150 THE STORY OF THE PLANTS. 



little nuts in the meadow buttercup, but many- 

 seeded pods in the marsh-marigold and the lark- 

 spur. Where the carpels have combined into a 

 single ovary, we get a many-chambered fruit, as 

 in the poppy, which consists, when cut across, of 

 ten seed-bearing chambers. Most fruits are dry 

 capsules or pods, either single, as in the pea, the 

 bean, the vetch, and the laburnum ; or double, as 

 in the wallflower and shepherd's-purse ; or many- 

 chambered, as in the lily, the wild hyacinth, the 

 poppy, the campion. As a rule the fruit consists 

 of as many carpels or as many chambers as the 

 unfertilised ovary. 



Fruits are often dispersed entire, and this is 

 especially true when they contain only one or 

 two seeds. In such instances they sometimes fall 

 on the ground direct, as is the case with most 

 nuts ; or else they have wings or parachutes which 

 enable the wind to seize them, and carry them 

 to a distance, where they can alight on unex- 

 hausted soil, far away from the roots of the 

 mother plant. Such fruits are common among 

 forest trees. The maples, for example, have a 

 double fruit, often called a key^ which the wind 

 whirls away as soon as the seeds are ready for 

 dispersion (Figs. 37, 2i^^ 39, 40, 41). In the lime, 

 the common stalk of the flowers is winged by a 

 thin leaf; and when the little nuts are ripe the 

 wind detaches them and carries them away by 

 means of this joint parachute. In the birch, elm, 

 and ash the fruit is a one-seeded nut, with its edge 

 produced into a leathery or papery wing, which 

 serves to float it. 



But more often the fruit at maturity opens 

 and scatters its seeds, as we see in the pea, the 

 wild hyacinth, and the iris. Sometimes the seeds 



