CATAPULT FRUITS. 



841 



^exh^ts the following arrangement: The receptacle is LSte oT pal*^ 

 the mvolucra scales form a sort of basket at the bottom of which are th Tn 

 In damp weather the tips of the bract-scales close tightly together, and the 

 bnstles of the pappus crowning each fruit are applied closely to one another. In 

 warm, dry weather espec.ally, under the influence of a dry wind and sunshine the 

 scales part asunder and the basket stands wide open. At the same time the hat 



10 



1 and 2 Salvia verticillata. , 

 Polygonum Virginicum. 



Fig. 460. -Catapult fruits. 



*. 6 and Teucrium Euganceum. 1 and 8 Teucriam flavum. 

 , s and 10 nat . size ; the others magnified. 



Monarda fistulosa. 10 and 



of the pappus bristle up, and in so doing raise the fruits to the open mouth of the 

 basket. If the peduncle supporting the capitulum is now set in motion, the fruits 

 are tossed out like shuttle-cocks. The bristly pappus-hairs are not in this case 

 organs of flight ; they are short and stiff, and, besides raising the fruits, serve also 

 to determine the direction of their fall. Balistic apparatus very similar to that 

 just described is also found in several Iridacece, Liliacece, Caryophyllacece, Primu- 

 lacece, and Scrophulariacece, only in them the erect, resilient stem does not bear a 

 fruit-capitulum but a capsule, and the ejected particles are not fruits but seeda 

 The seeds are comparatively large and heavy, and are destitute of membranous or 

 hairy appendages. In all these cases the capsule is situated with its orifice upwards 

 and only opens in dry weather. As its cavity is very deep, no ejection of the seeds 

 ensues except when the resilient stalk which carries it sways somewhat violently 

 to and fro. 



