Gymnocarpium robertianum has small (10-50cm), deltate, two- to three-pinnate fronds. Fronds arise from creeping rhizomes and have long, delicate rachis. The sori are borne in round clumps on the underside of the blade and lack an indusium. This species differs from the closely related G. dryopteris in having a densely glandular rachis as well as a more sparsely glandular underside to the blade.
Gymnocarpium robertianum is thought to hybridise with G . appalachianum giving rise to Gymnocarpium × heterosporum W. H. Wagner. This hybrid was only known from Pennsylvania where it has now been eradicated. The hybrid between G. robertianum and G. dryopteris is Gymnocarpium × achriosporum Sarvela this taxon is known from Sweden and Quebec.
This species is a calcicole and as such is restricted to alkaline rich areas. In the British Isles its preferential habitat is grykes in limestone pavement. In Michigan the species is most frequent in Thuja occidentalis swamps.
- "BSBI List 2007". Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-02-25. Retrieved 2014-10-17.
- "Gymnocarpium robertianum". Natural Resources Conservation Service PLANTS Database. USDA. Retrieved 19 January 2016.
- Stace, Clive (1997). New Flora of The British Isles, second edition. Cambridge: Cambridge University Press
- Gymnocarpium robertianum at Flora of North America
- Gymnocarpium robertianum at PLANTS profile
-  List of protected plants at National Botanic Gardens of Ireland
-  Abstract on Gymnocarpium robertianum in Michigan
- Gymnocarpium robertianum at Flora of North America 
- Distribution of Gymnocarpium robertianum in the British Isles at BSBI maps 
- Gymnocarpium robertianum at Hardy Fern Library 
|This fern-related article is a stub. You can help Wikipedia by expanding it.|