fern

Castro-Aguiar, Pedro Henrique, Fernandes, Rozijane Santos & Zappi, Daniela Cristina, 2025, Ferns of the Parque Nacional das Nascentes do Rio Parnaíba Brazilian Cerrado, Rodriguesia (e 00612024) 76, pp. 1-24 : 3-4

Key for fern genera in the PNNRP, Brazil

1. Sporangia with apical annulus found only in the basal pair of modified pinnae (fronds hemidimorphic) or located at the margin of the pinnae, in this case with the fertile frond distinct from the sterile ones (fronds holodimorphic)...............................................................................................1. Anemia ( Anemiaceae )

1’. Sporangia with longitudinal or obliquous annulus, gathered in sori beneath or marginally in the laminae

2. Fronds pseudodichotomously cleft, with hairy or scaly dormant buds between the lateral branches, generally scandent over the vegetation; sporangia normally 3–10(–15) per sorus.............................. ..................................................................................................................8. Dicranopteris ( Gleicheniaceae )

2’. Fronds simple, pinnate, or many-divided, without dormant buds, not scandent and not pseudodichotomously cleft; sporangia> 15 per sorus.

3. Arborescent plants with caudices ...........................................................4. Cyathea ( Cyatheaceae )

3’. Herbaceous or creeping plants without caudices.

4. Laminae translucent, 1–2 cell layers between the veins; sori marginal, indusium tubular ..........................................................................................9. Trichomanes ( Hymenophyllaceae )

4’. Laminae not translucent,> 2 layers of cells between the veins; sori abaxial or submarginal; indusia or pseudoindusia rounded, oblong or linear.

5. Sori protected by retroflexed laminae margins (pseudoindusium).

6. Stem long-creeping, hairs present; laminae 4-pinnate-pinnatifid, with farinaceous appearance beneath.......................5. Pteridium ( Dennstaedtiaceae )

6’. Stem short-creeping to ascendant, scales present; laminae 1- or 2-pinnate, without farinaceous appearance beneath.

7. Presence of veins in the pseudoindusium; fronds 1-pinnate, last segments flabellate, glabrous; stem with concolorous scales ................................................................................. 12. Adiantum ( Pteridaceae )

7’. Absence of veins in the pseudoindusium; fronds 1-pinnate distally to 2-pinnate proximally; last segments ovate-oblong, pubescent; stem with bicolor scales................13. Cheilanthes ( Pteridaceae )

5’. Sori not protected by retroflexed laminae margins (indusia absent or present).

8. Laminae simple; sori acrostichoid ................................................ 7. Elaphoglossum ( Dryopteridaceae )

8’. Laminae divided; sori linear, oblong or rounded.

9. Sori linear, adjacent, and parallel to the midrib.

10. Stem erect or decumbent; fronds pinnatissect or 1-pinnate; pinnae not articulated with the rachis, without scales beneath the midrib ........................... 2. Blechnum ( Blechnaceae )

10’. Stem long-creeping; fronds 1-pinnate; pinnae articulated with the rachis, with scales beneath the midrib............................................................. 3. Telmatoblechnum ( Blechnaceae )

9’. Sori circular or linear disposed along the veins, not adjacent or parallel to the midrib.

11. Pinnae with white wax abaxially; sori linear along the veins; indusia absent ................... .................................................................................................. 14. Pityrogramma ( Pteridaceae )

11’. Pinnae without white or yellow wax abaxially; sori not following the veins; indusia absent or present.

12. Fronds 1- or 2-pinnate, pinnae or pinnules dimidiate or semilunar ........................... ............................................................................................... 10. Lindsaea ( Lindsaeaceae )

12’. Fronds 1-pinnate or 1-pinnate-pinnatifid, pinnae or pinnules linear or lanceolate.

13. Sori with indusia.

14. Veins anastomosed; fronds dimorphic, 1-pinnate ........................................ ....................................................................... 6. Cyclodium ( Dryopteridaceae )

14’. Veins free; fronds monomorphic, 1-pinnate-pinnatifid ............................... ......................................................................15. Christella ( Thelypteridaceae )

13’. Sori without indusia.

15. Stem densely pubescent, with multicellular hairs; veins free; sori circular, on the costal midribs .......................................... 11. Metaxya ( Metaxyaceae )

15’. Stem glabrous; veins anastomosed; sori oblong or linear on the meniscioid veins ......................................................... 16. Meniscium ( Thelypteridaceae )