46 THE TREE BOOK 



tall between -tliein. The .stamens are so ar- 

 ranged that they are sure to rub against the 

 back of any visiting insect. And, on the first 

 day of the flower's life, when the pollen from 

 the stamens is eager to be gone, the pistil stands 

 with its two funny little arms pressed together 

 and raised upright, carefully coveiing itself so 

 that it may not be fertilized by the stamens 

 in the same blossom. By the second day, 

 usually, the many insects which love the catalpa 

 have carried off the pollen from these particu- 

 lar stamens, and they stand empty, dry emd 

 brown. Then the pistil lowers its arms and 

 bends forward, bringing its sticky tip into the 

 mouth of the blossom cup. Here it is in fine 

 position to rub against the coat of the bee, com- 

 ing in all dusty with the pollen frona another 

 blossom. 'Nor does the visitor have to prospect 

 for his reward! A little groove in the center 

 of the lower lip is carefully outlined with 

 streaks of yellow to catch his eye, and a tiny 

 passage nicely adapted to fit his proboscis leads 

 straight to the nectar. 



If by chance a bee stumbles in where there is 

 no need of his services, he knows it instantly, 

 for the yellow marking the "refreshment 

 istand" is tinged to tawny yellow, and says 

 plainly: "Nectar gone; flower fertilized." 



