and its variety _intermèdium_, and with Goldie's fern; also between the
crested fern, including Clinton's variety and each of the others mentioned;
and, in fact, between almost all pairs of species of the wood ferns,
although we do not think they have been positively verified. Still other
species of ferns are known to hybridize more or less, as we saw in the case
of Scott's spleenwort.

[Illustration: Crested Marginal Fern. A Hybrid. _Aspidium Cristatum X
marginale_ (Fernery of Geo. E. Davenport)]

[Illustration: _Aspidium cristatum X marginale_ One of the very best for
cultivation]

(5) BOOTT'S SHIELD FERN

_Aspidium Boottii_. THELÝPTERIS BOOTTII

_Dryopteris Boottii. Nephrodium Boottii_

Fronds one to three feet high, oblong-lanceolate, bipinnate, the upper
pinnæ lanceolate, the lower triangular with spinulose teeth. Sori in rows
each side of the midvein, one to each tooth and often scattering on the
lower pinules. Indusium large, minutely glandular, variable.

This fern has been thought to be a hybrid between the crested and spinulose
ferns, but is now regarded as distinct. Like the crested fern its fertile
fronds wither in autumn, while its sterile blades remain green throughout
the winter. It differs from it, however, by being twice pinnate below, and
from the typical spinulose fern by its glandular indusium; but from the
intermediate variety it is more difficult to separate it, as that also has