Flora of North America species comparison

creeping, stolons absent.

strongly dimorphic, fertile leaves usually shorter, greatly contracted, persistent 2–3 years, sterile leaves dying back in winter.

irregularly spaced along stem.

yellow-green, deltate, coarsely divided, 13–34 × 15–30 cm.

of sterile leaf ca. 1–1.5 times length of blade, petiole of fertile leaf 2–6 times length of blade, bases swollen and persisting as trophopods over winter;

vascular bundles 2, lateral, lunate in cross section.

of sterile leaf black, 22–58 cm, flattened at base;

rachis winged, becoming broader toward apex.;

petiole 19–40 cm, base sparsely scaly.

of sterile leaf deltate, pinnatifid to pinnate-pinnatifid proximally, reduced and shallowly pinnatifid distally, herbaceous to papery, blade of fertile leaf linear-oblong, 2-pinnate, leathery.

not articulate to rachis, segment margins of sterile blades entire to sinuate or shallowly lobed, margins of fertile pinnules strongly revolute and forming hardened beadlike structures;

proximal pinnae largest or nearly so, sessile or adnate, equilateral;

costae adaxially flat;

indument on both sides of linear to lanceolate scales and/or multicellular hairs on rachis and costae.

5–11 per side, lanceolate;

proximal pinnae 9–18 cm, margins entire, sinuate, or laciniate.;

pinnae linear, 5–11 per side, 2.5–5 cm; ultimate segments revolute to form beadlike structures, 2–4 mm diam.

reticulate with areoles lacking included veinlets in sterile leaves, veins free in fertile leaves.

covered by strongly revolute margins of pinnae, ± round;

indusia vestigial, triangular, persistent but not easily seen in mature leaves.

borne on free veins, enclosed by ultimate segments.

greenish, with a few low folds and numerous, minute, echinate-cristate elements.

leaves green, becoming black at maturity, oblong, 7–17 × 1–4 cm.

= 37.

= 74.