Flora of North America species comparison

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Gymnocarpium robertianum

gymnocarpe de Robert, limestone oak fern, scented oakfern
Stems

1–2 mm diam.;

scales 2–4 mm.
Fertile leaves

usually 10–52 cm.
Petiole

5–33 cm, with numerous glandular hairs distally;

scales 2–6 mm.
Blade

broadly deltate, 2–3-pinnate-pinnatifid, 5–19 cm, usually firm and robust, abaxial surface moderately to densely glandular, rachis densely glandular, adaxial surface moderately glandular.
Ultimate segments

of proximal pinnae oblong, entire to slightly crenate, apex entire, rounded.
Pinnae

of 2d pair usually stalked, if sessile then with basal basiscopic pinnule usually shorter than adjacent pinnule and equaling basal acroscopic pinnule;

basal acroscopic pinnule shorter than adjacent pinnule, apex often entire, rounded.;

pinnae of 3d pair usually sessile with basal basiscopic pinnule shorter than adjacent pinnule and equaling basal acroscopic pinnule;

basal acroscopic pinnule equaling or shorter than adjacent pinnule.
Spores

34–39 µm. 2n = 160.
Pinna

apex acute.
Proximal

pinnae 3–13 cm, ± perpendicular to rachis, basiscopic pinnules ± perpendicular to costa;

basal basiscopic pinnules either sessile or stalked, pinnate-pinnatifid or pinnatifid, if sessile then with basal basiscopic pinnulet usually shorter than adjacent pinnulet; 2d basal basiscopic pinnule sometimes stalked, if sessile then with basal basiscopic pinnulet shorter than or equaling adjacent pinnulet;

basal acroscopic pinnule sometimes stalked, if sessile then with basal basiscopic pinnulet shorter than or equaling adjacent pinnulet.

Gymnocarpium robertianum
Habitat Calcareous substrates, limestone pavement, outcrops, and cliffs, Thuja swamps
Elevation 0–1000 m (0–3300 ft)
Distribution
from FNA
IA; MI; MN; WI; MB; NB; NF; ON; QC; Europe; Asia in Caucasus Mountains
[WildflowerSearch map]
[BONAP county map]
Discussion

Gymnocarpium robertianum occurs in numerous localities in eastern Canada, especially in Ontario and Quebec where it is widely distributed; populations are small. Hybrids with G. robertianum are extremely rare. Gymnocarpium × heterosporum W. H. Wagner, a putative triploid hybrid between G. robertianum and G. appalachianum, is known only from one county in Pennsylvania (plants now extirpated, K. M. Pryer 1992). Gymnocarpium × achriosporum Sarvela, a putative tetraploid hybrid between G. robertianum and G. dryopteris, is known only from Sweden and two localities in Quebec. Both hybrids resemble G. robertianum in their leaf morphology and dense glandularity but have black, malformed spores.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 2.
Parent taxa Dryopteridaceae > Gymnocarpium
Sibling taxa
G. appalachianum, G. disjunctum, G. dryopteris, G. jessoense
Synonyms Polypodium robertianum, Dryopteris robertiana, Phegopteris robertianum, Thelypteris robertiana
Name authority (Hoffmann) Newman: Phytologist 4: app. 24. (1851)
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Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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