Onoclea Sensibilis, forma obtusilobata 
H. C. RIDLON 
Regarding the so-called variety or form obtusilobata 
of the sensitive ferr, there seems to be quite a difference 
of opinion as to the cause of this form, and thus I venture 
to give my own experience. 
Seven years ago I found my first obtusilobata form 
growing among perfectly formed fertile and_ sterile 
fronds of the same fern, all growing close to a roadside 
thicket which afforded partial shade, and in a location 
which throughout the year was moist. 
or five consecutive years I was able to find this 
form, then, after a lapse of two years during which the 
station was not visited, I again found the form. As 
this roadside was undisturbed by: scythe or grazing 
cattle, I am unable to account for this re-appearance 
each year. 
I have tried, without success, to produce this form 
by removing all normal fronds, also by growing in dry, 
sterile soil. 
SPRINGFIELD, Vr. 
Mr. Ridlon presents a fresh bit of evidence on a still 
unsettled question—the cause of the “obtusilobata” 
forms of the sensitive and other dimorphic ferns. His 
evidence is of the more value because he is not only a 
careful observer, but an expert in growing plants; and 
his attempt to produce these forms by means of partial. 
starvation arising from other causes than mutilatien 
of the plant is, so far as the present commentator 1s 
aware, an original experiment. 
A resumé of the evidence in regard to the cause of 
obtusilobata forms may be of interest here. In 1881 
Prof. Underwood Suggested that they were modified 
fertile fronds, and resulted from destruction of the sterile 
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