DESCRIPTION OF PLATES. 



FKOOTISPIECE. 



Cactus Grove in Arizona (Cereus giganteus, Engelui.). 



PLATE I. 



Canotia nOLACANTHA, Torr. — Branch natural size. Fig. 1. Cross-section of flower. Fig. 2. 

 Open flower. Fig. 3. Vertical section of flower. Fig. 4. Inside view of stamen. Fig. 5. Outside view 

 of stamen. Fig. 6. Flower with petals gone, but filaments persisting. Fig. 7. Vertical section through 

 young ovary. Fig. 8. Ovule. Fig. 9. Vertical section through mature ovary. Fig. 10. Cross-section 

 through ovary. Fig. 11. Seed. Fig. 12. Diagonal section through seed. Enlarged 4-5 diameters. 



PLATE II. 



A. Parryella filifolia, T. & G.— Branch natural size. Fig. 1. Flower. Fig. 2. Vertical sec- 

 tion through flower. Fig. 3. Tube of stamens, laid open. Figs. 1, 2, and 3 enlarged 10 diameters. Fig. 

 4. Mature legume. Fig. 5. Longitudinal section through Fig. 4, and both enlarged 5 diameters. 



B. Petalostemon tenuifolius, Gray. — Somewhat reduced. Fig. G. Bract. Fig. 7. Flower. 

 Fig. 8. Flower seen from above, with the four petals on the column of stamens and the fifth on the 

 calyx. Fig. 9. Section through the pod. All enlarged about 10 diameters. 



PLATE III. 



A. Horkelia purpurascens, Watson.— Natural size. Fig. 1. Flower-bud. Fig. 2. Expanded 

 flower. Fig. 3. Calyx, spread open. All enlarged about 4 diameters. 



B. Potentilla Wheeleri, Watson. — Somewhat reduced. Fig. 4. Flower, Been from above. 

 Fig. 5. Flower, seen from below. Fig. 6. Vertical section through flower. All enlarged about 5 diam- 

 eters. Fig. 7. Single pistil, enlarged about 10 diameters. 



PLATE IV. 



PETAiONYX nitidus, Watson. — Fig. 1. Branch natural size. Fig. 2. Flower. Fig. 3. Petal. 

 Fig. 4. Diagonal section through calyx and ovary, showing tho single suspended ovule. All enlarged. 



Fig. 6. Branch of Viguiera reticulata, Watson.— Natural size. Fig. 7. Disk-flower, enlarged 

 20 times. Fig. 8. Chaff of disk-flower, enlarged 20 times. Fig. 9. Ray-flower, enlarged 20 times. Fig. 

 10. Section through naked receptacle, enlarged 10 times. 



PLATE V. 



Brickeiaia 1-Ongifoi.ia, Watson. — Branch nearly natural size. Fig. 1. Head of flowers, enlarged 

 8-10 times. Fig. 2. Single flower, enlarged 12 times. Fig. 3. Style and stigma, enlarged 12 times. 

 Fig. 4. Receptacle and involucre, enlarged 12 times. Fig. 5. Aehcnium and pappus, enlarged 12 diam- 

 ters. Fig. G. Single bristle of pappus, enlarged 20 times. 



26 BOT 401 



