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PUBLIC HEALTH BULLETIN NO. 286 



37. Plants white-powdery above; plants extremely large, Thalia, p. 111. 



usually over 1 m. (fig. 33). 

 37. Plants smaller; not white-powdery above 38. 



38. Petiole often very short; leaves shed water Orontium, p. 102. 



easily; flowers along fleshy spike enclosed 



in a leafy sheath (fig. 34). 

 38. Petioles long; flowers and leaves not as above. 39. 



39. Flowers many; leaves large, over 10 cm. long (fig. 35). Pontederia, p. 107. 

 39. Flowers solitary; leaves small, less than 5 cm. long Heteranthera, p. 106. 

 (fig. 36). 



x'/6 



Figure 35. 



Figure 36. 



