126 



THE CACTACEAE. 



Series 7. TORTISPINAE. 



Prostrate 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 of this series, at the New 

 York Botanical Garden. 



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. 0. allairci 



Fruit 5 to 7 cm. long ... . n6a. O. lata 



Fruit obovoid; joints turgid.. . 117. 0. pollardii 



Joints green; roots not tuberous. 

 Flowers 8 cm. broad or less. 



Joints orbicular or little longer than wide . 1 18. 0. apniilia 



Joints oblong, much longer than wide ... . 1 19. 0. macmrthra 



Flowers 10 to 12 cm. broad 



Spines mostly 2 or more at an areole. 

 Ovary obconic, 2 to 4 cm. long. 

 Roots tuberous. 



Joints repand ; plant suberect .121. 



Joints scarcely icpand; plants nearly prostrate. . .122. 



Roots not tuberous. 



Flowers and fruit small . 123. 0. plitmbea 



Flowers and fruit large. 



Spines white to light brown, slender. 



Seeds acute-margined . 124. O. tortispina 



Seeds obtuse-margined. 



Fruit large, 4 to 5 cm. long; spines light colored. ... 125. 0. stenochila 



1 20. O. grand i 'flora 



O. aiistrina 

 0. macrorhiza 



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



126. O. delicata 



Spines dark brown, stout. . .127. 



Ovary narrowly subcylindric, 5 to 6 cm. long. . 1270. 



: 83. 1909. 



O. fiiscoalra 

 0. macalcei 



FIG. 158. Opuntia 

 allairei. Xo.66. 



116. Opuntia allairei Griffiths, Rep. Mo. Bot. Card. 20 



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. 



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. Card. 20: pi. 

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



Figure 158 is copied from the second illus- 

 tration above cited. 



116a. Opuntia lata Small, Journ. N.iY. r Bot. Card. 

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



117. Opuntia pollardii Britton and Rose, Smiths. Misc. Coll. 50: 523. 1908. 



Prostrate, tuberiferous, related to Opuntia opuntia; young joints bluish green, glaucous, 5 to 16 

 cm. long, i to 2 cm. thick; areoles 1.5 to 3 cm. apart, bearing numerous yellow glochids 2 to 3 cm. 



FIG. 159. Opuntia pollardii. Xo-4- 



