Fronds.—Lance-ovate, twice-pinnate; pinnæ oblique to the rachis, elongated-triangular, the lower ones broadly triangular; pinnules oblique to the midrib, connected by a narrow wing, cut into thorny-toothed segments; fruit-dots round; indusium smooth, without marginal glands, soon withering.
To my knowledge I have only seen this fern in the herbarium, it being rare in this country. It is found, I have been told, chiefly toward the tops of mountains. Its pinnæ are noticeably ascending.
Var. intermedium (D. spinulosa intermedia)
Labrador to North Carolina, in woods almost everywhere. Usually large, with somewhat chaffy stalks, having brown, dark-centred scales.
Fronds.—Oblong-ovate, 2-3 pinnate; pinnæ oblong-lance-shaped, spreading, rather distant, the lowest unequally triangular, the pinnules on the lower side longer than those on the upper side; pinnules ovate-oblong, spreading, with oblong lobes thorny-toothed at the apex; fruit-dots round; indusium delicate, beset with tiny stalked glands.
This is the form of the species that abounds in our woods. Perhaps no one plant does more for their beauty than this stately fern, whose rich-green, outward-curving fronds spring in circles from fallen trees and decaying stumps as well as from the ground.
PLATE XXVIII
BOOTT'S SHIELD FERN
a Tip of fertile pinna
The plant varies greatly in height, breadth, and way of holding itself. Sometimes the fronds stand three feet high, and are broad and spreading. Again, they are tall, slender, and somewhat erect. Again, they are not more than a foot high.