ADIANTUM Group

1Water plants; sporangia borne singly and protected by reflexed edges of the lamina.
1'Land plants; sporangia in sori or more or less acrostichoid.
2Rigid hairs or bristles on rhizome and bases of stipes.
2'Scales on rhizome and bases of stipes.
3Fronds bipinnate, leaflets more or less lobed
3'Fronds simple or simply pinnate, or palmate with entire leaflets.
4Veins anastomosing only near edge of lamina; fronds simple or palmate; paraphyses (if present) with distinctive apikal cell
4'Veins anastomosing throughout lamina; fronds pinnate, trilobed or simple; paraphyses always abundant, hair-like, of many cells, apical one not different from the rest.
5Sori broad, elongate, parallel to costa and edge, or more or less spreading along the veins.
5'Sori in submarginal grooves, edges of grooves of equal thickness (Schizoloma sensu Copel.).
6Lower surface of fronds covered with white or yellow powder.
6'Lower surface of fronds not covered with such powder.
7Sori along whole length of veins on lower surface
7'Sori at ends of veins, protected by reflexed lobes of margin
8Sori elongate (continuous or broken) along margins of lamina and protected by reflexed margin.
8'Sori otherwise.
9Fronds much dissected, the ultimate lamina-lobes small and connected by a narrow wing.
9'Fronds, if much branched, having quite distinct leaflets not joined by a wing.
10Fertile lobes much broader than sterile, the whole of each margin bearing a broad thin reflexed indusium
10'Fertile lobes not much broader than sterile, reflexed margin not continuous along larger fertile lobes nor very broad
11Fronds simple and lobed, or deeply pinnatifid; sori quite continuous along edge
11'Fronds branched with distinct stalked leaflets
12Sori elongate along all or most of the veins.
12'Sori otherwise.
13Fronds simple
13'Fronds pinnate or bipinnate
14Sori on lower surface, spreading a little along the veins
14'Sori at ends of veins.
15Sori on surface of reflexed marginal flaps
15'Sori at ends of veins, sometimes more or less protected by reflexed marginal flaps