The power of growth exhibited by ostrich ferns 



George E. Stone 



The power of growth exerted by plants is frequently so great 

 that the work accomph'shed in some cases seems almost incredible. 

 It is the purpose of this paper to give the results of some obser- 

 vations made by the writer relating to the power of growth in 

 plants, 



r 



The writer has had for many years a number of ostrich ferns 

 {pnoclea Struthiopteris Hoffm.) growing about his residence, where 

 he has had an opportunity to observe them daily. " These ferns 

 have received the best oi care and many of them have attained a 

 very large size. Previous to planting them the beds in which they 



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are growing were dug out to a depth of a few feet and filled with 

 soil most suitable for their luxuriant development. Some of these 

 beds are located close to the house, which has a border of tar con- 

 crete varying from 2)4 to $ feet in width. The ferns growing 

 close to this border spread profusely and as the beds are rather 

 limited in size the ferns frequently push their rhizomes under the 

 concrete and the young frond stalks force themselves up through 

 it. The concrete is composed of tar and coarse gravel mixed and 

 rolled in the usual way, and has been laid for a number of years. 

 It is from 2^ to 3 inches thick and exceptionally hard, and a 

 heavy stroke from a sledge-hammer makes little or no impression 



upon it. 



The rupturing of the concrete by the young frond shoots 

 occurs almost yearly. Sometimes the concrete is ruptured where 

 it joins the underpinning of the house, and again the ferns come 

 up through the middle of the concrete. This occurs in the spring, 

 when growth is active and when the fronds are unfolding. While 

 those fronds which push themselves up through the concrete are 

 necessarily more backward in unfolding than those not obstructed 

 in their growth, it requires only a week or ten days, as a rule, for 

 them to rupture the concrete, after which time they unfold quite 



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