THE FRUIT OF OPUNTTA FULGIDA. 61 



Fig. 70. Transverse section of a two-year vegetative joint, at about 2 centimeters 

 above base, showing vascular bundles and the radiate arrangement of 

 the palisade tissues in each tubercle. (Cf. figures 39 and 43.) X 1.5. 



Fig. 71. Part of transverse section of tubercle of an unopened flower, showing epi- 

 dermis, stomata and palisade with its intercellular air spaces. X 205. 



Fig. 72. Small portion of transverse section of two or three year old fruit, showing 

 details of stomata of the epidermis and its thick-walled underlying 

 layers. X 365. 



Fig. 73. Small portion of transverse section of tubercle of similar fruit, showing 

 resemblance of the palisade, etc., to that of the vegetative joint. (C/. 

 figure 69.) X 110. 



Fig. 74. Part of tangential section of tubercle of a two-year vegetative joint, showing 

 palisade cells and mucilage cells in cross-section. X 85. 



Fig. 75. Section of one of the crystal-holding cells so abundant in the subepidermal 

 and parenchymatous tissues. X 365. 



Plate 8. Photographs 76 to 79, O. fulgida; 80, Callistemon; 81, O. versicolor. 



Fig. 76. Lateral view of a five months' seedling, showing hypocotyl, cotyledons, and 



first joint of stem. Seed planted April 27, 1917; photograph of living 



seedling made October 12 following. X 0.9. 

 Fig. 77. Part of a cluster of fruits collected at Tucson in April 1915, showing one 



chain of 14 links in a single linear series. X 0.3. 

 Fig. 78. Plantlet 10 months old, developed in a greenhouse in Baltimore from a fallen 



fruit, showing position of adventitious roots and structure of the new 



shoots. X 0.66. 

 Fig. 79. One of the two examples found in which the persistent fruits of 0. fulgida, 



while still attached, proliferate to vegetative branches. Collected and 



photographed at Tucson in April 1915. X 0.45. 

 Fig. 80. Branch of Callistemon speciosum, with three generations of flowers and 



fruits, showing the persistence and growth of the firm green capsules. 



Flowers at the tip about to open. Collected on the campus of the Uni- 

 versity of California in March 1916. X 0.23. 

 B^G. 81. Gall fruit of 0. versicolor. Collected and photographed at Tucson in April 



1915, showing the curling of the abortive petals and the fly Asphondylia, 



which has just escaped from one of the pupa cases projecting from the 



side of the gall below the fly. X 0.3. 



Plate 9. Photographs of O. versicolor. 



Fig. 82. A branch of 0. versicolor bearing several clusters of fruits and galls of 1914, 

 and groups of flower buds of 1915. Some of fruit-like structures are 

 clearly galls, but others are nearly, if not quite, normal. Collected and 

 photographed at Tucson, May 1915. X 0.45. 



Fig. 83. A piece of a vegetative joint of 0. versicolor collected at Tucson in April 

 1915, showing 3 types of persistent fruits or galls. X 0.6. 



Fig. 84. Four types of gall fruits of 0. versicolor, showing, at left, a slightly devel- 

 oped perianth; and, at right, a very highly developed perianth. Col- 

 lected and photographed at Tucson in April 1915. X 0.45. 



Fig. 85. Branch of 0. versicolor with two galls of 1913 or 1914. One of these bearing 

 two vegetative branches developed in 1914, and each of these a cluster of 

 flower buds for 1915. Collected and photographed at Tucson in May 

 1915. X 0.45. 



Fig. 86. Branch of 0. versicolor, showing persistent fruit (normal?) bearing a vege- 

 tative branch which is directed backward toward base of the parent 

 branch. Tucson, April 1915. X 0.45. 



