OPUNTIA. 



99 



Plate xvi, figure 3, represents old and young joints of the plant collected above Ay- 

 rampl, Peru, by Dr. Rose in 1914. Figure nS shows a fruit from thesame plant ;figure 119 

 is from a photograph taken by H. L. Tucker at Coropuna, Peru, in 1911. 



75. Opuntia campestris sp. nov. 



Much branched, often forming low, dense masses, 3 to 6 dm. in diameter; terminal joints readily 

 breaking off; joints globular or a little longer than thick, 3 to 5 cm. long, with numerous prominent 

 areoles, the tubercles conspicuous when young; leaves minute, i to 1.5 mm. long, caducous; glochids 

 conspicuous, numerous, yellow; spines usually wanting at the lower areoles, present above, very 

 unequal, 5 to 10, acicular, the longest ones 3.5 cm. long; flowers rosy white to light yellow, 2 to 3 cm. 

 long; ovary naked or spiny; fruit thicker than long, 2.5 cm. long, with deep umbilicus, often very 

 spiny. 



Common just below railroad station at 

 Pampa de Arrieros, Peru, where it was col- 

 lected by Dr. Rose, August 23, 1914 (No. 18957). 

 Figure 120 represents joints of the type 

 specimen above cited. 



FIG. 120. Opuntia campestris. Xo.8. 



FIG. 121. Opuntia ignota. Xo.8. 



76. Opuntia ignota sp. nov. 



Low, much branched, spreading; joints small, narrow, 2 to 3 cm. long, more or less purplish; 

 leaves minute, often purplish; spines 2 to 7 from an areole, brownish, acicular, the longest ones 4 to 

 5 cm. long; glochids, when present, yellow; areoles large, full of grayish wool; flowers and fruit not 



seen. 



Collected by Dr. Rose on the hills below the railroad station at Pampa de Arrieros, 

 Peru, August 23, 1914 (No. 18974). 



Plants grown in greenhouses are dark green and develop few spines or none. 

 This plant grows in the same region as 0. campestris, but is quite different from it. 

 Figure 121 shows joints of the type specimen above cited. 



Subgenus 3. PLATYOPUNTIA. 



Includes all the species with flattened joints ; a few species have nearly terete joints ; 

 others have some of the joints terete. Twenty-eight series are recognized. The species 

 are most abundant in North America, but several series are found only in South America, 

 while others have representatives in both Americas. (See Key to the Series, p. 45.) 



