Dicksonia

Lehnert, M. & Coritico, F. P., 2018, The genus Dicksonia (Dicksoniaceae - Cyatheales) in western Malesia, Blumea 63 (1), pp. 268-278 : 278

OF DICKSONIA

1. Spreading thick bristly hairs abundant and evenly distributed on rachis and most parts of the petiole; hairs brittle, in specimens often only black indurated bases sticking out of the contrasting yellowish to pale brown undercoat of matted, flexuous to tortuous hairs (apparently translucent when wet); either outer or inner indusial valve with darkened margin, contrasting with paler remainder of the valve............... 2

1. Spreading thick hairs either not bristly or confined to petiole, if broken-off then bases inconspicuous within undercoat; indusial valves rather pale, stramineous to medium brown, if outer valve darkened then margin paler than the remainder ofit ... ... .. ... ... ... ... ... ... ... ... ... ... .. .. 4

2. Paler undercoat comparatively thin for the complete length of the petiole, at least abaxially (adaxially woolly hairs from the trunk may be adhering); bristly hairs mostly irritating, ending in a ± straight tip; hairs on costules notably denser than on veins, mainly white, antrorsely curved, with few longer, red and ± straight hairs protruding. — Philippines, Borneo........................................ 5. D. mollis

2. Paler undercoat denser towards petiole base, abaxially becoming a thick golden woolly layer with bristly hairs protruding; bristly hairs not irritating, most ending in a flexuous tip; hairs gradually thinning from costae to midveins, on costules hairs mostly spreading, longer ones reddish, shorter ones white. — Sumatra, Java, Bali, Sulawesi ............. 3

3. Outer indusial valve usually with dark brown margin; spores with evenly deposited perispore layer, appearing smooth at low magnification. — Sumatra, Java, Bali ... 2. D. blumei

3. Outer indusial valve usually with pale margin; spores with perispore deposited in retate pattern, appearing verrucose at low magnification. — Sulawesi ........ 3. D. celebica

4. Hairs on petioles, rachises and costae forming a dark reddish brown shaggy coat, hairs curved and bent downwards in respect to the orientation of the frond; some indurated bases may persist if hairs are abraded on the axes; lamina not strongly tapering basally, petioles relatively long; costules of fully expanded fronds usually abaxially with persistent layer of reddish brown undercoat, obscuring the colour of the epidermis. — Philippines........ 1. D. amorosoana

4. Hairs on petioles dense, with reddish to dark orange spreading hairs and paler woolly undercoat, becoming gradually thinner and paler towards costae; lamina notably to strongly tapering basally, petioles relatively short; costules of fully expanded fronds abaxially usually with hairs sparse or absent, colour of the epidermis visible. — Seram, Timor....... 5

5. Plants terrestrial with ± straight trunks; epidermis of costae and costules abaxially with atropurpureous to blackish epidermis, contrasting strongly with the lamina; largest segments elongate with blunt tips; spores with retate perispore, appearing verrucose at low magnification. — Seram...................................... 4. D. ceramica

5. Plants starting as hemi-epiphytes on other tree ferns, trunk often bent where plant germinated on host; epidermis of costae and costules abaxially green in fresh material, yellowish to stramineous when dried, not contrasting strongly with the lamina; largest segments ovate-oblong with acute to short-acuminate tips; spores with evenly distributed perispore, appearing smooth at low magnification. — Timor.................................. 6. D. timorensis