1922) SARGENT, NOTES ON NORTH AMERICAN TREES, X 197 



in its flowers 2 cm . in diameter, in its slightly villose corymbs, and in its 

 larger fruit up to 1.5 cm. in diameter, with a more prominent calyx with 

 often erect lobes. 



The description of C. aboriginum was based on a single individual 

 found by Mr. J. G. Jack at Caughnawaga in the Province of Quebec 

 in 1899 and 1890; it has since been collected at other stations, and a further 

 acquaintance with this plant shows by intermediate forms that it cannot 

 be distinguished specifically from C. rotundifolia . The larger leaves, 

 flowers and fruit, and the slightly villose pedicels of the most of plants 

 examined make it, however, desirable to distinguish it as a variety. 



The original plant of C. aboriginum was a shrub with stems only 3 m. 

 high; the plants of St. Annes de Bellevue are trees from 7-8 m. tall. The 

 following additional specimens are referred to this variety. 



Canada. Province of Q u e b e c, Caughnawaga, /. G. Jack, No, 97, Sep- 

 tember 24, 1000, St. Annes de Bellevue, near Macdonald College, /. G. Jack, 

 Nos. 207 and 208, September 23, 1913, May 30, 1914; La Tortue, Brother M. 

 Victorin, October 1920; Hill County, ./. Dunbar, Nos. 172 and 187, September 

 18, 1915. Province of Ontario, Gananoque, /. Dunbar, No. 18, June 11 and 

 September 27, 1907, No. 66, September 1911, Belleville, J. Dunbar, No. 62, 

 June 3, 1908, and September 26, 1907, Kingston, J, Dunbar, No. 128, October 

 14, 1912, June 1, 1913. 



Crataegus rotundifolia f. rubescens, n. forma. 



Differing from the type only in the distinctly red color of the leaves 

 in spring and summer. 



Canada. Province of Quebec, St. Anne, Montreal Island, J. G. Jack, 

 No. 202 (type), May 29 and September 23, 1913, Baie d'Urfe Station, G. T.R.R.. 

 J. G. Jack, No. 206, September 23, 1913, No. 215, May 30 and September 25, 1914, 



Plants raised at the Arboretum from the seed of No. 215 have retained 

 the red color of their leaves. 



Crataegus mercerensis (§ Rotundifoliae), n. sp. 



Leaves obovate to rarely ovate or semiorbicular, acute and short- 

 pointed at apex, concave-cuneate at the entire base, usually slightly 

 divided above the middle into short acute lobes, finely often doubly 

 serrate with straight gland-tipped teeth, thin, glabrous, smooth and dark 

 yellow-green on the upper surface, pale on the lower surface, 4-6 cm. long 

 d 3-4 cm. wide, with a thin midrib and slender veins running to the 

 points of the lobes; petioles slender, narrowly wing-margined at apex, 

 often furnished with occasional glands, sparingly villose on the upper 

 side early in the season, soon glabrous, 1-2 cm. in length. Flowers appear- 

 ing from the middle to the end of May, about 1 cm. in diameter, on slender 

 glabrous pedicels in 5-12-flowered glabrous compact corymbs with lanceo- 

 late to linear glandular caducous bracts and bractlets; calyx-tube narrow- 

 obconic, glabrous, the lobes abruptly narrowed from a wide base, short, 

 serrate toward the acute or rarely 3-lobed apex, glabrous on the outer 

 surface, slightly villose on the inner surface; stamens 10; anthers white; 

 styles usually 3. Fruit ripening the end of September, on erect pedicels 



