1. Dryopteris carthusiana (Vill.) H.P. Fuchs (spinulose wood fern)
Pl. 6c; Map 21
D. austriaca (Jacq.) Woyn. ex Schinz & Thell. var. spinulosa
(O.F. Müll.) Fiori
D. spinulosa (O.F. Müll.) Watt
Rhizome and petiole scales tan, concolorous, not shiny, linear to ovate. Leaves
25–95 cm long, monomorphic, herbaceous to papery. Leaf blades deltoid to
narrowly elliptic in outline, 2 times pinnately compound above to often 3 times
pinnately compound below, glabrous, flat. Pinnae 7–115 mm long, narrowly
triangular to linear, the tips attenuate, the margins toothed, the pinnules
mostly deeply lobed. Basal lower segment of basal pinnae 2 or 3 times longer
than the basal upper segment and longer than the adjacent basal segment. Sori
about halfway between the midribs and margins of the pinnules or pinnule lobes.
Indusia glabrous, shriveling at maturity. Spores 49–62 mm long. 2n=164.
Uncommon and widely scattered in eastern and central Missouri
(northern U.S. south to Washington and South Carolina,
Canada, Europe, Asia). Moist slopes in mesic forests, often on acidic
substrates, swamps, less commonly in bottoms of sinkholes and on ledges of
shaded sandstone bluffs.
This tetraploid species arose following hybridization between D. intermedia
and another unknown, diploid, possibly extinct taxon known to hopeful botanists
by the unpublished name, “D. semicristata.” D. carthusiana
greatly resembles D. intermedia, but can be separated from that species
by the absence of tiny glands on the leaf blades and by the shape of the basal
pinnae (see the key above).
The distribution of the spinulose shield fern is highly disjunct in the state
with isolated occurrences in the Bootheel counties, the Ozark Border counties
near St. Louis, the Glaciated Plains in
northeastern Missouri, and a single occurrence
in the bottom of a large sinkhole in Camden
County in the Ozarks.
Unlike D. intermedia, which grows predominantly on sandstone ledges,
most of the populations of D. carthusiana in Missouri are on the forest floor.