DESCRIPTION OF PLATES. 



FBONTISPIECE. 



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



PLATE I. 



Canotia holacantha, 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. Outride 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. Pakryella fllifolia, 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 tenuieolius, Gray. — Somewhat reduced. Fig. 6. 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, seen 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. 



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

 Fig. 4. Diagonal section through calyx and ovary, showing the 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. 



Brickellia LONGIPOLIA, 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. Eeceptacle and involucre, enlarged 12 times. Fig. 5. Achenium and pappus, enlarged 12 diam- 

 ters. Fig. 6. Single bristle of pappus, enlarged 20 times. 



26 BOT 401 



