feOME PLANT BlOGilAPHiEB. 209 



a second arrow-shaped appendage. No ant ever 

 gets beyond the third or fourth barricade ; the 

 device is efficient : the vetch thus offers black- 

 mail to creeping thieves in the shape of stem- 

 honey, in order to guard from their depredations 

 the far more valuable and useful honey in the 

 flowers, which is intended to attract the fertilising 

 insects. 



When the purple flowers have in due time 

 been fertilised, they produce long narrow pods, 

 each containing about a dozen round pea-like 

 seeds. As the pods ripen, the plant shrivels up, 

 and usually dies away, leaving only the ripe 

 seeds to represent its kind through the winter. 

 But sometimes, in damp and luxuriant autumns, 

 the stem struggles through the winter to a second 

 season, and flowers again in the succeeding 

 summer. We express this fact as a rule by 

 saying that the vetch is usually an annual, but 

 occasionally a biennial. 



With most annuals, such as wheat or sun- 

 flower, the whole strength of the plant is used 

 up in the production of seed ; and as soon as 

 the seed is set, the plant dies immediately. 

 Where annuals have the sexes on separate 

 plants, however, the male plants die as soon 

 as they have shed their pollen, their task 

 being thus complete ; while the females live on 

 till their seed has ripened. 



Common coltsfoot is another well-known plant 

 whose life-history shows some points of great 

 interest. It grows in the first instance from 

 a feathery fruit, one-seeded and seed-like, which 

 is carried by the wind, often from a great 



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