Native. Perennial. Propagates by spores and by rootstocks. Season of leaf-production: April till first autumn frost. Fruiting fronds: Appear in June and July, but do not release spores until the following spring.
Ferns are usually associated with woodlands and thickets, and, though this one may be found in such places, it is equally well suited when growing in open ground, provided the soil is not dry. The plant frequents the society of the Field Horsetail and has a bad name with horsemen and sheep-keepers because of such company. But those who have carefully investigated the matter say that the fern is not poisonous, the less noticeable Horsetail being responsible for the mischief generally attributed to it. (Fig. 2).
The plant springs from a creeping rootstock which is about a third of an inch in thickness and grows not far below the surface, branching often and producing new fronds all summer until checked by frost, to which it is very sensitive. It is a rather coarse-looking plant, six inches to three feet high, the whole frond nearly triangular in outline but divided into oblong, lance-shaped, coarsely scalloped segments at the end of a long stipe, or stalk. The leaf is light green and withers quickly when plucked. The fruiting fronds are much shorter than the sterile ones; they are twice pinnate, but the segments, or pinnules, are at first so tightly rolled as to completely hide the sporangia and look like rows of green berries attached to the midrib; later they turn from green to brown, and remain stiffly standing all winter, after the green sterile fronds are withered and gone. Indeed, the fruiting fronds of two or three successive seasons may sometimes be found on one plant; but broken and empty, for the spores are cast and germinate in the spring.
Fig. 2. - Sensitive Fern (Onoclea sensibilis). X 1/5.
Drainage of the ground. The presence of the weed is indicative of unwholesome soil conditions. After drainage, one or two seasons of thorough cultivation will destroy the rather shallow-growing rootstocks and cause the plant to disappear. Distribution of the spores may be prevented by cutting the fronds in the first season, when they are immature.