Adiantum species

Kuo, Li-Yaung, Hsu, Tian-Chuan, Chang, Yi-Han, Huang, Yao-Moan & Chiou, Wen-Liang, 2016, Systematics of the Adiantum philippense complex (Pteridaceae, Polypodiales) in Taiwan, Phytotaxa 263 (2), pp. 113-121 : 119

Key to the once-pinnate Adiantum species in Taiwan

1. Stipes, rachis and stalks winged ................................................................................................................................... A. soboliferum

- Stipes, rachis and stalks terete............................................................................................................................................................2

2. Rachis densely hirsute adaxially, sparse to densely hairy abaxially; laminae glabrous to densely hirsute........................................3

- Rachis glabrous adaxially, glabrous to very sparsely hairy abaxially; laminae glabrous...................................................................4

3. Basal pinnae semiorbicular; stalks 1–3 mm ................................................................................................................. A. malesianum

- Basal pinnae flabellate; stalks 0.5–1 mm ........................................................................................................................ A. caudatum

4. Stalks of basal pinnae less than 3 mm long........................................................................................................................................5

- Stalks of basal pinnae 3–25 mm long.................................................................................................................................................6

5. Pinnae opposite or subopposite; stalks 1–3 mm long; pinnules nearly orbicular.................................................. A. capillus-junonis

- Pinnae alternate or only basalmost pair subopposite; stalks less than 1 mm long; pinnules semidimidiate................ A. edgeworthii

6. Rachis sparsely hairy abaxially; basal pinnae semiorbicuar ................................................................................. A. × meishanianum

- Rachis glabrous; basal pinnae flabellate.............................................................................................................................................7

7. Spores 64 per sporangia; sterile pinnules with upper margin lobed for 1/3–2/3 of length; fertile pinnules with upper margin lobed for 1/3–1/2 of length; false indusia 2–6 mm wide..................................................................................................... A. menglianense

- Spores 32 per sporangia; sterile pinnules with upper margin crenate or lobed for less than 1/3 of length; fertile pinnules with upper margin subentire, undulate or lobed for 1/3(–1/2) length; false indusia 2–12 mm wide ............... A. philippense subsp. philippense