CATAPULT AND SLING FRUITS 



escape. Small holes appear in it, or the fruit splits. As the 

 dry, elastic, withered stalk swings to and fro in the wind, 

 the seeds are swung out of these openings, and starting with 

 a certain momentum the wind will carry them often to a 

 surprising distance from their parents. In wet or rainy 

 weather these holes or slits generally close together, and no 

 seeds are sent forth on their travels. The little holes in the 

 top of a poppy-head by which the seeds are swung out 

 have little flaps, which close over and shut them up in wet 

 weather. ' 



Some plants make a sort of catapult to sling or hurl their 

 fruits. Kerner von Marilaun was the first to describe some 

 of these curious arrangements. He had brought home some 

 fruits of Dorycnium herbaceum and laid them on his writing- 

 table. " Next day as I sat reading near the table, one of 

 the seeds of the Dorycnium was suddenly jerked with great 

 violence into my face." Some of the neatest catapult fruits 

 are those of Teucrium Jlavum. (There is a British species, 

 the Woodsage, but it has not got the same arrangement.) 

 When the petals have fallen off, the four small fruits are left 

 inside the cup-like sepals ; the flower-stalk when dry is very 

 elastic, and if an animal touches the sepals it swings violently 

 and shoots out one of the fruits. But that is by no means 

 the whole of the process : there are hairs arranged spirally in 

 the throat of the sepals, and these give a spin or twirling 

 motion like that of a rifle-bullet to the fruit. The fruit also 

 flies out of the sepals in a line of flight which is inclined at 

 an angle of about forty-five degrees to the horizon ; at this 

 angle, as is well known, the trajectory or distance travelled 

 will be the greatest possible. 



But by far the best way to understand these questions is 

 to try with some common weeds in the country towards 



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