BOTANY OF LA SAL,L,E COUNTY . 35 



But some plants are much more prolific than this. 

 The cockle burr, Xanthium, matures more than 200 

 burrs on each medium-sized plant, and as these plants 

 do not require more than a square foot apiece there 

 may be perfected on a single acre not less than 8,700,- 

 000 of these burrs, each of which contains two seeds, 

 warranted to grow. 



We have found on a medium sized Oenothera no less 

 than 218 pods, each containing- over 100 seeds; on a 

 Polyginum from 3,000 to 3,600 seeds; on a sunflower, 

 Helianthus grosseserratus, 6,000 to 7,000 seeds, and 

 they will probably average 1,000 each, and the plants 

 often stand two or three to the square foot. 



While some plants, and the especially worthless 

 ones, are so fruitful, others are comparatively barren 

 or produce few seeds, a few producing but one flower, 

 some three to five flowers each, but these flowers are 

 generally many -seeded, and each head perfects 50 or 

 more seeds. 



It will be seen from the above facts that nature is a 

 most prodigal sower, scattering seeds with a lavish 

 but most inconsiderate zeal, the greater part of them 

 to perish at the very dawn of life, but few compara- 

 tively to reach maturity and assist in perpetuating 

 the race. 



How Plants Travel. That plants extend the 

 area over which they are found is well known and this 

 with many of them is easily accounted for, some hav- 

 ing been brought in grain that was sown or among 

 seeds that were planted in gardens. Sometimes too 

 straw has been used as material for packing goods and 

 the seeds of weeds were mingled with it. Thus, even 

 while aiming to advance his interests and promote his 

 comfort and convenience by introducing grains of the 

 best quality or testing some new crop man has brought' 



