482 The Thorn Trees 



stamens about 20; anthers yellow; styles 3 to 5. The fruit ripens in September; 

 it is short-oblong, about 8 mm. thick, dark crimson, becoming black; calyx-lobes 

 reflexed; flesh yellow, succulent, mealy; it contains 3 to 5 nutlets 5 to 6 mm. long, 

 the nest 5 to 7 mm. thick; nutlets ear-shaped, ridged on the back, the inner sur- 

 face roughened with shallow pits. 



51. GREENE'S THORN — Oratsegnssaligna Greene 



Greene's thorn grows on the banks of streams of the continental divide in 

 central and southern Colorado, at altitudes from 2000 to 2500 meters. It is a tree 

 sometimes 6 meters high, with long, spreading, or drooping branches; the bark is 

 reddish-brown, scaly on old trees; the twigs are bright red, smooth, and armed with 

 straight, slender, bright red spines from 5 to 25 mm. long. 



The leaves are thick, rhombic-lanceolate, 1.5 to 5 cm. long, 0.5 to 2 cm. broad, 

 roimded, short, or taper-pointed at the apex on the terminal shoots, wedge-shaped 

 at the base, glandular-toothed with short, flattened teeth, those of the terminal 

 shoots toothed or doubly toothed, slightly hairy on the upper surface, particularly 



Fig. 441. — Greene's Thorn. 



along the veins, smooth beneath, dark green and shining above, paler beneath; 

 leaf -stalks winged towards the top, slightly hairy, about i cm. long. The flowers 

 are about 10 mm. wide, in smooth corymbs; calyx-lobes smooth, triangular, pointed, 

 red-tipped; stamens about 20; anthers small, yellow; styles 3 to 5. The fruit 

 ripens in August, is globose, about 8 mm. thick, blue-black, its calyx-lobes re- 

 flexed, persistent; flesh yellow, thin and sweet; it contains 3 to 5 nutlets, cormnonly 

 5, 3.5 to 4 mm. long, the nest of nutlets 5 to 5.5 mm. thick; nutlets ear-shaped, 

 slightly ridged on the back, with a calyx-scar, iimer surface roughened with shallow 

 pits. 



