Found occasionally throughout New England and New Jersey. Other supposed hybrids have been found between the marginal shield and the spinulose fern 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 indusiate glands. The collector needs to study authentic specimens and have in mind the type, with its rather long, narrow blade as an aid to the verbal description, and even then he will often find it an interesting puzzle. Shaded swamps throughout our area.