ILLUSTRATIONS. 



Plate i 

 Plate 2 



Plate 3 



Plate 4 



Plate 5 

 Plate 6 



Plate 7. 



Plate 8 



Plate 9 



Plate 10 

 Plate ii 



Plate 12 

 Plate 13 



Plate 14 



Plate 15 



Plate 16 



Plate 17 



Plate 18 



Plate 19. 



Plate 20. 

 Plate 21. 

 Plate 22. 



Plate 23. 



Plate 24. 

 Plate 25. 



Plate 26. 



Plate 27. 



Plate 28. 



Plate 29. 

 Plate 30. 

 Plate 3 1 . 

 Plate 32. 



Plate 33- 



Plate 34- 



Plate 35- 



Plate 36. 



FACING 



PLATES PAGE 



Cactus Desert in Arizona Frontispiece 



i) Flowering branch of Pereslda pereskia. (2 and 3) Fruit of Pereskia pereskia. (4) Leaf y branch of 



Pereskia sacharosa (5) Proliferous fruit of Pereskia sacharosa 10 



i) Flowering branch of Pereskia grandifolia. (2) Leafy branch of Pereskiopsis chapistle. (3) Leaf}- 



branch of Pereskiopsis pititache 20 



i) L'pper part of flowering joint of Nopalea cocheniUifera. (2) Upper part of flowering joint of 



Xopalea auberi. (3) Fruit of Nopalea auberi. (4) Flowering joint of Nopalea dejecta 34 



Nopalea auberi as it grows near Mitla, Mexico 38 



I and 2) Branch of Opuntia mortolensis. (3 and 4) Branch of Opuntialeptocaulis. (5) Flowering 



branch of Opuntia arbuscula. (6) Flowering branch of Opuntia kleiniae 48 



i) Leafy branch of Opuntia kleiniae. (2) Terminal branch of Opuntia vivipara. (3) Branch of 



Opuntia panri. (4) Flowering branch of Oprmtia echinocarpa. (5) Fruiting branch of 



Opuntia versicolor 50 



i) Type plant of Opuntia \d\'ipara, near Tucson, Arizona. (2) A much branched plant of Opuntia 



versicolor 52 



i) Joint of Opuntia tetracantha. (2, 3, 4, 5) Flowering joint of Opuntia versicolor. (6) Prohferous 



fruits of Opuntia fulgida 54 



i) Joint of Opuntia tunicata. .(2, 3, 4, 5) Joint of Opuntia spinosior 66 



i) Leafy branch of Opuntia imbricata. (2) Flowering branch of Opuntia proUfera. (3, 4) Form of 



Opuntia alcahes. (5, 6) Opuntia vestita 68 



i) Clump of plants of Opuntia fulgida. (2) A very open plant of Opuntia spinosior 70 



i) Opuntia exaltata as seen in the highlands of Peru. (2) Clump of Oprmtia floccosa as it grows in 



the valleys of the Andes of eastern Peru 76 



i) Flowering branch of Opuntia burrageana. (2) Opuntia cylindrica. (3, 4) Joint of Opuntia stanlji. 



(5) Flowering joint of Opuntia macrorhiza 78 



I, 2) Part of joint of Opuntia exaltata. (3) L'pper part of joint of Opuntia macrarthra. (4) L'pper 



part of joint of Opuntia tortispina 80 



i) Top of Opuntia miquehi. (2) Old and young joints of Optmtia inNicta. (3) L'pper part of joint 



of Opuntia iguescens 98 



i) Joint of Opuntia pascoensis. (2) Joints of Opuntia taj-lori. (3, 4) Form of Opuntia repens. 



(5) Flower of Opuntia repens. (6) Flowering joint of Opuntia drummondii 102 



i) Two plants of Opuntia drummondii. (2) Joints of Opuntia retrorsa with flower. (3) Joints of 



Opuntia triacantha. (4) Joint of Opuntia jamaicensis. (5) Section of fruit of Opuntia 



jamaicensis 104 



i) Plant of Opuntia jamaicensis. (2, 3) Flower of Opuntia jamaicensis. (4) Longitudinal section 



of flower of Opuntia jamaicensis. (5, 6) Stamen of Opimtia jamaicensis. (7) Style of 



Opuntia jamaicensis 112 



i) Flowering joint of Opuntia decumbens. (2) Fruiting joint of Opuntia decumbens. (3) H3-brid 116 

 Group of hardy Optmtia, mosti}- Opuntia tortispina, in groimds of New York Botanical Garden . ... 126 

 i) Joints of Opuntia microdasys. (2) Flowering joint of Opuntia macrarthra. (3) Fruit of Opuntia 



macrarthra. (4) Seed of Opimtia macrarthra. (5) Flowering joint of Opuntia opuntia 128 



i) Flowering joint of Opuntia fuscoatra. (2) L'pper part of joint of Opuntia sulphiu'ea. (3) Joint 



of Opuntia tenmspina 132 



i) Plant of Opuntia santa-rita. (2) Plant of Opuntia discata 142 



i) Flowering joint of Opuntia atrispina. (2) Flowering joint of Opuntia phaeacantha. (3) Upper 



part of joint of Opuntia engelmanrui 144 



i) Flowering joint of Opuntia bergeriana. (2) Flowering joint of Opuntia elatior. (3) Flowering 



joint of Opuntia boldinghii. (4, 5) Joint of Opimtia data 152 



i) L^pper part of fruiting joint of Opuntia schumannii. (2) Flower of Opuntia schumannii. (3) 



Flowering joint of Opuntia Aiilgaris. (4) Flowering joint of Opuntia stricta 156 



i) Flowering joint of Opuntia lae\'is. (2) Flowering joint of Opuntia dillenii. (3) L'pper part of 



flowering joint of Opimtia aciculata 160 



i) View of Opuntia keyensis. (2) View of Opuntia dillenii 162 



Flowering joint of Opuntia linguif ormis 1 64 



Flowering joints of Opuntia hndheimeri. (i) Orange-flowered race. (2) Red-flowered race 166 



i) L'pper part of flowering joint of Opuntia leptocarpa. (2) Fruit of Opuntia leptocarpa. (3) Flower- 

 ing joint of Opuntia velutina. (4) L'pper part of joint of Opuntia megacantha 172 



i) L'pper part of joint of Opuntia tomentosa. (2) Flowering joint of Opuntia brasiUensis. (3) 



Flowering branch of Opuntia brasiUensis. (4) Joint of Grusonia bradtiana 174 



i) Part of joint of Opuntia leucotricha. (2) Part of joint of Opimtia maxima. (3) Joint of Opuntia 



lasiacantha. (4) Joint of Opuntia robusta i So 



i) Plant of Opuntia fragilis. (.2) Flowering branch of Opuntia rhodantha. (3) Flowering joint of 



Opuntia polyacantha 194 



i) Flowering joint of Opuntia spinosissima. (2, 3) Single flower of Opuntia spiuosissima. (4, 5) 



Longitudinal section of flower of Opuntia spinosissima. (6) Cross-section of ovarj' of 



Opuntia spinosissima. (7) Style of Opuntia spinosissima 204 



