POMACEAE (APPLE FAMILY) 267 



2. CRATAEGUS L.* HAWTHORN 



Shrubs or small trees with thorny branches, simple alternate toothed or 

 lobed leaves, and usually white flowers in corymbs. Calyx-tube urn-shaped; 

 its limb 5-parted. Petals 5, spreading. Stamens 5-20. Ovary 2-5-celled, 

 becoming a drupe containing 2-5 bony 1-seeded carpels. 



Spines short, 2 cm. long or less (in no. 2 sometimes more). 



Leaves elliptic to lanceolate, serrate, quite small (1.5 cm. or less 



broad) . . . . . . . . . . .1.0. saligna. 



Leaves ovate or obovate, 2-4 cm. broad. 



Serrate, not incisely toothed or lobed; petiole without glands . 2. C. rivularis. 



Lobed or incisely and doubly toothed; petiole with scattered 



glands 3. C. Douglasii. 



Spines long, 3-8 cm. 



Teeth of leaves gland-tipped. 



Leaves small, 1.5 cm. or less broad . . . . . . 1. C. saligna. 



Leaves large, mostly 3-5 cm. broad. 



Leaves thin, shiny above but with scattered hairs: pedicels 



glabrous; anthers rose-color; fruit mahogany-brown . . 4. C. cerronis. 

 Leaves thick. 



Petioles glandular; fruit pyriform, dark red; nutlets 2-3 . 5. C. Doddsii. 

 Petioles nearly or quite glandless; fruit subspherical, scarh . 



nutlets 3-5 0. C. sheridana. 



Teeth of leaves not gland-tipped; fruit blood-red. 



Twigs of season glabrous; anthers pink; fruit spherical . . .7. C. coloradensis. 

 Twigs of season woolly, villous, or pubescent; anthers white. 



Petioles one fourth to one fifth the length of the leaf-blades; 



fruit broader than long . . . . . . 8. C. occidentalis. 



Petioles one third to one half the length of the leaf-blade; fruit 



spherical or elongated 9. C. coloradoides. 



1. Crataegus saligna Greene, Pitt. 3: 99. 1896. A slender tree 2-6 m. 

 high, with slender willowy branchlets: leaves oblong or oblong-lanceolate, 

 3-5 cm. long, firm, acute or obtuse at apex, cuneately narrowed to the slender 

 petiole, minutely eremite-serrate above the middle, glabrous below, obscurely 

 appressed-strigulose on the glossy upper surface: spines slender, flexible, 



black, 2-3 cm. long: corymb glabrous, few-flowered: calyx-lobes tri- 

 angular: petals suborbicular, about 4 mm. in diameter: stamens 20: styles 5: 

 fruit subglobose, black with bloom, dry, mealy, insipid. (C. Wheeleri A. Nels. 

 Bot. Gaz. :M: :!(i ( .). 1902.) Canons of west-central Colorado. 



2. Crataegus rivularis Nutt. T. & G. Fl. N. A. 1: 464. 1840. A small tree, 

 well branched; the branchlets rather slender: leaves 3-6 cm. long, bright 

 green and glossy, glabrous except for some obscure hairs above, ovate or 

 elliptic-ovate, usually acute, serrate, the teeth short: spines moderately stout, 

 glossy, somewhat curved, 2-4 cm. long: corymb glabrous, several-flowered: 

 calyx-lobes with a linear non-glandular acumination : petals orbicular, crenate 

 at summit: stamens 10: styles 5: fruit nearly black, 1 cm. in diameter. 

 Stream banks; western Wyoming to Utah and Idaho; probably in northwest- 

 ern Colorado. 



3. Crataegus Douglasii Lindl. Bot. Reg. pi. 1810. 1835. A stout shrub or 

 small tree, 4-8 m. high, well branched; spines stout, rarely more than 2 cm. 

 long: leaves elliptic to obovate, usually cuneate at base, irregularly serrate, 

 those of the young shoots often incisely lobed, 3-6 cm. long, glabrous or some- 

 times slightly pubescent on both sides: corymb 10-15-flowered, nearly gla- 

 brous or slightly tomentulose, not glandular: calyx-lobes entire, triangular- 

 subulate: petals orbicular, 6-8 mm. in diameter: .stamens 10: fruit black, 

 or purplish-black; the carpels 3-4. Northern Wyoming (apparently), west- 

 ward through Montana and Idaho to Oregon. 



4. Crataegus cerronis A. Nels. Bot. Gaz. 34: 370. 1902. Small tree, 

 widely branched, 2-5 m. high; trunk short, stout, with rough bark; young 

 twigs brown; lenticels small, nearly white: leaves broadly elliptic-ovate, 

 3-5 cm. long, coarsely serrate; the teeth with finer gland-tipped serrations, 



* Nomenclature and synonomy supplied by Prof. Francis Ramaley of the University 

 of Colorado, who has studied critically the Rocky Mountain species of the genus both in 

 field and herbarium. He suggests that with further study it may be found desirable to 

 unite C. Doddsii with C. sheridana. 



