62 THE FRUIT OF OPUNTIA FULGIDA. 



Plate 10. Photographs of O. discata, 0. cylixdrica, O. leptocaclis, and 

 o. catacantha. 



Fig. 87. Portion of joint of O. discata bearing a gall fruit with projecting pupa cases 



from which the cactus flies have just escaped. X 0.45. 

 Fig. 88. Tip of a joint-fruit of 0. cylindrica of 1913, bearing a persistent fruit of 1914, 



two flowers and a vegetative joint of 1915. Note constriction only, 



instead of the usual distinct articulation at base of the parent fruits. 



X 0.45. 

 Fig. 89, a, b, c. Three branches of 0. leptocaulis bearing fertile fruits of 1914, sterile 



fruits, various forms of more or less fruit-like branches, and also (c) 



flower buds for 1915. X 0.45. 

 Fig. 90. A single joint of O. catacantha bearing four chains of fruits (all sterile), 



showing one chain of six links on right and a single open flower on left. 



Collected at St. Thomas, Virgin Islands, May 1915. X 0.45. 

 Fig. 91. Series of fruits of 0. catacantha (from same collection as those in figure 90) 



in surface view, also in longitudinal and transverse section, showing 



perianth-scar and small sterile ovarian cavity. X 0.45. 



Plate 11. Photographs of Peireskia, Opuntia rxjfida, 0. arbuscula, and 

 O. leptocaulis. 



Fig. 92. Two generations of flowers of Peireskia guamacho, showing proliferation 

 of primary flower from axillary buds at the level of the ovarian cavity 

 (indicated by an x). The primary flower and the secondary one at 

 right are shown in median longitudinal section. X 0.6. 



Fig. 93. Flower and fruit of Peireskia guamacho, showing umbilicate fleshy fruit 

 with areole on right side above. X 0.9. 



Fig. 94. A joint of 0. rufida bearing three persistent fruits, from one of which a new 

 vegetative joint has arisen. X 0.45. 



Fig. 95. Two lower branches of 0. arbuscula bearing persistent fruits, and these, as 

 well as the normal vegetative joints, bearing slender condensed shoots 

 with closely packed areoles. X 0.45. 



Fig. 96. Branch of 0. leptocaulis showing fruits and fruit-like branches, like those 

 described for figure 89. X 0.45. 



Plate 12. Drawings of O. fulgida. 



Fig. 97. Tangential section of half-grown seed, perpendicular to the flattened sides of 

 seed and passing through micropyle, showing pocket of funiculus which 

 incloses the seed and the two integuments. X 95. 



Fig. 98. Section of ripe seed in plant of greatest diameter, showing embryo, endo- 

 sperm, integuments, and thick wall of funicular pouch with its included 

 vascular bundle. X 17. 



Fig. 99. Longitudinal section of a fruit which has given rise to a new plantlet, show- 

 ing the portion of the fruit cut off by a layer of cork from participation 

 in the new plant. X 1.33. 



Fig. 100. Longitudinal section of a fallen fruit through the point of origin of an 

 adventitious root from the border of an areole. X 14. 



