Nuttall's Thorn 



481 



The leaves are ovate or obovate to broadly ovate, 2 to 7 cm. long, i to 6 cm. 

 wide, pointed or short-pointed at apex, 

 wedge-shaped at base, doubly toothed and 

 lobed, covered with pale hairs, particularly 

 along the veins above, dark green above, 

 half-leathery, seldom becoming smooth 

 along the veins; leaf-stalks slightly winged, 

 hairy, glandular, i to 3 cm. long. The 

 flowers are about 15 mm. wide, in many- 

 flowered smooth or short-hairy corymbs; 

 calyx-lobes short-pointed to long-pointed, 

 generally long-hairy above and often tinged 

 with red; stamens 10 to 20; anthers Ught 

 yellow; styles 3 to 5. The fruit, which 

 ripens early, is short-oblong and black, its 

 flesh yellow and sweet; it contains 3 to 5 nutlets, commonly 4, 5 to 6 mm. long, 

 the nest of nutlets 5 to 7 mm. thick; the nutlets are ear-shaped, pointed below, 

 ridged on the back, the inner surface bearing rough shallow pits. 



Fig. 439. — Douglas' Thom. 



SO. NUTTALL'S THORN — Crataegus rivularis Nuttall 



CratcBgus Wheeleri Rydberg 



Nuttall's thom occurs about the banks of mountain streams from southeastern 

 Idaho and southwestern Wyoming, southward through the Wahsatch Mountains 



to southwestern Colorado and westward 

 to the Clover Moimtains, Nevada. It is 

 a tree sometimes 6 meters high, with 

 strongly ascending branches, forming a 

 long crown; the bark is dark brown, 

 scaly; the twigs are bright red-brown, 

 occasionally armed with slender spines 

 1.5 to 4 cm. long. 



The leaves are lanceolate to narrowly 

 elliptic, 2.5 to 8 cm. long, 1.5 to 4.5 cm. 

 wide, long-pointed or pointed at the 

 apex, strongly wedge-shaped at the base, 

 toothed or shghtly doubly toothed, the 

 teeth gland-tipped, hairy, particularly 

 along the veins on the upper surface, 

 smooth beneath, thin, dull bluish green above, paler beneath; leaf-stalks winged 

 towards the apex, slightly hairy, i to 2 cm. long. The flowers are at)6ut 12 mm. 

 broad, in many-flowered, smooth corymbs; calyx-lobes lanceolate, long-pointed, 

 sHghtly hairy on the upper surface, remotely glandular-toothed, tipped with red; 



Fig. 440. — Nuttall's Thom. 



