New York Metropolitan Flora

Genus: Crataegus

Crataegus crus-galli
Crataegus crus-galli

By Science Staff

Not peer reviewed

Last Modified 01/18/2012

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Nomenclature

Crataegus L., Sp. Pl. 475. 1753. Gen. Pl., ed. 5, 213. 1754. Oxyacantha Medik., Philos. Bot. 1: 150, 154, 155. 1789, nom. illeg. (Art. 52.1). LECTOTYPE: Crataegus oxyacantha L., designated by Britton & Brown (1913).

Xeromalon Raf., New Fl. 3: 11. 1838. TYPE: Xeromalon obovatum Raf.

Phaenopyrum M. Roem., Fam. Nat. Syn. Monogr. 3: 152. 1847. TYPE: Unknown.

Phalacros Wenz., Linnaea 38: 164. 1874. TYPE: Phalacros cordatus (Mill.) Wenz. (=Crataegus phaenopyrum (L. f.) Medik.).

Key to the species of Crataegus

1. Flowers solitary or rarely 2-3 together; shrub to 2 m...Crataegus uniflora
1. Flowers in compound (rarely simple) cymes; plants often arborescent...2

2. Leaves with some of the primary lateral veins running to (or toward, forking just before) the sinuses as well as to the points of the lobes; flowers 0.7-1.3 cm wide...3
2. Leaves with the primary lateral veins running only to (or toward) the points of the lobes (if any); flowers often larger...4

3. Fruit 4-6 mm thick; thorns 2.5-6 cm long; styles and nutlets 1 (2 or 3)...Crataegus monogyna
3. Fruit 6-9 mm thick; thorns mostly 0.5-1.5 cm long; styles and nutlets 3-5...Crataegus phaenopyrum

4. Bracts of the corymb numerous, conspicuously and copiously stipitate-glandular on the margins; petioles glandular; corymbs and leaves essentially glabrous (or a few hairs on the veins above); corymbs few- (rarely more than 8-) flowered, somewhat simple or umbelliform...Crataegus intricata
4. Bracts of corymb usually few and/or the glands sparse or absent; petioles eglandular or the corymbs villous; leaves various; corymbs usually many-flowered...5

5. Nutlets with deep or shallow pits or depressions on their ventral surfaces; plants flowering in June or latter half of May...6
5. Nutlets plane, not pitted ventrally; plants flowering in April, May, or early June...7

6. Mature leaf blades somewhat coriaceous, thickened at margins, the veins usually rather deeply impressed above, glabrous to pubescent on both surfaces; corymbs, new branches, and petioles glabrous to sparcely villous; thorns 2.5-9.5 cm long, usually numerous...Crataegus succulenta
6. Mature leaf blades thin, the veins (except sometimes along the midrib) scarcely if at all impressed above, strigose above and usually pubescent beneath; branchlets of current year, and petioles all usually villous or lightly tomentose; thorns ca. 2.5-5 cm long...Crataegus calpodendron

7. Blades of at least the floreal leaves somewhat acute to broadly or (more commonly) narrowly tapered or cuneate at their bases...8
7. Blades of both floreal and vegetative leaves mostly broadly rounded, truncate, or subcordate at their bases...10

8. Blades (at least of floreal leaves) mostly elliptic to ovate, broadest at or below the middle, often somewhat definitely lobed, usually 1-1.5 times as long as broad, often thin...Crataegus chrysocarpa
8. Blades (especially the floreal leaves) mostly obovate to oblong-elliptic, broadest above or rarely at the middle, unlobed or very obscurely lobed near the apex, mostly 1.5-3 or more times as long as broad, usually thickish or coriaceous (except sometimes in the shade)...9

9. Leaves glossy above, the veins not (or only slightly) impressed; petioles mostly less than 1 cm long; styles and nutlets 1-3; stamens ca. 10 or 20...Crataegus crusgalli
9. Leaves dull above, the veins rather conspicuously impressed; petioles mostly 1-2 cm long; styles and nutlets 3-5; stamens ca. 20...Crataegus punctata

10. Corymbs, calyces, and leaves (at least along main veins) beneath somewhat densely villous-tomentose; fruits short-villous at least at the ends...11
10. Corymbs, calyces, and leaves glabrous or pubescent; fruits glabrous...12

11. Stamens ca. 10; fruit pyriform or obovoid...Crataegus submollis
11. Stamens ca. 20; fruit subglobose (ocassionally oblong-ovoid)...Crataegus mollis

12. Young leaves roughened above with short appressed hairs; stamens usually 10 or fewer; fruit with a small sessile calyx...13
12. Young leaves glabrous or pubescent; stamens 10 or 20; fruit with a large prominent calyx...14

13. Flowering corymbs more or less villous...Crataegus flabellata
13. Flowering corymbs glabrous...Crataegus macrosperma

14. Floreal leaves usually ovate or deltate; stamens 10-20; young leaves glabrous to pubescent above...Crataegus pruinosa
14. Floreal leaves usually oblong-ovate; stamens 10 or fewer; young leaves strigose above...Crataegus pedicellata

List of Crataegus Species

Crataegus biltmoreana Crataegus brainerdii Crataegus calpodendron Crataegus chrysocarpa Crataegus crus-galli Crataegus flabellata Crataegus intricata Crataegus iracunda Crataegus jesupii Crataegus macrosperma Crataegus mollis Crataegus monogyna Crataegus pedicellata Crataegus phaenopyrum Crataegus pringlei Crataegus pruinosa Crataegus punctata Crataegus submollis Crataegus succulenta Crataegus uniflora

References to Crataegus

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