192 



ESSENTIALS OF BOTANY 



American sand-box tree bursts open when thoroughly dry 

 with a noise like that of a pistol shot. 



237. Winged or Tufted Fruits and Seeds. — The fruits 

 of the ash, box-elder, elm, maple (Fig. 139), and many 

 other trees are provided with an expanded membranous 

 wing. Some seeds, as those of the catalpa and the trum- 

 pet^creeper, are similarly appendaged. The fruits of the 

 dandelion, the thistle, the fleabane, and many other plants 



of the group to which 

 these belong, and the 

 seeds of the willow, 

 the milkweed {Ascle- 

 pias), the willow-herb, 

 and other plants bear 

 a tuft of hairs. 



The student should be 

 able, from his own ob- 

 servations on tlie falling 

 fruits of some of the trees 

 and other plants above 

 mentioned, to answer 

 Pig. 143. Fruitsof Linden, withaBract joined ^"'^^ questions as the 

 to the Peduncle and forming a Wing. following. 



What is the use of the 

 wing-like appendages? of the tufts of hairs? 



"Which set of contrivances seems to be the more successful of the 

 two in securing this object? 



What particular jilant of the ones available for study seems to 

 have attained this object most perfectly? 



AYhat is one reason why many plants with tufted fruits, such as 

 the thistle and the dandelion, are extremely troviblesome weeds ? 



A few simple experiments, easily devised by the student, may help 

 him to find answers to the questions above given.' 



1 See Kerner and Oliver, Vol. II, pp. 833-875; also Seal's Seed Dispersal. 



