DOGBANE FAMILY 



Dogbane, a plant common enough all summer, along 

 shady roadsides and around the borders of thickets. 

 It grows about three feet high, erect, and branching. 

 The blossoms are nearly the size and much the shape 

 of a single flower of Lily-of-the-Valley. The bell- 

 shaped corolla has five lobes that spread and curve 

 outward. The color is white, but five pink lines run 

 down from the edge of the bell to the centre. These 

 say to the visiting insect as clearly as flowers can talk: 

 "At the bottom of the cup is nectar." 



At the bottom of the cup is not only nectar but a 

 trap as well — in fact, five traps, as Miiller, who has care- 

 fully studied the plant, clearly shows. His account 

 is virtually as follows: At the base of the cup are five 

 nectar-bearing glands. These stand in a ring around 

 the pistil. Outside them is the ring of stamens, five 

 in number; in shape the anthers are like arrow-heads. 

 At the two points at the base of the arrow-head are 

 two hard little horns, and the anthers stand so close 

 together that the horn of one anther stands close to 

 the horn of another. Now, curiously enough, inside 

 the corolla, near its base, are five triangular bodies 

 with their points up and placed so that they alternate 

 with the stamens and a little below them, so that each 

 triangular body on the corolla covers two little horns 

 of the stamens by a sort of interlocking. The result 

 is that a weak insect coming for nectar, and putting its 

 proboscis in between the anthers as it must to get the 

 nectar, finds itself caught by the three interlocking 

 points as in a trap. If strong, it pulls itself free; if 

 weak, it is held and dies of starvation. The puzzle 

 is: In what way is the plant benefited, and if not 

 benefited why does it do it? 



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