40. SPINULOSE WOOD FERN
Aspidium spinulosum (Dryopteris spinulosa)
Newfoundland to Kentucky. The common European type, rare in North America. One to two and a half feet high, with stalks having a few pale-brown deciduous scales.
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.
At its best it grows with almost tropical luxuriance and is a plant of rare beauty, its fronds having a certain featheriness of aspect uncommon in the Aspidiums.
Var. dilatatum (D. spinulosa dilatata)
Newfoundland to North Carolina, chiefly in the mountains.
Fronds.—Usually large, broader at base than in either of the preceding species, ovate or triangular-ovate, oftenest thrice-pinnate; pinnules lance-oblong, the lowest often much elongated; fruit-dots round; indusium smooth.
This form of the Spinulose Wood Fern is distinguished chiefly by its broader fronds and by the smooth indusia. As these indusia can be seen satisfactorily only by the aid of a magnifying-glass, there is frequently some difficulty in distinguishing this variety. Occasionally it occurs in a dwarf state, fruiting when only a few inches high.