192 ELEMENTS OF BOTANY 
American sand-box tree bursts open when thoroughly dry 
with a noise lke 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 (Plate 
XJ), the willow-herb, 
and other plants bear 
a tuft of hairs. 
Aw 
The student should be 
able, from his own ob- 
servations on the falling 
fruits of some of the trees 
and other plants above 
mentioned, to answer 
Fia. 143. Fruits of Linden, witha Bract joined such 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 particulia plant of the ones available for study seems to 
have attained this object most perfectly ? 
What is one reason why many plants with tufted fruits, such as 
the thistle and the dandelion, are extremely troublesome 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. I], pp. 838-875; also Beal’s Seed Dispersal. 
