1. SENSITIVE FERN
Onoclea sensibilis
Newfoundland to Florida, in wet meadows.
Sterile fronds.—One or two inches to three feet high, broadly triangular, deeply cut into somewhat oblong, wavy-toothed divisions, the lower ones almost reaching the midrib, the upper ones less deeply cut; stalk long.
Fertile fronds.—Quite unlike the sterile fronds and shorter, erect, rigid, contracted; pinnules rolled up into dark-green, berry-like bodies which hold the spore-cases; appearing in June or July.
This is one of our commonest ferns, growing in masses along the roadside and in wet meadows. Perfectly formed sterile fronds are found of the tiniest dimensions. Again the plant holds its own among the largest and most effective ferns. From its creeping rootstock rise the scattered fronds which at times wear very light and delicate shades of green. There is nothing, however, specially fragile in the plant's appearance, and one is struck by the inappropriateness of its title. It is probable that this arose from its sensitiveness to early frosts.
Sensitive Fern
Though one hesitates to differ from Dr. Eaton, who described the fertile fronds as "nearly black in color" and said that they were "not very common," and that a young botanist might "search in vain for them for a long time," my own experience has been that the fresh ones are very evidently green and neither scarce nor specially inconspicuous.
I have found these fertile fronds apparently full-grown in June, though usually they are assigned to a much later date. They remain standing, brown and dry, long after they have sown their spores, side by side with the fresh fronds of the following summer.
Detail a in [Plate I] represents the so-called var. obtusilobata. This is a form midway between the fruiting and the non-fruiting fronds. It may be looked for in situations where the fern has suffered some injury or deprivation.
PLATE I
SENSITIVE FERN
a. Var. obtusilobata