Adderstongue: Ophioglossum vulgatum
- The identification features of this species and its photograph.
- http://www.plant-identification.co.uk/skye/ophioglossaceae/ophioglossum-vulgatum.htm

Small Adderstongue: Ophioglossum azoricum
- A description of this species with several photographs.
- http://www.plant-identification.co.uk/skye/ophioglossaceae/ophioglossum-azoricum.htm

Ophioglossum petiolatum
- Accession record from University of Connecticut.
- http://florawww.eeb.uconn.edu/acc_num/199700050.html

Ophioglossum pendulum
- Photographic image.
- http://www.botany.hawaii.edu/faculty/carr/images/oph_pen.jpg