470 



HUTCHINSON'S POPULAR BOTANY 



the fruit severs itself from the stalk, and instantly the seeds are squirted 

 out in a fountain of pulp through the unprotected hole. In the Touch- 

 me-not Balsam (Impatiena noli-me-tangere, fig. 577) the five divisions of 

 the capsule leap from the stalk when the seeds are ripe, and, twisting 

 suddenly up, get rid of their offspring in a very summary manner. 



The Common Dandelion (Taraxacum officinale, fig. 573) offers the most 

 familiar example of the dispersal of plumed fruits by means of the wind. 

 Each of its white downy balls, "the schoolboy's clock in every town," is 

 an aggregation of such fruits, waiting for the first breeze to scatter them. 

 The beauty of these tiny parachutes, and the gracefulness of their motion 

 as they float through the summer air, cannot be too greatly admired. The 

 Tillandsias, many of which are epiphytes, have plumed fruits which are 



specially adapted for 

 anchoring them to the 

 bark of old trees, where 

 they are able to ger- 

 minate immediately. 

 In Cirs^^lm nemo-rale, 

 one of the Plume This- 

 tles, the fruits just 

 break away from their 

 sessile plumes and fall 

 to the ground, when- 

 ever an obstacle is en- 

 countered in the course 

 of flight. Doubtless 

 the obstacle gives suf- 

 ficient promise of terra 

 firrna below to encour- 

 age them thus to slip 

 their parachutes and 

 risk a descent. 



Creeping fruits are 

 characterized by their stiff bristles, which are peculiarly sensitive to mois- 

 ture. As a result of this sensitiveness, the fruits continually change their 

 position, and are able to propel themselves along in a definite direction, a 

 hygroscopic arrangement which enables them to be carried long distances. 



Even jumping fruits are not unknown. Insect activity within the fruit 

 is the cause of the phenomenon, and one of its effects is undoubtedly the 

 dispersion of the seeds. Two plants are known which have so-called 

 "jumping beans'" viz., Sebastiania palmeri and S. bilocularis; and the 

 insects which cause the motion are Carpocapsa saltitans in the former, 

 and Grapholitha sebastiania in the latter. Sebastiania palmeri is a very 

 peculiar tree. It was discovered not many years since in a morass, half 



FIG. 577. TOUCH-ME-NOT BALSAM (Impatiena noli-me-tctngere) 



EXPELLING ITS SEEDS. 



