FRUITS AND SEEDS. 259 



and the Goafs-beard, where the pappus forms a parachute 

 carried on a stalk. If the air becomes moist the parachute 

 closes up, and the fruit falls to the earth, and is washed into 

 the soil by the first shower of rain. 



Dispersal by wind involves a greater loss of seeds than 

 dispersal by animals, for the latter usually frequent fertile 

 localities where the seeds have a chance of germinating, 

 whereas wind-dispersed seeds may fall upon sterile or un- 

 suitable localities, or may be carried out to sea. It is for 

 this reason that winged and hairy seeds are usually absent 

 from the plants of the seashore. Hence also arises the fact 

 that wind-dispersed seeds are usually produced in relatively 

 greater abundance than those dispersed by animals. 



Examine and sketch, with special reference to their adaptations for 

 wind-dispersal, the fruits of Poppy, Canterbury Bell, Campion, Stitch- 

 wort, Cow Parsnip, Buttercup, Ash, Elm, Birch, Maple, Sycamore, 

 Hornbeam, Hop, Lime-tree, Marvel of Peru, Docks, Thrift, Clematis, 

 Cotton-Sedge ("cotton-grass," in bogs), Valerian, Dandelion, Goafs- 

 beard, Thistle, Groundsel ; and the seeds of Willow, Poplar, Willow- 

 herb, Pine, Yellow Rattle, Bignonia. 



289. Dispersal by Water is uncommon, and occurs chiefly 

 in aquatic plants. Seeds may also be carried on the mud 

 adhering to the feet of aquatic birds. In plants which grow 

 on the margin of streams, as well as in those aquatics whose 

 leaves are aerial (e.g. Water Plantain, Arrow-head), the seeds 

 may fall into the water. In some casts (e.g. Alder) the seeds 

 are enabled to float to a distance by being provided with a 

 spongy covering which contains air. This is also the case in 

 Water Lilies, but in these and in most submerged or float- 

 ing water-plants the fruits are developed under water, and 

 are either achenes, nuts, or splitting fruits which separate 

 into hard one-seeded parts. 



290. Dispersal by Animals may be either passive or 

 active, and the seeds may be carried either inside or outside of 

 the animal's body. Animals assist in seed-dispersal in three 

 ways. (1) Some plants have fruits bearing hooks, which 

 catch on to the fur of animals and are then carried off. 

 (2) Juicy fruits are eaten by animals, chiefly birds, the seeds 

 being protected by a hard shell which can pass uninjured 

 through the alimentary canal. (3) In the third method, 



