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1 Main stems erect, the plants to 5 dm tall, or climbing and to 10 m long; stems noticeably differentiated in thickness from the main stem (base of plant) to the terminal branches; rhizophores 1-3 mm in diameter.
2 Stems erect to 5 dm tall; stems with dense, stiff hairs; median leaves long-acuminate to bristle-tipped
1 Main stems creeping or ascending; stems only slightly it at all differentiated in thickness from base to apex of plant; rhizophores 0.02-0.4 mm in diameter.
3 Margins of lateral leaves entire; lateral branches of the stems further branching 2-3 times
5 Leaves with margins undifferentiated or with 1-2 rows of slightly paler cells; stomates distributed over entire leaf surface
6 Megaspores 0.29-0.35 (-0.38) mm in diameter, dull, closely reticulated; apices of median leaves acute to attenuated, usually keeled but with vein not extending almost to tip; lateral leaves 1.4-2.2 mm × 0.8-1.3 mm
6 Megaspores 0.33-0.40 mm in diameter, shiny, more loosely reticulated; apices of median leaves long-attenuate to bristled, veined, the apices frequently recurved; lateral leaves ca. 1-2 mm × 0.5-1.3 mm
2 Leaves with margins undifferentiated or with 1-2 rows of slightly paler cells; stomates distributed over entire leaf surface
3 Megaspores 0.29-0.35 (-0.38) mm in diameter, dull, closely reticulated; apices of median leaves acute to attenuated, usually keeled but with vein not extending almost to tip; lateral leaves 1.4-2.2 mm × 0.8-1.3 mm
3 Megaspores 0.33-0.40 mm in diameter, shiny, more loosely reticulated; apices of median leaves long-attenuate to bristled, veined, the apices frequently recurved; lateral leaves ca. 1-2 mm × 0.5-1.3 mm