DISPERSAL OF SEEDS AND FRUITS 211 



4. Cell division resulting in the elongation of the plumule 

 and the formation of the radicle. 



5. Rupturing of the seed coats. 



6. Emergence of plumule and radicle from seed. 



7. Elevation of the cotyledons and the development of 

 the primary root. 



8. Formation of chlorophyll. 



9. Growth into the seedling. 



The Seedling. The seedling is formed as a result of the 

 germination of the embryo. The embryo becomes a seedling 

 when a true stem, leaves and roots have been formed and 

 when all the reserve food has been used. The seedling then, 

 because of its roots, stem, and leaves with chlorophyll, manu- 

 factures its own food and leads an independent existence. 



DISPERSAL OF SEEDS AND FRUITS 



It appears to be an established fact that plants distribute 

 their seeds as far as possible, with the result that certain 

 species of plants often cover large areas. A single pine tree 

 will, under favorable conditions, form a pine forest from its 

 offspring. Very frequently the forest can be seen in the 

 making. Plants distribute their seeds by the wind, by water, 

 by mechanical force, by animals and by birds. 



Wind-carried. Fruits like the winged fruits or samaras 

 are easily carried about by air-currents. The seeds of the 

 milkweed, and apocynum are blown about by means of an 

 innumerable number of air-filled buoyant hairs. 



Water-carried. The seeds and fruits of many plants grow- 

 ing along streams are carried, frequently for long distances, 

 by the water. 



Mechanically Distributed. The walls of the pod of witch 

 hazel will, when dry, contract at the base and eject the 



