Crataegus
Crataegus sect. Coccineae
aubépine, haw, hawthorn, thornapple
usually 1 in larger plants, more in smaller plants, outer spreading;
bark usually checked into rough, exfoliating plates, when usually dark, but freshly exposed ± russet, sometimes deeply corrugated and dark gray-brown, or smooth, thin and exfoliating, when usually pale, rarely with prominent horizontal lenticels;
extension (long) and short shoots present;
compound thorns on trunk abundant or absent;
twigs ± thorny, thorns 10–60(–100) mm, growth determinate (indeterminate in sect. Crataegus); glabrous or tomentose in first year.
trunks 1–several, ± erect to oblique, bark usually flattened-scaly, sometimes corrugated or thin-exfoliating;
compound thorns on trunks present or absent;
thorns on twigs determinate, straight to recurved, slender to stout.
deciduous (sometimes winter-persistent in south), cauline, alternate, scattered on extension shoots, often crowded on short shoots, simple or deeply lobed;
stipules deciduous with leaves or sometimes earlier, free, circinate or falcate, margins serrate to crenate, glandular;
petiole present, often glandular;
blade ± ovate to narrowly elliptic or obovate, (1.2–)2–8(–12) cm, wider leaves shallowly to deeply incised (rarely pinnately compound), the narrower less incised, margins flat, serrate, young teeth often gland-tipped, venation pinnate, usually craspedodromous, surfaces glabrous to tomentose.
blade broadly lanceolate, elliptic, spatulate, obovate, obtrullate, rhombic-ovate, broadly ovate to suborbiculate, 1–8(–12) cm, length 1.6–2 times width, coriaceous to thin, lobes 0 or 1–4 or 5(–9), sinuses usually shallow, sometimes deep, veins 1–8(–10) per side, absent to sinuses, matte.
terminal on few-leaved annual short shoots that usually arise from a subterminal bud on a woody short shoot, rarely arise laterally direct from an extension shoot, 1–50-flowered, panicles domed, monopodial, corymbose, or flowers solitary;
bracts sometimes present, leafy;
bracteoles present, usually caducous.
branches glabrous or pubescent;
symmetric bracteoles present, basal stipuliform, falcate bracteoles absent.
present.
perianth and androecium epigynous, 8–25 mm diam.;
hypanthium ± obconic, constricted at disc except for opening, 2–6 mm wide;
sepals 5, spreading, triangular;
petals 5, white, sometimes pale cream (ser. Montaninsulae) or pale pink (ser. Aestivales, ser. Molles), ± circular, sometimes elliptic (ser. Lacrimatae) or ± elliptic (ser. Apiifoliae, ser. Triflorae), base barely clawed, margins ± entire;
stamens 5–20 (30–45 in C. triflora), usually shorter than petals;
torus absent;
carpels 1–5, distinct, laterally touching, partially adnate to hypanthium, styles 1–5, lateral, distinct, adnate most of length, exsert;
ovules 2, superposed.
post-mature petals pale paper brown;
stamens (5–)10 or 20(–47), rarely ca. 15, anthers pink to purple or white to cream.
pomes, yellow to red or purplish to black mature, suborbicular to ellipsoid or pyriform, 6–20(–25) mm diam. (larger in some cultivars), flesh soft, sometimes hard;
hypanthium persistent;
sepals often persistent, appressed to erect;
carpels woody;
styles usually persistent.
usually red, sometimes yellow, orange, or pink mauve, sometimes remaining green until late, or green-blotched, sometimes ± conspicuously pruinose;
pyrene sides plane (to shallowly concave in C. ursopedensis).
1–5, dorsally grooved, sides plane or eroded, excavated, or pitted.
= 17.
Crataegus
Crataegus sect. Coccineae
Species ca. 230 (169, including 17 hybrids, in the flora).
Species of Crataegus vary from heliophiles to moderately shade tolerant. Most hawthorns are mesophytes and soil moisture regime appears to be a more important habitat determinant than soil type. Hawthorns are mostly found on topland, mesic, fine-textured soils, usually reflective of a reasonable rainfall. None are strict calciphiles or acidophiles. In drier parts of the Great Plains and intermontane regions, suitable habitats are often restricted to the vicinity of watercourses, or marsh edges, seeps, ditches, etc. Relatively few taxa grow in a drier (for example, ser. Lacrimatae) or moister (ser. Aestivales) soils than the norm.
Often abundant, hawthorns can be important components of some ecosystems, acting as sources of shelter and protection for animal life, nesting habitat, source of food (pomes), mainly for medium-sized passerine birds, and source of nectar and pollen. Hawthorns may be nurse plants to deciduous trees and play an important role in succession. Gymnosporangium R. Hedwig rusts may be serious pests on hawthorns where junipers are common. Other, locally serious, threats to native hawthorns include aggressive introduced woody competitors such as Lonicera japonica Thunberg in the southeast and Rhamnus cathartica Linnaeus in the northeast (P. M. Catling and G. Mitrow 2012b).
Hawthorns flower in spring during (rarely before) leaf expansion. They are mass-flowerers such that the anthesis season for a single plant lasts seven to ten days, the timing principally dependent on accumulated heat. Phenological separation is an important evolutionary driver and makes knowledge of flowering sequence very helpful in identification. The length of local flowering season may be as long as six weeks in localities with multiple hawthorns. Pollination is primarily by Diptera and Hymenoptera (N. Power 1980).
Seven species, including Crataegus azarolus Linnaeus, C. mexicana Moçiño & Sessé ex de Candolle, C. pinnatifida Bunge, and C. scabrifolia (Franchet) Rehder as well as those of ser. Aestivales of the flora area, are minor commercial fruit crops. Hawthorn extracts are used to treat hypertension in alternative medicine. In addition to hawthorn, the names haw, thorn, and thorn apple are used colloquially (see J. B. Phipps et al. 2003).
Three ploidy levels (2x, 3x, and 4x) have been demonstrated in a wide range of North American hawthorns both cytologically (various authors) and by flow cytometry (N. Talent and T. A. Dickinson 2005). Diploids are usually sexual outbreeders; triploids are obligate apomicts; tetraploids are self-compatible facultative apomicts; and apomicts are pseudogamous. The polyploid groups are most difficult taxonomically.
Hybridization is routinely touted as a principal cause of taxonomic difficulty in Crataegus. Hybridization within series may be widespread but is hard to detect; the group led by T. A. Dickinson detailed work on it using the C. douglasii complex (for example, E. Y. Y. Lo et al. 2010) is groundbreaking. Putative hybrids between species in different series, often resulting in plants receiving hybrid species rank, are easier to suspect and have been proposed in numerous instances, but on investigation nearly all cases proved non-persistent and only rarely recreated (J. B. Phipps 2005). Series Anomalae, which has some widespread and not uncommon species, may be one exception. Hybrids between species in different sections are nearly unknown today in North America, except for hybrid swarms between the introduced sexual compilospecies C. monogyna and a couple of native diploids (R. Love and M. Feigen 1979; T. C. Wells and Phipps 1989). Ancient, wide hybridization is proposed for the origin of three common, taxonomically isolated, southeastern species (Lo et al. 2009). Hybridization, as contributing to taxonomic difficulty, appears to be restricted to situations involving closely related species or within particular species-complexes.
This treatment of Crataegus is the first attempted for the whole flora area since the work of J. Torrey and A. Gray (1838–1843). It is mainly conservatively based on E. J. Palmer (1950, 1952, 1960), except for series Apricae and Lacrimatae, and new species, mainly western, not known to Palmer.
The taxonomic complexity of North American Crataegus has resulted in extremely narrow species (C. S. Sargent, etc.), middling species (E. J. Palmer), and very broad ones (A. Cronquist). Here, a morphological species concept (MSC) is used. In general, middling positions are favored, and the number of species treated proves similar to what might be extrapolated from work by Palmer except for some southeastern series and western taxa unknown to Palmer. As used here, the MSC assumes that distinguishing suites of character states are adaptive.
A principal objective of this treatment has been to draw attention to the often great, but little discussed, infraspecific variation. This has been possible due to extensive fieldwork by the author and large quantities of available herbarium material. Because of evolutionary implications, infraspecific variation is given considerable attention. Levels of variation in some cases exceed those of woody sexual species of comparable abundance and range yet may not lead to clear dissection into several less variable species. Where high levels of variation occur, varieties are not necessarily recognized, either due to insufficient study or simply because the variation appears chaotic. For example, in the broadly treated Crataegus macrosperma, the infrataxa earlier recognized are not formally treated herein, but detailed discussion of variation is provided. When varieties are used, these themselves may also be variable, as with C. pruinosa and C. viridis. An interesting feature revealed for North American Crataegus is the frequency of occurrence of sympatry in infraspecific variation, this also shown by E. Y. Y. Lo et al. (2009b) in an in-depth study of the C. douglasii complex.
A frequent difficulty for North American Crataegus derives from the co-existence of sympatric, significantly atypical, named entities with otherwise well-defined taxa. They are often uncommon, might be hybrid or simply particularly divergent forms; usually, no one knows. Treatment could be as species (greatly inflating the text), as synonyms (which seems misleading), or dismissed from the flora altogether (which would cripple proper understanding of North American Crataegus variation). Here, they are diagnosed very briefly in the discussion of the most relevant taxon.
Higher level variation is arranged into six sections, these divided into 32 series, mostly following the circumscriptions of E. J. Palmer (1925). Treatment of series may run into similar problems to species delimitation, namely, the existence of atypical forms that obscure taxon limits. Also, some species, for example, Crataegus flabellata (ser. Tenuifoliae), may act as a connecting link to another series, here ser. Rotundifoliae. Both kinds of issue can necessitate repeated keying out of some series. However, rather than amalgamating the series recognized into larger, even more amorphous, ill-defined entities to mitigate these problems, it is preferred to maintain the series in a familiar Palmerian sense preserving the time-tested utility of their core elements.
Species that are similar in flower may often be readily distinguished in fruit and vice versa; users of this text are encouraged to verify identification from the same plant at both seasons.
Variation occurs in the thorns. Compound thorns, which are adventitious and indeterminate, occur on the trunks of many species. Thorns on twigs, which develop with the new growth, persist a few years and are of two kinds. Determinate thorns (aphyllous thorns of K. I. Christensen 1992) are lateral and are the only type found in North American native species. They have diagnostic value, varying in abundance, color in their second year, length, curvature, and stoutness. Indeterminate thorns, as found in Eurasian species of sect. Crataegus, commence as lateral or terminal growths and may develop into thorn-tipped shoot systems.
Leaves supply useful characters for Crataegus taxonomy, but variation within a plant may be confusing. Median leaves of short shoots are the normal standard for descriptions; they are relatively invariant in size and form. Size at anthesis varies according to species from 0% to 100% mature size. Lobing, here often expressed as Leaf Incision Index, or LII, varies from 0% (not incised) to 100% (incised to midvein). As LII typically diminishes towards the leaf apex, maximum LII is usually used. Leaves on extension shoots are often larger, more deeply incised, sometimes of a completely different shape from short-shoot leaves, and may be more variable on one plant. Although apparently diagnostic in some cases, they are insufficiently known and too difficult to describe to be generally useful for description.
Hawthorns may possess both leaflike bracts and bracteoles in the inflorescence, the former being either relatively few or absent. Bracteoles are often relatively numerous and can usually be found throughout young inflorescences; they are sparse in some species. Typical bracteoles of North American hawthorns are caducous, more or less linear-oblong to linear, bilaterally symmetric, and membranous with glandular margins. Some North American hawthorns have larger, harder, more or less herbaceous and more persistent bracteoles. A different bracteole type found in some North American hawthorns (for example, Crataegus brachyacantha) is smaller than any of the above and more or less lacking marginal glands.
Fruit color change during development is a valuable distinguishing character in some cases. In comparing two sympatric species, it is critical to compare them at the same time and a good example is found with Crataegus okennonii versus C. douglasii. Although pomes both finish black, pomes of C. douglasii are usually already black when those of C. okennonii are brownish or reddish, as illustrated in J. B. Phipps et al. (2003).
Crataegus is best treated as sister to Mespilus (E. Y. Y. Lo and M. Donoghue 2012; Li Q. Y. et al. 2012); other relationships in tribe Pyreae are less close. Molecular evidence (C. S. Campbell et al. 2007; D. Potter et al. 2007) shows that the Amelanchier clade is sister to Crataegus-Mespilus, but Amelanchier is different in many morphologic features.
The following names could not be accounted for in the current treatment: Crataegus ardua Sargent, C. brachyphylla Sargent, C. evansiana Sargent, C. faxonii Sargent var. praetermissa (Sargent) E. J. Palmer, C. glareosa Ashe, C. harryi Sargent, C. immanis Ashe, C. lecta Sargent, C. littoralis Sargent, C. menandiana Sargent, C. mercerensis Sargent, C. pilosa Sargent, C. pinguis Sargent, C. populifolia Walter, C. sublobulata Sargent, and C. whitakeri Sargent.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 128 (119 in the flora).
Section Coccineae includes 20 series and constitutes the main North American hawthorn diversification which comprises a single clade when sect. Macracanthae is included (E. Y. Y. Lo et al. 2009). Variation in habit, leaf shape, glandularity, and other characters, permits recognition of more or less distinct series; the delimitation of some series may warrant further attention. Most groups with leaf lobes absent, for example, ser. Aestivales, Crus-galli, Punctatae, and Madrenses, are found here, as are series that tolerate particularly extreme conditions for Crataegus, for example, ser. Aestivales (southeastern wetlands) and ser. Lacrimatae (southeastern xeromorphs).
Series Anomalae and ser. Macracanthae are often included in sect. Coccineae; here they are placed in sect. Macracanthae because their pyrenes are pitted.
Series Microcarpae (sect. Crataegus) is included at couplet 44 below to handle common forms that key out there with little lobing and, thus, no veins to sinuses. The interserial hybrids Crataegus persimilis and C. ×sicca key out at couplets 16 and 20, respectively; C. turnerorum keys out in part at couplets 18 and 31.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Leaves: evidently lobed (except in some small-leaved specimens of C. spathulata, ser. Microcarpae), veins to both lobes and deeper sinuses | → 2 |
1. Leaves: lobed or not, veins absent to sinuses | → 3 |
2. Inflorescences: falcate bracteoles subtending lower branches absent, branches glabrous or pubescent; pomes vermillion to red or orange-red; leaf blades 1.4–6 cm; styles 1–3; pyrene sides usually plane (except grooved in ser. Crataegus). | sect. Crataegus |
2. Inflorescences: falcate bracteoles subtending lower branches present, branches glabrous; pomes yellowish to tan; leaf blades 5–9 cm; styles 4 or 5; pyrene sides strongly pitted. | sect. Sanguineae |
3. Inflorescences: falcate bracteoles subtending lower branches present, branches glabrous; mature pomes yellowish to tan; leaf blades 5–9 cm; pyrene sides strongly pitted. | sect. Sanguineae |
3. Inflorescences: falcate bracteoles subtending lower branches absent, branches glabrous or pubescent to tomentose; mature pomes usually red to black, rarely yellow to orange; leaf blades 2–8(–12) cm; pyrene sides plane or concave, eroded, or pitted | → 4 |
4. Pomes red or bright red at full maturity, or colors other than deep red to black | → 5 |
4. Pomes deep red to purple or black at full maturity, sometimes bright red when immature | → 6 |
5. Mature pomes orange to red; pyrene sides ± pitted or eroded. | sect. Macracanthae |
5. Mature pomes usually red, sometimes orange, yellow, or pink-mauve (sometimes ± pruinose), sometimes remaining green until late, or green-blotched; pyrene sides plane to concave. | sect. Coccineae |
6. Pyrene sides usually pitted, sometimes only shallowly. | sect. Douglasia |
6. Pyrene sides ± plane, sometimes shallowly concave (C. ursopedensis, ser. Rotundifoliae) | → 7 |
7. Leaves glossy; thorns on twigs 1–1.5 cm, recurved; post-mature petals ± orange; anthers cream to orange; Louisiana and adjacent states. | sect. Brevispinae |
7. Leaves matte; thorns on twigs 2.5–4 cm, ± straight; post-mature petals turning pale brown; anthers pale pink to pink, pink-purple, or ivory; n Great Plains, ne United States, and adjacent Canada | → 8 |
8. Leaf blades: lobes absent or very short, length (1.2–)1.6–2(–2.4) times width, veins 6–8 per side; stamens 20, anthers pink-purple or ivory; ne United States and adjacent Canada. | sect. Coccineae |
8. Leaf blades: lobed, length 1.2–1.5 times width, veins (3–)5–8 per side; stamens 10, anthers pale pink to pink; Cypress Hills, w Canada only. | unassigned (ser. Montaninsulae) |
1. Inflorescences 2–6-flowered (± umbellate); flowering before or with young leaves, anthesis very early, before other sympatric hawthorns; pomes ripe May–late June; se United States, wetlands. | C. ser. Aestivales |
1. Inflorescences usually 7–25-flowered (if 1–6-flowered, not ± umbellate); not flowering before or with young leaves, anthesis later; pomes ripe August–October; mostly in toplands, except few se United States species | → 2 |
2. Bracteoles, at least larger, usually ± herbaceous, usually ± persistent, others sometimes membranous but sometimes caducous; flowers 18–30 mm diam | → 3 |
2. Bracteoles usually ± membranous, sometimes ± herbaceous, usually caducous, sometimes fugacious or ± persistent, rarely deciduous; flowers 8–25(–26) mm diam | → 8 |
3. Leaves and petioles eglandular or sparsely glandular | → 4 |
3. Leaves and petioles gland-dotted or stipitate-glandular | → 5 |
4. Pomes orange-red, bright or deep red, or bright yellow, not pruinose; flesh mealy; fruiting sepals erect or erect-patent to broadly spreading, rarely incurved, often ± accrescent; larger bracteoles narrowly oblong, abaxially villous. | C. ser. Molles |
4. Pomes bright pink to crimson, glabrous or pubescent at ends; flesh ± hard; fruiting sepals spreading or ± reflexed, non-accrescent; larger bracteoles oblong to curved, abaxially glabrous. | C. ser. Dilatatae |
5. Flowers 25–30 mm diam.; stamens 10 or 30–45(–47); shrubs multi-stemmed, main trunk not dominant; leaf blades ± chartaceous; inflorescences frequently arising laterally from extension shoots. | C. ser. Triflorae |
5. Flowers 18–25 mm diam.; stamens (5 or)10 or 20–25; shrubs or trees 1- to few-stemmed, main trunk dominant; leaf blades usually thick and ± chartaceous or thinner but subcoriaceous; inflorescences either arising solely subterminally from woody short shoots (ser. Molles, ser. Dilatatae), or sometimes arising laterally from extension shoots (ser. Bracteatae) | → 6 |
6. Leaves: lobes 0 or 1–4 per side, merely apiculi or sinuses very shallow, deep green, subcoriaceous; petioles 15–25% length of blade; inflorescences 3–12-flowered; stamens 20(–25); larger bracteoles ligulate, semipersistent, margins strongly stipitate-glandular. | C. ser. Bracteatae |
6. Leaves: lobes usually 1–6 per side, distinct, sinuses shallow to deep, green or bluish green, ± thick or chartaceous; petioles 30–50% length of blade; inflorescences 5–20-flowered; stamens (5 or)10 or 20; larger bracteoles narrow to linear, subherbaceous, margins sessile-glandular (ser. Molles), or larger bracteoles oblong to curved, abaxially glabrous, margins strongly stipitate-glandular (ser. Dilatatae) | → 7 |
7. Pomes orange-red, bright or deep red, not pruinose; flesh mealy; fruiting sepals erect or erect-patent to broadly spreading, rarely incurved, often ± accrescent; larger bracteoles narrowly oblong, abaxially villous. | C. ser. Molles |
7. Pomes bright pink to crimson, glabrous or pubescent at ends; flesh ± hard; fruiting sepals spreading or ± reflexed, not accrescent; larger bracteoles oblong to curved, abaxially glabrous. | C. ser. Dilatatae |
8. Petioles usually eglandular; if petioles ± glandular, sepal margins not glandular-denticulate, -serrate, or -laciniate | → 9 |
8. Petioles, at least some, glandular; sepal margins glandular-denticulate, -serrate, -laciniate, or -pectinate | → 33 |
9. Leaves: lobes 0 or not much bigger than teeth | → 10 |
9. Leaves: lobes evident and distinct | → 21 |
10. Bracteoles linear-filiform, margins eglandular or sparsely glandular; pomes 5–8 mm diam | C. ser. Virides |
10. Bracteoles narrowly elliptic, linear, or narrow, margins sparsely glandular; pomes 8–15 mm diam | → 11 |
11. Sepal margins entire or slightly glandular-serrate | → 12 |
11. Sepal margins glandular-serrate to glandular-laciniate or -pectinate | → 16 |
12. Leaf blades usually ± thin or chartaceous, matte | → 13 |
12. Leaf blades subcoriaceous, glossy | → 14 |
13. Inflorescence branches pubescent. | C. ser. Punctatae |
13. Inflorescence branches glabrous. | C. ser. Rotundifoliae |
14. Leaves and inflorescence branches glabrous. | C. ser. Crus-galli |
14. Leaves and inflorescence branches hairy, particularly young | → 15 |
15. Styles and pyrenes 1–3; se United States. | C. ser. Crus-galli |
15. Styles and pyrenes 3–5; Texas. | C. ser. Madrenses |
16. Pyrene sides pitted. | C. persimilis |
16. Pyrene sides plane | → 17 |
17. Leaf blades ± isodiametric, blue-green mature, woolly. | C. ser. Molles |
17. Leaf blades longer than wide, green to dark green mature, appressed- or scabrous-pubescent, glabrous, or white-tomentose | → 18 |
18. Leaves: veins 3 per side; stamens 15. | C. turnerorum |
18. Leaves: veins 4–7 per side; stamens 10 or 20 | → 19 |
19. Petiole length 20–30% blade; blades matte, villous to tomentose. | C. ser. Greggianae |
19. Petiole length usually 20–50% blade; blades glossy, glabrous or sparsely appressed-pubescent | → 20 |
20. Leaf blades scabrous, veins 5 or 6 per side; Texas. | C. ser. Madrenses |
20. Leaf blades glabrous, veins 7 per side; n United States, adjacent Canada. | C. ×sicca |
21. Inflorescence branches pubescent | → 22 |
21. Inflorescence branches glabrous | → 27 |
22. Bracteoles linear-filiform, margins eglandular or sparsely glandular. | C. ser. Virides |
22. Bracteoles linear to oblong, margins stipitate- or sessile-glandular | → 23 |
23. Sepal margins glandular-laciniate to -serrate; leaf blades hard, chartaceous, or coriaceous; fruiting sepals erect or erect-patent, sometimes spreading | → 24 |
23. Sepal margins entire or subentire; leaf blades thin; fruiting sepals erect-patent to recurved | → 25 |
24. Leaf blades broadly ovate or broadly elliptic to rhombic-elliptic, 2.5–4(–5) cm; flowers 15 mm diam.; c Texas, ± xeromorphs. | C. ser. Greggianae |
24. Leaf blades broadly elliptic to ovate, 4–8(–12) cm; flowers 18–22 mm diam.; e Texas to Alabama n to Minnesota and Quebec, mainly mesophytes. | C. ser. Molles |
25. Flowers (10–)13–17(–26) mm diam | C. ser. Tenuifoliae |
25. Flowers 18–23 mm diam | → 26 |
26. Fruiting sepals sessile. | C. ser. Punctatae |
26. Fruiting sepals elevated. | C. ser. Pruinosae |
27. Inflorescences (10–)15–30+-flowered, bracteoles linear-filiform (length/width = 10–20:1), margins eglandular or sparsely glandular; pomes 5–8 mm diam.; leaves with tufts of hair in abaxial vein axils (not discernable in rare pubescent form); southeastern, damp ground. | C. ser. Virides |
27. Inflorescences 3–15-flowered, bracteoles linear or narrowly elliptic, margins sessile- or stipitate-glandular; pomes 7–15(–20) mm diam.; leaves lacking tufts of hair in abaxial vein axils; topland species | → 28 |
28. Leaves: adaxial surfaces of young blades glabrous (except along veins in some taxa and on whole adaxial surface in C. virella); pomes pink, mauve, or pale green, sometimes scarlet, deep crimson, or purple, often strongly pruinose, flesh hard; fruiting sepals usually on prominent collar. | C. ser. Pruinosae |
28. Leaves: adaxial surfaces of young blades glabrous or sparsely hairy; pomes yellow to reddish mature, not strongly pruinose, flesh hard or mellow; fruiting sepals usually sessile, sometimes slightly elevated | → 29 |
29. Twigs 1–2-years old dark brown, dark purple-brown, or reddish brown to blackish, often ± pruinose | → 30 |
29. Twigs 1–2-years old not both purple-brown and ± pruinose | → 31 |
30. Leaves: veins 4–6 per side, blades 2.5–4(–5) cm; petioles eglandular, length 25–33% blade; stamens 10. | C. ser. Greggianae |
30. Leaves: veins 3–5(or 6) per side, blades 2–7 cm; petioles sparsely glandular, length 20–30% blade; stamens 10(or 20). | C. ser. Populneae |
31. Stamens 15, anthers purple; c Texas. | C. turnerorum |
31. Stamens 5–10 or 20, anthers pink to purple or ivory; e, n United States, adjacent Canada | → 32 |
32. Leaves: lobes well defined, lobe apices usually acute, blades 3–6(–8) cm, apices acute; petioles glandular or eglandular; anthers pink to red or purple; pomes red, ellipsoid to suborbicular, sepals erect-patent to recurved or erose. | C. ser. Tenuifoliae |
32. Leaves: lobe sinuses usually shallow, lobe apices subacute to obtuse, sometimes acuminate, blades 2–4(–5) cm, apices acuminate to obtuse; petioles eglandular or with 1–2 tiny glands; anthers ivory, sometimes pink; pomes usually bright to deep red or yellowish, sometimes orangish or burgundy, usually ± suborbicular, sometimes ellipsoid or oblong, sepals reflexed. | C. ser. Rotundifoliae |
33. Petioles, at least some, stipitate-glandular; bracteole margins usually short-stipitate- to stipitate-glandular | → 34 |
33. Petioles sessile-glandular; bracteole margins usually sessile-glandular to short-stipitate-glandular, except stipitate-glandular in ser. Intricatae, ser. Pulcherrimae, or C. dodgei group (larger bracteoles only, or some ser. Lacrimatae), rarely ± eglandular | → 40 |
34. Leaf blades ± elliptic to narrowly obovate or ovate, lobes 0 or obscure, subcoriaceous, (shiny at maturity); pomes orange-red to red, sepals not elevated on collar. | C. ser. Bracteatae |
34. Leaf blades broadly elliptic to elliptic, ovate or deltate, broadly ovate to rhombic-elliptic or rhombic, lobes 0 or 1–5 (if lobes 0, not elliptic to narrowly obovate), if so, short to moderately deep, usually ± thin, (not particularly shiny at maturity); pomes yellow to red, sepals ± elevated on collar, sometimes sessile | → 35 |
35. Pomes with sepals sessile; se United States | → 36 |
35. Pomes with sepals ± elevated on collar; e or se United States | → 37 |
36. Leaf blades 3–5 cm, elliptic to broadly elliptic or suborbicular, base rounded to broadly truncate, lobes 3 or 4 per side, distinct, veins 4 or 5 per side; inflorescence branches coarsely hairy. | C. ser. Populneae |
36. Leaf blades 2.5–4(–5) cm, ovate to obovate or rhombic-ovate, base ± cuneate, lobes 0 or 1–3 per side, obscure, veins 5 or 6(or 7) per side; inflorescence branches appressed-scabrous. | C. ser. Apricae |
37. Stamens 10; trunk bark fibrous, checked into longitudinal plates or corrugated; e United States to Missouri. | C. ser. Intricatae |
37. Stamens 20; trunk bark often corrugated; Texas to Georgia. | C. ser. Pulcherrimae |
38. Inflorescence branches hairy. | C. ser. Intricatae |
38. Inflorescence branches glabrous | → 39 |
39. Leaf blades 4–7 cm. | C. ser. Pulcherrimae |
39. Leaf blades 2–4 cm. | C. ser. Intricatae |
40. Twigs ± strongly flexuous, rarely slightly flexuous; leaf blades 1–4(–5) cm; (ultimate branches ± conspicuously pendulous, except in dwarf forms less than 10 dm) | → 41 |
40. Twigs straight, only rarely flexuous; leaf blades 2–6(–10) cm; (ultimate branches not especially drooping) | → 44 |
41. Dwarf species usually 0.5–2 m; twigs ± strongly flexuous, ultimate branches not markedly pendulous. | C. ser. Lacrimatae |
41. Larger species usually 2–7 m; twigs slightly to strongly flexuous, upper branches often ± pendulous | → 42 |
42. Leaf blades predominantly narrow, usually elliptic to oblong or narrowly obovate, sometimes obtrullate, ovate, or suborbicualte, usually widest toward tip, veins 1–5 per side (exiting mainly or wholly in apical part of blade), apices obtuse to acute; (upper branches conspicuously drooping). | C. ser. Lacrimatae |
42. Leaf blades suborbiculate to broadly ovate or rhombic-elliptic, veins 1–3 per side in small-leaved forms (1–2 cm), usually 3–5 per side in larger-leaved forms, terminating along leaf length, apices acute to obtuse; (upper branches gently to conspicuously drooping) | → 43 |
43. Leaves, especially young, glabrous or scabrous adaxially; (upper branches often slightly drooping, at most slightly flexuous); bracteoles ± stipitate-glandular; stamens 10 or 20, anthers ivory, cream, or pink to purple or red. | C. ser. Apricae |
43. Leaves, especially young, ± glabrous or woolly-tomentose adaxially; (upper branches drooping, clearly flexuous); bracteoles sessile- to short-stipitate-glandular; stamens 20, anthers ivory or cream. | C. ser. Lacrimatae |
44. Trunk bark smooth and exfoliating; pomes 4–6 mm diam | Crataegus (sect. Crataegus) ser. Microcarpae |
44. Trunk bark rough, scaly, fibrous, checked into longitudinal plates, or corrugated; pomes 8–14(–20) mm diam | → 45 |
45. Leaves: lobes 0 or shallow, sinuate; inflorescences 1–5-flowered; sepals ± equal to petals. | C. ser. Parvifoliae |
45. Leaves: lobes 0 or distinctly lobed; inflorescences 3–15-flowered; sepals shorter than petals | → 46 |
46. Stamens (10–)20; pomes pink, mauve, or pale green, sometimes scarlet, deep crimson, or purple, strongly pruinose, flesh ± hard. | C. ser. Pruinosae |
46. Stamens 10 or 20; pomes reddish or yellowish, seldom strongly pruinose, flesh ± hard to mealy | → 47 |
47. Stamens 13–18, anthers purple. | C. ser. Intricatae |
47. Stamens 5–10 or ca. 20, anthers white to cream or pale pink to pink-purple or red | → 48 |
48. Fruiting sepals elevated on short but distinct collar; glands of at least larger bracteoles clearly stipitate | → 49 |
48. Fruiting sepals sessile; glands of bracteoles sessile or stipitate | → 52 |
49. Stamens 10. | C. ser. Intricatae |
49. Stamens 20 | → 50 |
50. Inflorescence branches hairy; leaves 4–9 cm (rarely glabrous to sparsely hairy; if so, leaves 3–4 cm and anthers rose). | C. ser. Intricatae |
50. Inflorescence branches glabrous; leaves 4–9 cm (if 3–4 cm, anthers white to cream) | → 51 |
51. Fruiting sepals elevated on distinct collar; glands on all bracteoles stipitate; se United States. | C. ser. Pulcherrimae |
51. Fruiting sepals elevated on short collar; glands only on larger, lower bracteoles stipitate; midwestern United States and adjacent Canada. | C. ser. Rotundifoliae |
52. Anthers white to cream, rarely palest pink; bracteoles sessile- or stipitate-glandular | → 53 |
52. Anthers pale pink or pink to red or purple; bracteoles sessile- or very short-stipitate-glandular | → 56 |
53. Bracteoles sessile- or very short-stipitate-glandular; stamens 10 or 20; inflorescence branches glabrous or hairy | → 54 |
53. At least larger bracteoles stipitate-glandular; stamens 10; inflorescence branches glabrous | → 55 |
54. Young leaves: adaxial surfaces glabrous; stamens 10; Delaware. | C. ser. Populneae |
54. Young leaves: adaxial surfaces ± scabrous-hairy; stamens 10 or 20; n United States, s Canada. | C. ser. Rotundifoliae |
55. Shrubs or trees, 4–6 m; all bracteoles stipitate-glandular; Ozarks, possible for se United States. | C. ser. Intricatae |
55. Shrubs, 2–4 m; larger bracteoles stipitate-glandular; ne United States, adjacent Canada. | C. ser. Rotundifoliae |
56. Sepals glandular-denticulate; stamens 10; narrower pyrenes often concave-sided; pomes bright red in late August, becoming deep red at maturity; s Alberta, Saskatchewan. | Crataegus (sect. unassigned) ser. Montaninsulae |
56. Sepals usually glandular-serrate; stamens 10 or 20; all pyrenes plane-sided; pomes orange to vermillion or bright red, green, or dull red, becoming bright or deep red or burgundy at maturity; n, ne United States, s Canada | → 57 |
57. Anthers very pale pink or pale cream-pink; inflorescence branches glabrous | → 58 |
57. Anthers pink to pink-purple or red; inflorescence branches glabrous or hairy | → 59 |
58. Anthers pale cream-pink; stamens 10; mature fruit orange to orange-brown or orange-red; Ozarks, possible for se United States. | C. ser. Intricatae |
58. Anthers very pale pink; stamens 20; mature fruit burgundy; British Columbia. | C. ser. Rotundifoliae |
59. Inflorescence branches glabrous. | C. ser. Populneae |
59. Inflorescence branches hairy | → 60 |
60. Shrubs 4–10 m; leaves 5–9 cm; lobes usually shallow, but if deeper, broad; flowers 16–22 mm diam.; fruits 10–14 mm; Great Lakes to New England s in Appalachians to North Carolina. | C. ser. Coccineae |
60. Shrubs 3–5 m; leaves 3–7 cm; lobes moderately deep, acute; flowers 13–17 mm diam.; fruits 8–10 mm; se Canada, ne United States | → 61 |
61. Leaf blades usually thin, often glossy, apices acute, lobe apices acuminate; inflorescence branches villous; sepal margins usually glandular-serrate, rarely nearly entire and eglandular; styles 3–5; pomes ellipsoid. | C. ser. Tenuifoliae |
61. Leaf blades thin to chartaceous, matte, apices and lobe apices acute to subacute; inflorescence branches densely pubescent or villous; sepal margins glandular-serrate; styles 3 or 4(or 5); pomes suborbicular. | C. ser. Rotundifoliae |
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