ROSACEA 



445 



calyx only slightly enlarged, with closely appressed coarsely serrate lobes often 

 deciduous from the ripe fruit; flesh yellow, thin, acidulous, juicy; nutlets 4 or 5, 

 thin, gradually narrowed and acute at the ends, irregularly ridged and sometimes 

 grooved on the back, about |' long. 



A tree, 25-30 high, with a trunk sometimes a foot in diameter and 6 or 7 long, 

 covered with close light gray bark tinged with red and divided by shallow fissures 

 into small plates, stout ascending branches forming an open irregular often round- 

 topped head, and slender nearly straight branchlets densely villose when they first 

 appear, dark orange color tinged with red and sparingly villose when the flowers 

 open, becoming bright red-brown and lustrous at the end of their first season and 

 dark dull reddish brown the following year, and sparingly armed with slender nearly 

 straight red-brown shining spines l^'-2' long. 



Distribution. Open woods near the borders of streams in moist rich soil; north- 

 eastern Illinois, Thatcher's Park, Glendon Park, and River Forest, near Chicago; 

 not common. - 



** Stamens 10-20, usually 10. 



77. Crataegus assurgens, Sarg. 



Leaves broadly ovate, acuminate, rounded or rarely cuneate at the wide entire 

 base, sharply doubly serrate above, with straight gland-tipped teeth, and slightly 



""^-V^^;^ 



divided into 3 or 4 pairs of small acuminate lobes, about one third grown when the 

 flowers open the middle of May and then roughened above by short white hairs and 

 glabrous or sparingly villose below, with persistent hairs along the slender yellow 

 midribs, and the veins arching obliquely to the points of the lobes, and at maturity 

 membranaceous, dull dark green and scabrate on the upper surface, light yellow- 

 green on the lower surface, 2|'-3y long, 2^-2^' wide ; their petioles slender, villose 

 early in the season, becoming pubescent, I'-l^' long; on vigorous shoots often deeply 

 lobed, very coarsely serrate, sometimes 4' long and wide, with long stout glandular 

 petioles, and foliaceous lunate acuminate coarsely glandular-serrate persistent stip- 

 ules. Flo"wers f '-|' in diameter, on short villose pedicels, in compact 8-lo-flowered 

 hairy corymbs, with oblong, acuminate, glandular bracts and bractlets, deciduous 



