. Introduction to botany. Botany. SEED DISTEIBUTION 169 Evidently no kind of flowering plant actually increases at any such rate as has just been suggested, or it would soon crowd most others out of existence. The means by which the unlimited multiplication of any one species is prevented are lack of ex- tremely rapid and thorough means of disseminating the seeds, multiplication of the insect and plant enemies of the species (a factor which is often not very important), and over-crowding or competition with other plants of the same or of different species. 161. Competition as a check on in- cr
. Introduction to botany. Botany. SEED DISTEIBUTION 169 Evidently no kind of flowering plant actually increases at any such rate as has just been suggested, or it would soon crowd most others out of existence. The means by which the unlimited multiplication of any one species is prevented are lack of ex- tremely rapid and thorough means of disseminating the seeds, multiplication of the insect and plant enemies of the species (a factor which is often not very important), and over-crowding or competition with other plants of the same or of different species. 161. Competition as a check on in- crease. No one can realize just what competition among plants means un- less he makes some careful out-of-door studies of plants growing under condi- tions of great overcrowding. A por- tion of a grainfield too thickly sown, a very weedy bit of garden soil left to itself for the whole growing season, or a piece of recently cleared forest in which coppice growth is starting from old stumps, or where seedling trees are springing up in great num- bers— any one of these will teach a most important lesson. The writer has found wild-black-cherry seedlings, to the number of more than 100 to the square foot, beginning to grow in the spring under a large wild-cherry tree. As the parent tree was in thrifty condition and its top was nearly 30 feet in diameter, there might have been some 70,000 seedling cherries every year killed by crowding and shade under this one tree, although, in fact, there were never so many as Fig. 150. Cockleburs This troublesome weed often grows along a path, where men carry the seeds back and forth in their clothing, and animals in their hair or fur. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Bergen, Joseph Y. (Joseph Young), 1851-1917; Caldwell, Otis William, 1869- joint author.
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