450 



The Thorn Trees 



3. PALMER'S THORN Crataegus Palmeri Sargent 



Palmer's thorn occurs in southwestern Missouri. 



It is a tree sometimes 7 meters high with stout, spreading branches, forming 



a broad round-topped crown; the 

 twigs are smooth and are armed 

 with straight brown spines from 2 

 to 7 cm. long. The leaves are 

 ovate-orbicular, from 2 to 6 cm. 

 long and from 2 to 5 cm. wide, 

 pointed at the apex, wedge-shaped 

 at the base, coarsely toothed, 

 leathery, dark green and shining 

 above, Hght green beneath, smooth; 

 leaf-stalks about i cm. long, shghtly 

 wing-margined. The flowers are 

 about I cm. broad in many- 

 flowered, smooth corymbs; calyx- 

 lobes triangular, long-pointed, re- 

 FIG.3Q2.- Palmer's Thorn. ^^^^^^ toothed, smooth; stamens 



about 10; anthers pale yellow; styles 2 or 3. The fruit, ripening late, is sub- 

 globose, dull green tinged with red, about i cm. thick; flesh yellow, dry, and 

 mealy; it contains 2 or 3 nutlets about 5 mm. long, the nest about 5 mm. thick; 

 nutlets strongly ridged on the back. 



4. CANBY'S THORN - Crataegus Canbyi Sargent 



Canby's thorn occurs from east- 

 em Pennsylvania to the shores of 

 Chesapeake Bay, Maryland. It is a 

 bushy tree, sometimes 6 meters high, 

 with long, ascending branches, form- 

 ing a broad, irregular head; the 

 young twigs are brown, becoming 

 light gray, and are armed with chest- 

 nut-brown spines from 2 to 4 cm. 

 long. 



The leaves are oblong-obovate, 

 from 2.5 to 8 cm. long and from 2 to 

 6 cm. wide, pointed at apex, wedge- 

 shaped at base, doubly toothed, 

 sometimes lobcd, leathery, smooth. 



Fig. 393. Canby's Thorn. 



dark green and shining above, paler and with conspicuous veins beneath; leaf-stalks 



