Key to the genera of Dennstaedtiaceae

1. Sorus supplied by a single vein, marginal or abaxial……2

1. Sorus supplied by two or more veins, marginal…………8

2. Rhizome short-creeping or ascending, dictyostelic; petiole with two vascular bundles; sori exindusiate ....... .................................................... Monachosorum

2. Rhizome long-creeping, solenostelic; petiole with one vascular bundle; sori indusiate or exindusiate ............ 3

3. Abaxial indusium absent or minute and vestigial; spores monolete............................................................ 4

3. Abaxial indusium present; spores trilete ................... 5

4. Fiddlehead of developing leaf apex protected by reduced basal pinnules; axes armed, the spines curved, apically black when mature .......................................... Hiya

4. Fiddlehead of developing leaf apex not protected by reduced basal pinnules; axes armed or not, when present, the spines straight, green to stramineous ........ Hypolepis

5. Sori abaxial, submarginal (rarely marginal); indusia usually scarious; perispore morphology comprising of rodlets that are evenly distributed or forming a network…… Microlepia

5. Sori marginal; lower indusia similar in texture to the upper indusia; perispore morphology various, never rodlets .... 6

6. Epipetiolar buds absent; adaxial axes (rachis-costae) with raised wing, the wings decurrent onto the next order; petiole bases subterete, not clearly sulcate……… Mucura

6. Epipetiolar buds usually present; adaxial axes (rachis-costae) without raised wings; petiole adaxially sulcate, the groove confluent between orders ........................ 7

7. Rhizome branched regularly, ca. 0.5 cm diam.; leaves less than 1 m long, lacking leaf buds; glabrous or pubescent, hairs catenate, spreading, the apex often with a capitate terminal cell; plants with a north-temperate distribution...................................................... Sitobolium

7. Rhizome usually unbranched, thick, ca. 0.5 to 4 cm diam.; leaves often 1–2 m long, sometimes up to ca. 12 m, often with proliferous buds, hairs various, but lacking capitate terminal cells; plants primarily tropical in distribution.................................................... Dennstaedtia

8. Veins anastomosing; pinnae opposite or subopposite....9

8. Veins free; pinnae all or mostly alternate ................ 10

9. Laminae glabrous or somewhat scaly, often glaucous; rhizomes scaly; unfurling leaf protected by reduced basal pinnules............................................... Histiopteris

9. Laminae pubescent, green, not glaucous; rhizomes pubescent; unfurling leaf not protected by reduced basal pinnules................................................... Blotiella

10. Rachises flexuous; spores monolete .................. Paesia

10. Rachises straight; spores trilete ................... Pteridium