BULLETIN 



OF THE 



TORREY BOTANICAL CLUB 



Vol- VIII-1 New York, October, 1881. [No. 10. 



I02. Onoclea sensibilis, var. obtusilobata. 



By Geo. E. Davenport. 



The notes on the variations in Onoclea by Prof. Underwood in the 

 September number of the Bulletin lead me to contribute some of 

 my own observations toward supplying data for an explanation of the 

 causes by which the obtusilobata form is produced. 



I have collected this interesting form of the Onoclea so many tim^s, 

 under conditions that utterly precluded all possibility of the speci- 

 mens being the result of interference with the free growth of the 

 plants which bore them, that I have long been inclined" to regard it 

 as an outcome of some inherent tendency on the part of the nor- 

 mal (?) form of the species to break up into other forms, or as a pos- 

 sible reversion to an older type, 



I have collected specimens late in the season, in open meadow 

 lands, where its appearance subsequent to mowing time suggested a 

 probable cause and effect, but, as I also collected it plentifully in sit- 

 uations w^here no scythe ever ventured, and where the plants were 

 not only as well protected from accident as it is possible for plants in 

 nature to be, but were otherwise perfectly developed — the sterile 

 fronds being well grown — and in some cases bearing normally-de- 

 veloped fertile fronds as well as the variation, I was led to believe 

 that the plants in the meadows might still have produced obtusilobata 

 forms even if they had not been interfered with by the mowers. 



I was further confirmed in this view by finding one season, near 

 a rivulet, and on a stony patch left tmmotan at the edge of a meadow 

 newly mown, some of the finest specimens of obtusilobata that I have 

 ever collected. From one plant I obtained four specimens of obtusi- 

 lobata. 



This plant I marked, and, re-visiting it the following season, found 

 that it had resumed its normal habit and produced fertile fronds of 

 a normal character ; yet there had not been any change whatever in the 

 conditions by which the plant was surrounded. Now what caused this 

 plant to deviate from its normal habit one season and return to it 

 another under conditions apparently similar — so far as any ordinary 

 observation could judge — in both seasons, and when there was no 

 perceptible outside disturbance to interrupt or interfere in any way 

 with its free growth ? . 



I collected one season sixty specimens of obtusilobata^ in^yarious 

 stages of development, io one locality from plants, some of which had 

 been injured in various ways and some of which were well supplied 

 with healthy sterile fronds ; but the next season I was unable to find 

 a single specimen of the variation there, although I searched care- 

 fully, and found plenty of plants injured as before, the locality being 

 one that was exposed to all sorts of accidents. 



During the seasons of 1873-74 I niade a series of experiments for 



