THE ANGIOSPERMAE 



1511 



dries at maturity and the curvature of the fibres causes the carpels to snap 

 apart. In Hevea each carpel then opens loculicidally, the two halves 

 separating suddenly, with a twist, which ejects the single large seed. The 

 seeds of Hevea are an inch long but they fly as much as 40 yds. from big 

 trees, partly burying themselves in soft ground (Fig. 1380). 



Two examples of explosive soft fruits are well known and very striking. 

 One is Impatiens, species of which are known as Balsams. They are large 

 herbs usually growing near water. The five carpels are joined into a 



Fig. I -58 1. — k^Gercwiiini palustre. tljection of seeds. (See also Fig. 

 1 378.) R, hnpntiens noli-tangere. Mechanical ejection of seeds. 

 Sec in text. (After Kerner and Oliver.) 



cylindrical fruit, swollen at its upper end, where the seeds are. Tension 

 is set up by a lining layer of large turgid cells and when the fruits are ripe 

 any slight disturbance causes the carpels to break apart and roll up inwards, 

 throwing off the seed in all directions. The seeds often fall into the water 

 and are further distributed by floating, though they are only ejected to a 

 few yards distance (Fig. 1381). 



