

Minnesota Plant Life. 183 



parts of the same plant that produced the large-spore. The 

 meat of the seed, or albumen, belongs to the female, for it is 

 produced within the large-spore as it germinates. The embryo 

 plantlet of the seed belongs to the new spore-producing genera- 

 tion and arises by the segmentation of an egg. After it has 

 renewed its development when the seed has germinated and 

 the plantlet has become old enough it will be able in its turn 

 to produce spores. Therefore, the life-history of a cottonwood, 

 for illustration, is twice as complex as that of a man. While 

 there are only two kinds of individuals in the human species, 

 there are four in the cottonwood: first, the pollen-producing 

 tree or staminate cottonwood; second, the seed-rudiment-pro- 

 ducing tree or pistillate cottonwood; third, the male cotton- 

 wood or pollen-tube arising from the pollen-spore and growing 

 as a parasite upon the tissues of the young cottonwood fruit; 

 fourth, the female cottonwood, a microscopic plant inclosed in 

 her spore deep within the rudimentary seed. Indeed there may 

 even be five kinds of cottonwoods, for in higher seed-producing 

 plants there is strong reason to suppose that the albumen of the 

 seed is in reality a degenerate plantlet a twin brother of the 

 embryo produced from an egg, rather than, as in the pines, a 

 portion of the female plant-body. 



From this discussion it will be seen how inaccurate is the 

 common statement that higher plants grow from seeds while 

 lower plants are produced by spores and it is understood how 

 erroneous is the phrase, so general, especially in popular works, 

 that the spores are the seeds of the fungi or ferns. The higher 

 plants produce spores just as truly as do the lower plants, 

 but in the former a peculiar relation of dependence has come 

 to exist, precisely the reverse of that which was observed in the 

 liverworts. In the latter the capsular plants, that is, the spore- 

 producing plants, were dependent upon the sexual plants for 

 their food-supply and remained perched upon their bodies all 

 through life. In the club-moss group these little perched plants 

 learned how to maintain an entirely independent existence and 

 put forth leaves and roots of their own. In the seed-plants they 

 have become so important and powerful that they do all the 

 vegetative work of their species while the once stronger and 

 larger sexual plants are reduced to microscopic structures of 



