Polystichum luctuosum (Kunze) T. Moore

Roux, Jacobus P., 2001, A review of the fern genus Polystichum (Pteropsida: Dryopteridaceae) in Madagascar and the Mascarene region, Adansonia (3) 23 (2), pp. 265-287 : 276-278

4. Polystichum luctuosum (Kunze) T. Moore

Index Fil.: 95 (1858); Christensen, Dansk Bot. Ark. 7: 68 (1932); Tardieu, Fl. Madag., fam. 5: 320 (1958); Roux, Bull. Nat. Hist. Mus. Lond. (Bot.) 30: 37 (2000). — Aspidium luctuosum Kunze, Linnaea 10: 548 (1836). — Polystichum lobatum var. luctuosum (Kunze) Christ, Ber. Schweiz. Bot. Ges. 3: 34 (1893). — Types: Ecklon s.n., in monte Katriviersberg in sylvis, (syn-, LZ, delet.); Ecklon s.n., ad fontes fl. Katrivier prope Philipstown, in sylvis montium, (syn-, LZ, delet.). Aspidium tsus-simense Hook., Sp. Fil. 4: 16 (1862). —

Polystichum tsus-simense (Hook.) J. Sm., Hist. Fil. :

219 (1875). — Type: Wilford s.n., Island of Tsus

Sima, in the Straits of Korea (holo-, K [2 sheets];

NBG!-photo).

Plants terrestrial, epilithic, or rarely as low-level epiphytes. Rhizome short, erect to suberect, to 10 mm in diameter, densely beset with roots, persistent stipe bases, and paleae, the paleae castaneous, chartaceous, the larger paleae broadly attached, ovate, narrowly ovate, or lanceolate, cordate, with long twisted uniseriate, glandtipped hairs on the apical margin and surface, the apex flagelliform, terminating in an oblong thinwalled cell, to 10.5 × 3.3 mm, the smaller shortstalked, narrowly triangular to subulate, cordate, the margins proximally with numerous long and twisted uniseriate hairs, distally with widely spaced apically and basally directed marginal outgrowths that become smaller apically, the apex flagelliform, terminating in a small thin-walled cell. Fronds crowded, caespitose, 7-16 per plant, suberect to arching, to 0.93 m long; stipe proximally castaneous, stramineous distally, adaxially sulcate, to 450 mm long, to 5 mm in diameter, densely paleated, the proximal paleae castaneous, chartaceous to crustaceous, broadly attached, ovate, cordate, the margins proximally entire or with a few short and/or long uniseriate hairs, distally with numerous multicellular hairs as for the rhizome paleae, the distal paleae short-stalked, narrowly oblong, narrowly triangular or subulate, cordate to hastate, the margins bearing a few long and/or short multicellular hairs proximally, distally with widely and irregularly spaced outgrowths reduced in size and number towards apex, the apex flagelliform, terminating in a small thin-walled cell, to 15 × 1.5 mm; lamina 2-pinnate to 2-pinnate-pinnatifid, with up to 25-stalked pinna pairs, to 480 mm long, firmly herbaceous to coriaceous, olive-green adaxially, paler abaxially, narrowly ovate to ovate, the proximal pinnae slightly reduced, often somewhat deflexed; rachis stramineous, adaxially sulcate, densely paleated, the paleae dark brown to black, glossy, chartaceous to crustaceous, short-stalked, narrowly triangular to subulate, cordate to hastate, the auricles usually bearing long and twisted multicellular and uniseriate hairs some of which terminate in a thin-walled cell, the margins either distally with short, widely and irregularly spaced outgrowths that reduce in size and number towards the apex, or more or less entire in smaller paleae, to 7 mm long; pinnae shortstalked, 1-pinnate to 1-pinnate-pinnatifid, with up to 12-stalked pinnule pairs, narrowly lanceolate, proximally widely spaced, distally often somewhat overlapping, to 173 mm long; pinnarachis stramineous, adaxially sulcate, densely beset with paleae similar to, but less complex than those on the rachis; pinnules widely spaced to overlapping, the proximal acroscopic pinnule the largest, often significantly longer than the next, to 40 mm long, to 12 mm wide, inaequilateral, narrowly trullate to rhomboid, basiscopically cuneate, acroscopically truncate and auricled, often somewhat falcate, lobate-serrate, aristate, the proximal pinnules short-stalked, often acroscopically incised to or nearly to the costa, the costa adaxially sulcate, glabrous, abaxially sparsely beset with castaneous, chartaceous, narrowly triangular-hastate to subulate-hastate paleae, cordate to cordate-imbricate, proximally with long and/or short filiform outgrowths that often terminate in a thin-walled cell, the apex always terminating in a small thin-walled cell, to 0.3 mm long. Venation obscure. Sori circular, c. 1.2 mm in diameter; terminal or near-terminal on abbreviated vein branches, essentially uniseriate; sporangium stalk eglandular, capsule with 10(-13-)19-indurated annulus cells; indusium peltate, circular, entire, repand or crenulate, persistent, brown, pale brown and often dark-centred before drying, cupulate when dry, maximum radius 0.5(-0.73-) 0.95 mm. Spores 32 per sporangium, brown, the perispore unevenly folded to form narrow and broad reticulate ridges, the ridges and areas between ridges echinulate, spicu-

C

late or verruculate, exospore 30(-38.84-)50 × 22(-28.2-)36 µm. Chromosome number 2n = 123, apogamous. — Figs. 3J,K.

MATERIAL EXAMINED. — MADAGASCAR: Humbert & Swingle 4798, environs d’Ambositra, Mt. Vatomavy ( BM, P); Perrier de la Bâthie 13656, massif de l’Andringitra, 1200 m ( P); Herb. Jard. Bot. Tananarive 3229, Merina ( P); H. P. B. s.n., Manongarivo, 1200 m ( P). — LA RÉUNION: Cadet 4129, Thermes de Cilaós, 1200 m ( P).

DIAGNOSTIC FEATURES AND RELATIONSHIPS. — Diagnostic of Polystichum luctuosum is the olivegreen colour of the adaxial surface of the lamina and the darker veins seen in live plants. It is also separated from other taxa in the region by the usually very dark and narrow paleae occurring along the stipe and rachis. The larger rhizome and stipe base paleae bear long filiform outgrowths along the margin and paleae surface. Indusia are large, persistent, and entire, and take on a cupulate form when mature. Polystichum luctuosum is furthermore a triploid apomict with 32 spores per sporangium and has a somatic chromosome number of 2n = 123. Polystichum luctuosum belongs to section Xiphopolystichum Daigobo.

VARIATION. — Polystichum luctuosum shows little variation in stipe, lamina and basal pinna length within the study area. A comparison of these parts with Asian material shows that African (including Madagascar) plants are slightly larger than plants from Asia ( ROUX 1998).

DISTRIBUTION AND ECOLOGY. — The species occurs on La Réunion and the central parts of Madagascar at elevations to 1200 m. Polystichum luctuosum also occurs on the Indian subcontinent, extending to Pakistan, China, Vietnam, South Korea and Japan (Honsyu, Sikoku and Kyusyu). In South Africa, Polystichum luctuosum occurs from the Eastern Cape, through KwaZulu-Natal to the north-eastern parts of the Free State, Mpumalanga and the Northern Province. It also extends to the lower western parts of Lesotho and the higher lying part of Swaziland with isolated populations occurring along the eastern escarpment in Zimbabwe.

Polystichum luctuosum mostly occurs epilithically along streams, but often also as a low-level epiphyte in moist forests. Plants often also grow on rocks away from water and in fairly dry conditions.

Figures

Fig. 3. — Stipe and lamina paleae in Polystichum species. — Polystichum ammifolium: A, stipe palea, Boivin 822 (B); B, lamina palea (adaxial surface), Rakolomalala s.n. (P); C, basal part of B showing the cellular structure. — Polystichum crinulosum: D, stipe palea, s.coll. s.n. (P); E, apex of D showing the cellular structure; F, rachis palea, s.coll. s.n. (P); G, apex of F showing the cellular structure. — Polystichum kalambatitrense: H, stipe palea. Humbert 12158 (P); I, lamina palea (abaxial surface), Humbert 11914 (P). — Polystichum luctuosum: J, stipe palea. Roux 2268 (NBG); K, lamina palea (abaxial surface), McDonell 34 (BM).