Gymnocarpium jessoense subsp. parvulum
Gymnocarpium
Asian oakfern, gymnocarpe du japon sous-espèce fréle, Nahanni oak fern
oak-fern
0.5–1.5 mm diam.;
scales 1–4 mm.
long-creeping, stolons absent.
monomorphic, dying back in winter.
usually 8–39 cm.
5–25 cm, with moderately abundant glandular hairs distally;
scales 2–6 mm.
ca. 1.5–3 times length of blade, base not swollen;
vascular bundles 2, lateral, ± oblong in cross section.
narrowly deltate to narrowly ovate, 2-pinnate-pinnatifid, 3–14 cm, firm and robust or lax and delicate, abaxial surface moderately glandular, rachis moderately to densely glandular, adaxial surface glabrous.
broadly deltate, ternate, or ovate, 2–3-pinnate-pinnatifid, reduced distally to pinnatifid apex, herbaceous.
of proximal pinnae oblong, entire to slightly crenate, apex entire, rounded.
of 2d pair almost always sessile with basal basiscopic pinnule usually equaling or slightly shorter than adjacent pinnule and equaling basal acroscopic pinnule;
basal acroscopic pinnule equaling or slightly shorter than adjacent pinnule, apex often entire, rounded.;
pinnae of 3d pair sessile with basal basiscopic pinnule equaling adjacent pinnule and equaling basal acroscopic pinnule;
basal acroscopic pinnule equaling or slightly shorter than adjacent pinnule.
weakly articulate to rachis but persistent, segment margins entire to crenate;
proximal pinnae longest, petiolulate, usually ± inequilateral with pinnules on basiscopic side longer than those on acroscopic side;
costae adaxially grooved, grooves not continuous from rachis to costae;
indument lacking or of minute (0.1 mm) glands abaxially and sometimes along costae adaxially.
free, simple or forked.
in 1 row between midrib and margin, ± round;
indusia absent.
32–37 µm. 2n = 160.
brownish, rugose.
apex acute.
pinnae 2–9 cm, strongly curved toward apex of leaf, basiscopic pinnules strongly curved toward apex of pinna;
basal basiscopic pinnule usually sessile, pinnatifid or rarely pinnate-pinnatifid, if sessile then with basal basiscopic pinnulet often equaling adjacent pinnulet; 2d basal basiscopic pinnule sessile, with basal basiscopic pinnulet equaling adjacent pinnulet;
basal acroscopic pinnule sessile with basal basiscopic pinnulet longer than or equaling adjacent pinnulet.
= 40.
Gymnocarpium jessoense subsp. parvulum
Gymnocarpium
Hybrids between Gymnocarpium jessoense subsp. parvulum and G. dryopteris (G. × intermedium Sarvela) are usually found wherever these two taxa occur together (Finland; Manitoba, Northwest Territories, Ontario, Quebec, Saskatchewan, Yukon; Alaska, Michigan, Minnesota, Wisconsin), and they are particularly abundant in the Great Lakes region. These hybrids have sometimes been referred to as G. × heterosporum, a name that is, however, correctly restricted to unique hybrids between G. robertianum and G. appalachianum (see discussion under G. robertianum; K. M. Pryer 1992). Gymnocarpium × intermedium is intermediate between the two parental species in its leaf morphology and glandularity, and it can be readily distinguished by its small, blackish, malformed, abortive spores, as well as large, brown, round spores that may allow this taxon to reproduce apogamously. Of the Gymnocarpium sterile hybrids, G. × intermedium is the easiest to distinguish morphologically.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Species 8 (5 in the flora).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Adaxial blade surface glabrous or moderately glandular, abaxial blade surface and rachis moderately or densely glandular. | → 2 |
1. Adaxial and abaxial blade surfaces and rachis essentially glabrous. | → 3 |
2. Blades glabrous on adaxial surface; proximal pinnae and basiscopic pinnules of proximal pinnae curving toward apex of leaf and apex of pinna, respectively; pinnae of 2d pair almost always sessile with basal pinnules ± equal in length to adjacent pinnules. | jessoense subsp. parvulum |
2. Blades moderately glandular on adaxial surface; proximal pinnae and basiscopic pinnules of proximal pinnae ± perpendicular to rachis and costa, respectively; pinnae of 2d pair usually stalked, or if sessile with basal pinnules shorter than adjacent pinnules. | G. robertianum |
3. Pinnae of 2d pair and basal basiscopic pinnule of proximal pinnae stalked. | G. appalachianum |
3. Pinnae of 2d pair sessile or rarely stalked; proximal basiscopic pinnule of basal pinnae sessile. | → 4 |
4. Pinnae of 2d pair sessile with basal pinnules unequal in length (basiscopic markedly longer); ultimate segments of proximal pinnae slightly lobed to crenate, apex often crenulate, acute; blades 8-24 cm. | G. disjunctum |
4. Pinnae of 2d pair rarely stalked, if sessile with basal pinnules ± equal in length (basiscopic = acroscopic); ultimate segments of proximal pinnae crenate to entire, apex entire, rounded; blades 3-14 cm. | → 5 |
5. Sessile basal basiscopic pinnule of proximal pinnae with basal basiscopic pinnulet (division of pinnule) ± equal in length to adjacent pinnulet; pinnae of 2d pair usually sessile, with basal pinnules ± equal in length to adjacent basal pinnule; spores 34-39 µm. | G. dryopteris |
5. Sessile basal basiscopic pinnule of proximal pinnae with basal basiscopic pinnulet shorter than adjacent pinnulet; pinnae of 2d pair sessile, with basal pinnules shorter than adjacent pinnule, or 2d basal pinnae rarely stalked; spores 27-31 µm. | G. appalachianum |
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