FLOWER STRUCTURE 



193 



PLATE 64. Flower Structure. 



Powdered Arnica Flowers. 1. Pollen grain. 2. Glandular trichome (unicellu- 

 lar). 3. Glandular trichome (multicellular). 4. Nonglandular trichome (unicellu- 

 lar). 5. Nonglandular trichome (multicellular). 6. Nonglandular trichome (mul- 

 tiseriate). 7. Stamen tissue. 8. Stigma tissue, showing papillae. 9. Nonglandu- 

 lar trichome (bicellular). 10. Petal tissue. 11. Petal tissue, showing spiral vessel. 

 12. Calyx tissue. 



