, which is common, has 1- or 2-flowered inflorescences, and is usually a small shrub with more or less spatulate to narrowly obovate leaves. Some particularly dwarf forms of this, on laterite soil in Georgia, have been observed with over 100 flowers when less than 3 dm.

Forms of Crataegus uniflora with 3–6-flowered inflorescences are also common and are represented by C. parvifolia and C. trianthophora. These are connected to the typical uniflorous kind by numerous intermediates and may be distinguished from the related C. brittonii by their smaller and narrower leaves with lobes absent.

Three anomalous variants, very similar or identical to Crataegus uniflora except for possessing small, more or less unlobed but glandular-serrate sepals, are known. These are: C. croomiana Sargent from northern Florida, C. bisulcata Ashe from North Carolina, and C. grossiserrata Ashe from Florida. The first, also best known, is further distinguished by pink anthers, the second by broader leaves, and the third by often orbiculate (unusual for ser. Parvifoliae) extension-shoot leaves with a tendency to deep lobing sometimes with veins to sinuses, and particularly strong and sharp leaf teeth. All suggest hybrid origin with ser. Lacrimatae.

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

Crataegus submollis ranges from eastern Wisconsin and northern Michigan through the limestone areas of southern Ontario into Quebec, and New York to Maine and southern Nova Scotia. It is occasionally found in Pennsylvania and is plausible for northern West Virginia. It is allopatric with C. mollis. Crataegus submollis has also been recorded wild in Europe, including France and northern Italy.

Crataegus submollis, though quite similar to C. mollis, differs in its distribution, stature, petiole glandularity, stamen number, and greater thorniness.

The typical form of Crataegus submollis has proportionately broader leaves that are broadly cuneate to subcordate basally. By contrast, C. champlainensis is a form with proportionately narrower leaves more or less truncate to subcordate at the base. Intermediate forms are common in Quebec and New England. Placing the 20-stamen C. canadensis, a distinctive local form from the Montreal area, with C. submollis is based on leaf shape, glandular petioles, and disjunction from the range of C. mollis. Crataegus arnoldiana is a form with particularly large fruit.

Possession of glandular petioles and similar flowering time means that Crataegus submollis can sometimes show surprising similarity to large specimens of C. chrysocarpa. Then, the large fruiting calyces and the tendency to a more herbaceous larger bracteole type of C. submollis, typical for ser. Molles, differentiate.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 9, p. 606. FNA vol. 9, p. 556.
Parent taxa Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Parvifoliae Rosaceae > subfam. Amygdaloideae > tribe Maleae > Crataegus > sect. Coccineae > ser. Molles
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. 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. 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. shuswapensis, C. sororia, C. spathulata, C. spes-aestatum, C. stolonifera, C. stonei, 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 C. parvifolia, C. trianthophora C. arnoldiana, C. canadensis, C. champlainensis
Name authority Münchhausen: Hausvater 5: 147. (1770) Sargent: Bot. Gaz. 31: 7. (1901)
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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