Dicksonia blumei (Kunze) T.Moore

Lehnert, M. & Coritico, F. P., 2018, The genus Dicksonia (Dicksoniaceae - Cyatheales) in western Malesia, Blumea 63 (1), pp. 268-278 : 272

2. Dicksonia blumei (Kunze) T.Moore — Fig. 2b , 3a , 4a ; Map 1

Dicksonia blumei (Kunze) T. Moore (1860) 190, not sensu Christensen (1934) 223. — Balantium blumei Kunze (1848) 214. — Type: H. Zollinger 1894 (holo? LZ destroyed;lecto B-20_0138231,here designated;iso LE-00007994 (image), P-01415028, UC-414484 (fragment)), Indonesia, Java, without locality, without date.

Balantium chrysotrichum Hassk.(1856) 53. — Dicksonia chrysotricha (Hassk.) T. Moore (1860) 190. — Type: J.K. Hasskarl s.n. (lecto L-1258965, here designated), Indonesia, Java, ‘ Bogor Botanic Garden, and certainly at Mt Gedeh and other places’, 1855–1856.

Etymology. Named after Carl Ludwig Ritter von Blume (1796–1862), Dutch-German botanist and director of the Rijksherbarium in Leiden, who collected extensively on Java and neighbouring islands (1818–1827).

Tree fern, terrestrial. Trunks to 8(–10) m tall, to 12 cm diam, with old petiole bases, without skirt of old fronds. Adventitious buds not reported. Fronds to c. 400 cm long, ascending-arching, up to 12 per crown. Petioles 60–95 cm long, erect-ascending, dark brown, smooth to scabrous, basally densely covered with soft woolly hairs to 1.5 cm long, shiny golden to yellowish, grading distally into undercoat of matted ciliform to catenate, tortuous hairs to 1 mm long, with numerous protruding setiform hairs to 5 cm long, dark reddish brown, spreading, non-irritant, brittle, black bases usually sticking out from the undercoat. Laminae to c. 300 by 140 cm, tripinnate-pinnatifid, subcoriaceous to coriaceous, oblong-lanceolate, gradually reduced apically, widest pinnae at the middle, tapering towards the base; shiny dark green adaxially, paler green abaxially; weakly dimorphic with fertile parts more deeply dissected, may be fertile in any part but mostly in the centre. Leaf axes (rachises, costae and costules) mostly dark reddish brown, often becoming paler towards the costules, these yellowish brown, axes densely hairy, rachises adaxially with spreading reddish brown hairs, antrorsely curved yellowish white hairs, and dense grayish brown undercoat, abaxially with longer reddish brown hairs, spreading, fragile, indument of costae and costules gradually becoming shorter, softer and paler. Pinnae to 70 by 19 cm, oblong-lanceolate, subsessile to sessile, 10–14 pairs per frond, with attenuate tips, basal pinnae reflexed, more oblanceolate, c. 1/2(–1/3?) the length of largest pinnae. Largest pinnules (sterile ≈ fertile) 6.5–8.0 by 1.7 cm, triangular-lanceolate, with attenuate tips. Sterile segments to 12.0 by 4.5 mm, oblong to linear, ascending, sessile, proximal ones free, distal ones adnate, margins crenate to serrate, especially towards the acute tips; fertile segments to 12.0 by 4.0 mm, sessile, free to decurrently adnate, linear, contracted, with 2–4 pairs of sori on deltate lobes, segment tips sterile. Veins adaxially glabrous, abaxially only midvein weakly to strongly hairy, hairs whitish to partly reddish, flaccid, often catenate, to 2.5 mm long, lateral veins glabrous, mostly simple, only in proximal segments forked 1 or 2 times. Sori 1.8–2.0 mm diam, kidney-shaped when closed, circular when open, mostly (c. 75 %) on end of branched vein, the sterile lobe sticking out weakly to strongly below the sorus, if sorus on simple vein (c. 25 %) then on a lobe that is as wide as or wider than the outer indusial valve; outer indusial valve with pale yellowish to brown cartilaginous margin and notably darkened, sometimes blackish rim, inner valve concolorous brown with subentire to erose margin, the rim not darkened. Spores tetrahedral-globose with prolonged, depressed lobes, to 57 µm diam, exospore retate, appearing smooth, areoles filled up by perispore, perispore papillate-granulate to baculate.

Distribution — Sumatra (up north to Karo Plateau; Holttum 1963), Java and Bali.

Habitat & Ecology — In wet montane forests, often abundant in the understory, at 1200–2500 m (and higher?).

Vernacular name — ‘Blume’s bristly tree fern’, suggested herewith.

Additional specimens. INDONESIA, Bali, B. Pohen, Batukau National Reserve , S08°19'48" E115°04'48", 1700 m, 24 Mar. 1992, Afriastini 164 B1 ( K) ; ‘ Java Orientalis’, Tengger Mts, Wonosari , 1200–1300 m, June 1909, Mousset s.n. [Rosenstock exsicc. 72] ( STU, UC, W) ; Tankouban Prahou, Wawra 1191 ( W) ; Java, Halimum National Park , 28 Oct. 2011, Chen 2040 ( TAIF) ; Sumatra, SSE of Sibajak (c. N03°13'12" E98°31'12"), 1450 m, LÖrzing 5959 ( K) ; Sumatra, Gunung Singgalang (c. S00°24' E100°21'), 2134 m, 16 Jan. 1913, Matthew s.n. ( K) .

Notes — ‘ Dicksonia blumei C.Chr. ’ is often given as a later homonym, but Christensen (1934) actually just discussed Bornean plants under the correctly referenced name D. blumei (Kunze) T.Moore , which he pointed out to be quite different from Javanese plants and more similar to Philippine populations. These Bornean and Philippine plants were later described as D. mollis ( Holttum 1962) .

In the discussion of Balantium blumei, Kunze (1848) cites two more collections: “From Java I received it first from collector Sporleder (with the added observation that the trunk is 15 feet tall). Junghuhn collected it on Mount Dieng (t. de Vr.)” [personal translation from Latin]. His description, however, is referenced solely by the collection of Zollinger (“S[pecimen]. l[egit]. Zollinger”), so it is interpreted to be based largely or entirely on this collection. “ Cibotium magnificum de Vriese in litt.” was cited as synonym ( Kunze 1848) but seems to be unpublished and invalid.

In the description of Balantium chrysotrichum, Hasskarl (1856) specifically points out the soft hairs of the petiole and the trunk, which he reports to be used for the stopping of external and internal haemorrhages. He also mentions that some brown hairs are protruding from the woolly indument on the petiole, but without noting anything about them being irritating. The documented petiole characters are very useful for the distinction of D. blumei from D. mollis , which apparently always has irritant hairs and just a thin undercoat. Unfortunately, in most specimens the petioles are not or only fragmentarily preserved (i.e., bristly hairs broken off, or only upper petiole parts with less characteristic indument present), so more field observations are needed for validation.

Otherwise D. blumei and D. mollis have more or less the same general appearance in the field, with relatively thin trunks and long-stalked fronds with petioles and thicker frond axes covered in spreading dark brown to reddish brown hairs. In both species, the hairs inserted directly on the trunk differ strongly from those of the fronds, and are sometimes preserved in specimens as pale golden wool loosely attached to the petiole base.

Dicksonia blumei was also reported from Sulawesi ( Holttum 1963); the respective specimen (Sarasin 2030) was not seen by us. Most likely it can be attributed to the very similar D. celebica . Dicksonia blumei is currently the only Dicksonia known on Java, so an unspecified tetraploid plant from this island with n = 130 ( Lovis 1978) most likely belongs to this species. The species is also unique within the Malesian clade (sensu Noben et al. 2017) in having smooth spores rather than the areolate to foveate spores with retate perispore (‘verrucose’ sensu Holttum 1963) that are typical of this clade. Our scanning electron microscopic images indicate that the areolate exospore pattern is obscured by a thick perispore layer ( Fig. 2b ).

Figures

Map 1 Distribution of Dicksonia in western Malesia: D. amorosoana (O), D. blumei (D), D. celebica (Δ), D. ceramica (A), D. mollis () and D. timorensis (z). Map by R. Cámara-Leret.

Fig. 2 Spores of Old World Dicksonia. a. D. amorosoana, distal view, perispore largely lacking, with some mould spore contamination (Philippines, Mindanao); b. D. blumei, distal view, granular persipore filling up retate structure of the exospore (Indonesia, Java); c. D. celebica, proximal view, young spore with perispore only beginning to form near the laesura (Sulawesi, Indonesia); d. D. herberti, distal view (Australia, Queensland); e. D. mollis, distal view (type; Philippines, Mindanao); f. D. sciurus, proximal view (Papua New Guinea) d and f are shown to illustrate the putative fully developed condition of the perispore in a and e, respectively (from: a. Coritico FPC 016, BONN; b. Chen 2040, TAIF; c. Brambach 2036, BONN; d. Kessler 14249, STU; e. Elmer 9874, MICH; f. Lehnert 2886, BONN). — Scale bar: 10 µm.

Fig. 3 Lamina details of Malesian Dicksonia species. a. D. blumei; b. D. celebica; c. D. mollis; a1–c1. sterile pinnules, adaxially (note: a1 from distal part of pinna, b1 and c1 from proximal part of pinna); a2–c2. sterile segments, abaxially; a3–c3. fertile segments, abaxially (from: a. Chen 2040, TAIF; b. Brambach 944, BONN; c. Chen 3837, TAIF).

Fig. 4 Petioles and axes of Malesian Dicksonia. a. D. blumei; b. D. celebica; c. D. mollis; first row (a1–c1) axils between rachis and costa, abaxially; second row (a 2 –c 2) details of petioles, a 2 with hairs partially abraded, exposing the epidermis and the paler softer undercoat, c 2 with most hairs broken off on the right side (from: a. Chen 2040, TAIF; b. Brambach 944, BONN; c. Chen 3837, TAIF).