" i 



126 



TH^ CACTAC^A^. 



Series 7. TORTISPINAE. 



Trostrate or spreading plants rarely erect, with mostly rather small, persistent, scarcely tuber- 

 culate, orbicular or oval joints, and large flowers; natives of the eastern, central, and southern 

 United States. 



Plate 21 represents a group of hardy cacti, chiefly species o£ this series, at the New 



York Botanical Garden. 



i 



Key to Species. 



Spines none or only i or 2 at an areole. 



Joints bluish green; at least when young; roots tuber-like. 

 Fruit clavate; joints thin. 



Fruit about 4.5 cm. long 116. 



Fruit 5 to 7 cm. long ii6a. 



Fruit obovoid; joints turgid 1 1?- 



Joints green; roots not tuberous. 

 Flowers 8 cm. broad or less. 



0. all air ci 



0. lata 



0. pollardii 



0. opuntia 

 0. macrarthra 



0. austrina 

 0, macrorhiza 



0. stenochila 

 0. delicata 

 0. fuscoatra 

 0. macateei 



Joints orbicular or little longer than wide 118. 



Joints oblong, much longer than wide 119- 



Flowers 10 to 12 cm, broad 120. 0. grandiflora 



Spines mostly 2 or more at an areole. 

 Ovary obconic, 2 to 4 cm. long. 

 Roots tuberous. 



Joints repand; plant suberect 121. 



Joints scarcely lepand; plants nearly prostrate 122. 



Roots not tuberous. 



Flowers and fruit small 1 23. 0. plumbea 



Flowers and fruit large. 



Spines white to light brown, slender. ' • ^ 



Seeds acute-margined 124. 0. tortispina 



Seeds obtuse-margined. 



Fruit large, 4 to 5 cm. long; spines light colored. . . . 125. 

 Fruit small, 2 to 3 cm. long; spines brown. ........ 126. 



Spines dark brown, stout :..... 127. 



Ovary narrowly subcylindric, 5 to 6 cm. long : 127a. 



M 



116. Opuntia allairei Griffiths, Rep. Mo. Bot. Gard. 20: 83. 1909. 



A low, spreading, tuberous-rooted, prostrate 

 plant, with some of the joints ascending; joints 

 bluish green, obovate, usually 10 to 15 cm. long, 

 originally described as even longer, with or without 

 spines; spines, if present, i to 3, yellowish brown, 

 2,5 cm. long or less, slender but a little flattened; 

 glochids numerous, especially abundant at very old 

 areoles, yellow; leaves 6 to 8 mm. long; flowers 

 6 to 7 cm, broad, yellow with a red center; fruit 4 to 

 5 cm. long, dark red. 



Type locality: Mouth of Trinity River, 

 Texas. * 



^ . 



.1 -i 



^ 



Fig. 158. 



allairei. 



Opuntia 

 X0.66. 



^ ■- 



L ^ 



Distribution: Southern Texas and western 

 Louisiana. : • . 



This species is perhaps nearest 0. macror- 

 hiza, but differs in the usual absence of spines 

 and in differently colored joints. 



Illustrations: Rep. Mo. Bot. Gard. 20: pi. 

 2, f. 2; pi. 5; pi. 12, in part. 



Figure 158 is copied from the second illus- 

 tration above cited. 



/ 117 



}untia lata Small, Journ. N. Y.^Bot. Gard. 

 20: 26. 1919. (See Appendix, p. 220.) 



juntia pollardii Britton and Rose, Smiths. Misc 



:i' 



4 





->- 



Fig. 159. — Opuntia pollardii. X0.4. 



li. so: 523. 1908. 



cm. 



opuntia; young joints bluish green 

 apart, bearing numerous yellow z 



