Dicksonia, IN, IN

KEY TO THE SPECIES Of DICKSONIA View in CoL IN THE NEOTROPICS

Ambiguous yet potentially helpful characters are given in parentheses at the end of each couplet.

1. Petioles of fertile fronds relatively long, (20–) 45–90 cm, 1/4–1/2 of frond length, petioles and rachises densely covered with spreading dark reddish brown hairs with flexuous to soft tips but indurated bases, leaving a strongly scabrous epidermis from petiole to costules, not transient with softer woolly undercoat, undercoat thin, persistent; spreading red hairs present on midveins (paler spreading hairs on and between veins abaxially, numerous and persistent). [N Colombia, Venezuela?]....................................................................... Dicksonia lehnertiana View in CoL

1. Petioles of fertile fronds relatively short, 5–25 cm long, less than 1/10 of frond length (in juvenile plants to 1/2 of frond length), petioles and rachises at least in unfurling fronds covered with softer hairs, outer darker layer ± transient with softer woolly undercoat, the latter may be thick in young fronds and completely missing in older fronds, epidermis smooth to weakly, rarely strongly scabrous; spreading hairs on midveins either absent or pale (hairs on and between lateral veins either scarce to absent or abundant and persistent)....................................................... 2

2. Fronds bipinnate-pinnatifid, pinnules all ± linear with rounded segments, each only fitting one sorus acroscopically; hairs on and between lateral veins common (adventitious buds absent, segment margins strongly revolute in fresh material). [N Colombia, N Peru].......... D. stuebelii View in CoL

2. Fronds to tripinnate-pinnatifid, pinnules mostly lanceolate, larger ones distinctly triangular, segments oblong with acute to obtuse tips, each potentially with several sori acroscopically and basiscopically; hairs on lateral veins rare, never between them (adventitious buds may occur; segment margins ± planar to weakly revolute, strongly revolute margins artifact of dried specimens).................................. 3

3. Pinnae to 35 X 12 cm, frond axes abaxially glabrescent, surface smooth, most adnate fertile segments basally constricted, sinuses between them notably triangular and usually becoming wider towards the pinnule base, sori 0.9–1.2 mm diam (adventitious buds absent; larger segments 3.5–7.0 X 2.3–3.2 mm, distance receptacle/sorus base to midvein 0.6–1.2 mm). [SE Brazil, adjacent Argentina, Paraguay, Uruguay].................................................................................................................. D. sellowiana View in CoL

3. Pinnae to 77 X 29 cm, frond axes abaxially with matted or spreading hairs, the latter may leave a scabrous surface, most adnate fertile segments basiscopically decurrent, sinuses between the segments acute or rounded, not becoming wider towards the pinnule base; sori 0.9–2.0 mm diam. [Mesoamerica, Andes].................................................................................................. 3

4. Outer darker petiole hairs tangled and matted, thin-walled, partially collapsed ( Mexico to Costa Rica) to wholly catenate ( Panama to Ecuador); petiole bases with adventitious buds instead of the basal 1–2 pinna pairs (only Panama to Ecuador), producing small plants on the trunks when fronds are rotting (buds often shriveled and hidden among hairs in dried specimens); sori 1.0–1.2(–1.5) mm diam, usually not touching each other and leaving the midveins visible (larger segments 8.0–14.0 X 3.0– 4.5 mm, distance receptacle/sorus base to midvein 1.5–2.2 mm) [Mesoamerica, Chocó Region of Colombia, Ecuador]............................................... D. navarrensis View in CoL

4. Outer darker petiole hairs spreading, turgid, only in specimens appearing plastered (then hairs still straight in most parts, appearing bundled); petiole bases never with adventitious buds (lateral shoots may come directly from the trunk after injury); sori (1.2–)1.5–2.0 mm diam, mature ones often covering segments abaxially, usually touching each other and often hiding the midveins (larger segments 5.0–11.0 X 2.0–4.0 mm, distance receptacle/sorus base to midvein 0.7–1.5 mm) [Andes, higher elevations of Costa Rica,and coastal ranges of Venezuela]............................................................................................. D. karsteniana View in CoL