Dryopteris manniana (Hook.) C.Chr.

Roux, Jacobus P., 2011, The fern genera Dryopteris and Nothoperanema (Dryopteridaceae) in Madagascar and neighbouring Indian Ocean islands, including Saint Paul, Adansonia (3) 33 (1), pp. 7-67 : 38-42

5. Dryopteris manniana (Hook.) C.Chr.

( Figs 17 ; 18 )

Index filicum: 276 (18 Nov. 1905). — Polypodium mannianum Hook. , Species filicum 4 (15/16): 253 (1863). — Phegopteris manniana (Hook.) Kuhn, Filices africanae: 123 (Oct. 1868).

— Type: Fernando Po, on the peak, 2000 ft, 1860, G. Mann s.n. (holo-, K!; iso-, K!).

OTHER MATERIAL EXAMINED. — Madagascar. Ambatofitorahana, 1700 m, IX.1956, Bosser 9787 ( P 00349514 ). — Centre, Forêt de Manjakatompo , versant E de l’Ankaratra, VII.1953, Capuron 70RC ( P 00349509). — Rahobevava, 960 m, 11.III.1951, Cours 4292 ( P 00349513). — Madagascar, Cowan s.n. ( BM 000800961, A only, BM 000800962), Ankafana, Cowan s.n. ( BM 000605571). — Madagascar, Cowan s.n. ( BM 000605576). — Prov. Imerina, VII.1880, Hildebrandt 3529 ( BM 000800984). — Massif du Kalambatitra (Centre-Sud), Mont Kalambatitra et ses abords et mont Analatsitendrika, forêt ombrophile (sur latérite de gneiss), 1500- 1750 m, XI.1933, Humbert 11875 ( P 00349512). — Tanala, V.1880, Kitching s.n. ( K, B only). — Antananarivo, Ankazobe, Manankazo, réserve spéciale d’Ambohitantely, environ 8 km au Nord-Ouest d’Ankazobe, 18°10’S, 47°17’E, 1200- 1650 m, Rakotondrainibe 348 ( P 00349515).

DESCRIPTION

Plants terrestrial.Rhizome erect to short-decumbent, mostly unbranched, up to 8 mm in diameter, set with roots, closely spaced stipe bases, and scales, the scales brown to ferrugineous, chartaceous, broadly attached, subulate, up to 22 × 3 mm, the margins closely set with short teeth, the apex filiform, terminating in an oblong cell. Fronds 4-7 per plant, caespitose, arching, up to 1.0 m long; stipe greenish to stramineous, shallowly sulcate adaxially, up to 480 mm long and 5 mm in diameter, proximally densely scaled, moderately scaled higher up, the scales stramineous to ferrugineous, chartaceous, the larger scales broadly attached, up to 15 × 4.5 mm, the smaller scales short-stalked, cordate to cuneate, the margins denticulate, basally frequently with one or more filiform outgrowths, often with scattered glands, the apex filiform, terminating in an oblong cell; lamina herbaceous, ovate, up to 525 mm long, to 2-pinnate-pinnatifid, anadromous, catadromous towards the apex, with up to 12 petiolated pinna pairs, proliferous, generally with one or more scaled buds adaxially along the rachis near the lamina apex, often also with buds on the pinna-rachis in larger fronds; rachis greenish to stramineous, adaxially sulcate, narrowly winged towards the apex, moderately scaled, the scales ferrugineous to stramineous, chartaceous, sessile or short-stalked, filiform to lanceolate, up to 7 × 1.8 mm, cordate to narrowly cuneate, denticulate, basally frequently with one or more filiform outgrowths, higher up closely set with short teeth, the apex filiform, terminating in an oblong cell; pinnae petiolate, the petiole up to 18 mm long; basal pinna pair inaequilaterally ovate, narrowly ovate to oblong-acuminate towards the lamina apex, up to 250 × 95 mm, to 1-pinnatepinnatifid; basal pinna pair mostly the longest, basiscopically developed, opposite to alternate, basally widely spaced, more closely spaced towards the lamina apex and often imbricate, with up to 3 pairs of petiolated pinnules; pinna-rachis adaxially shallowly sulcate, the sulcus confluent with that of the rachis, pronounced abaxially, narrowly winged for most of the length, abaxially sparsely to moderately scaled, the scales stramineous to ferrugineous, chartaceous, sessile or short-stalked, filiform to narrowly oblong, up to 5 × 1 mm, cordate to narrowly cuneate, dentate, basally frequently with one or more filiform outgrowths, the apex filiform, terminating in an oblong cell; pinnules petiolate, the petiole up to 2 mm long, symmetric or inaequilaterally narrowly ovate to ovate, up to 50 × 17 mm, basiscopically decurrent, pinnatifid, acroscopic pinnule on the basal pinnae up to 56 × 23 mm, not or slightly imbricate, the lobes broadly oblong-obtuse, shallowly lobed, dentate, glabrous adaxially, abaxially rarely glandular, the glands (56-)62(-72) µm long, sparsely set with hairs and scales along the veins, the hairs moniliform, often with a unicellular gland near the base, the scales stramineous, chartaceous, short-stalked, the stalk often glandular, filiform to linear, up to 2 mm long, repand to dentate, the apex filiform, terminating in an oblong cell. Venation anadromous, becoming catadromous towards the lamina and pinna apex, pinnately branched in the lobes, evident, ending in the teeth near the margin, the endings mostly slightly enlarged. Stomata mostly of the polocytic type, (40-)56(-70) mm long. Sori circular, inframedial on unmodified fertile vein branches, discrete at maturity, up to 1.5 mm in diameter; sporangium stalk simple or haired, capsule with (11-)14(-18) indurated annulus cells; exindusiate. Spores ellipsoidal, monolete, perispore forming short and long ridges, ruminate, (40-)44(- 58) × (26-)30(-32) mm. Chromosome number: 2n = c. 164 (Vida in Widén et al. 1973).

DIAGNOSTIC FEATURES AND RELATIONSHIPS

Diagnostic of Dryopteris manniana is the scaled proliferous buds borne adaxially on the rachis, mostly near the lamina apex, the denticulate scales, and the exindusiate sori. A micromorphological feature separating it from other Dryopteris species is the stoma size, which supports it being tetraploid.

VARIATION

Morphologically, the species appears to be stable throughout its distribution, with little variation of significance having been observed.

DISTRIBUTION AND HABITAT

Dryopteris manniana is widespread in sub-Sahara Africa occurring in West-, East-, southern Africa, and in Madagascar. It chiefly occurs in moist montane forests, at elevations ranging from 1400 m in Kenya and Uganda to 2249 m along the Kikuyu Escarpment in Kenya. In Madagascar, it is known from elevations ranging between 960 and 1750 m ( Fig. 16 ).

Figures

FIG. 17. — Specimen of Dryopteris manniana (Hook.) C.Chr., Humbert 11875 (P00349512). Photo: MNHN, Paris Herbarium, 2009.

FIG. 18. — Indumentum of Dryopteris manniana (Hook.) C.Chr.: A, stipe scale; B, rachis scale; C, pinna-rachis scale; D-F, scale and hairs from abaxial lamina surface. Roux 2857 (NBG). Scale bars: A-D, 0.5 mm; E, F, 0.1 mm.

FIG. 16. — Distribution of Dryopteris comorensis (Tardieu) Fraser- Jenk.(z) and D.manniana (Hook.) C.Chr.(Δ) in Madagascar and neighbouring Indian Ocean islands.