FLOWERS AND THEIR WORK 



39 



insect-visited flowers, and discovered in almost every case that 

 showy, sweet-scented, or otherwise attractive flowers were adapted 

 or fitted to be cross-pollinated by insects. He also found that, in 

 the case of flowers that were inconspicuous in appearance, often a 

 compensation appeared in the odor which rendered them at- 

 tractive to certain insects. The so-called carrion flowers, pol- 

 linated by flies, are examples, the odor 

 in this case being like decayed flesh. 

 Other flowers open at night, are white, 

 and provided with a powerful scent so 

 as to attract night-flying moths and 

 other insects. Flowers adapted to 

 be cross-pollinated by insects are fre- 

 quently irregular in shape. Thus 

 butter and eggs is a flower which is 

 well fitted for cross-polhnation by in- 

 sects. 



-. ^ Butter and . FfEC (Linaria linaria). — 

 From July to October this very abundant 

 weed may be found especially along road- 

 sides and in sunny fields. The flower 

 cluster forms a tall and conspicuous flower 

 cluster known as a spike, the yellow and 

 orange flowers being arranged so that they 

 come out directly from the main flower 

 stalk. 



The corolla projects into a spur on the 

 lower side ; an upper two-parted lip shuts 

 down upon a lower three-parted lip. The 

 four stamens are in pairs, two long and two short. (The stamens of 

 two lengths are so placed that they may allow self-pollination in stormy 

 weather, when insects faU to reach the flower. The instructor should 

 explain this.) 



Certain parts of the corolla are more brightly colored than the 

 rest of the flower. This color is a guide to insects. Butter and eggs 

 is visited most by bumblebees, which are guided by the orange lip to 

 alight just where they can push their way into the flower. The bee, 

 seeking the nectar secreted in the spur, brushes his head and shoulders 

 against the stamens. Visiting another flower of the cluster, it would 

 be an easy matter accidentally to transfer this pollen to the stigma of 

 another flower. In this way cross-pollination is effected. 



Spike of butter and eggs 

 {linaria). 



