71. Asplenium semivarians Viane & Reichstein, Pterid. New Millennium. 78. 2003.
近变异铁角蕨 jin bian yi tie jiao jue
Rhizome erect, short, scaly; scales brown to dark brown, 2-4(-5) × ca. 0.5 mm. Fronds caespitose, (5-)10-25(-30) × (1-)3(-7) cm; stipe semiterete, (1.2-)2-5(-8) cm, adaxially green and sulcate, abaxially entirely green (small fronds) or dark brown for 1/4-3/4 of its length (in large fronds into lower part of rachis), with scales similar to those on rhizome; lamina ovate, apex acute-acuminate, 2- or 3-pinnate at base; pinnae (6-)10(-14), subopposite to alternate, with stalks 1-2 mm, triangular to ovate, 2-4(-5) cm, lowest usually reduced, base asymmetrical, acroscopically truncate, basiscopic side cuneate, apex obtuse to acute; segments 2-4 pairs, alternate, anadromous, basal acroscopic segment largest and free, others usually adnate to costa, broadly ovate to orbicular. Fronds herbaceous, green; rachis green, sulcate adaxially, abaxially often shiny castaneous at base but green toward apex; lamina with 3- or 4-celled uniseriate gland-tipped hairs, average guard cell length 37-40 µm. Sori several on each pinna, medial on subtending vein, often confluent at maturity, oval-linear, 1.5-3 mm; indusia membranous, repand to entire, opening toward costule or to costa. Spores with lophate (cristate-alate) perispore, average exospore length 24-27 µm. Plants diploid sexual: 2n = 72.
On rocks or trees in forests; 1200-2500 m. Yunnan [India, Philippines, Sri Lanka; mountains of tropical Africa].
The range of Asplenium semivarians is not well known due to confusion with similar species of the A. varians complex. It may also occur in Malaysia (Johore), but the single specimen, cited by Morton under A. varians, needs further study. Experimental hybridization and micromorphology have shown (Viane & Reichstein, Pterid. New Millennium, 73-105. 2003) that it is different from diploid A. tenuicaule and that it is an ancestor of true A. varians. Asplenium semivarians is known from S India as diploid A. varians (e.g., Manickam & Irudayaraj, Cytol. Ferns W. Ghats, 38, 71. 1988; Pterid. Fl. Nilgiris, 130-131. 2003) or as diploid A. laciniatum (Bir & Irudayaraj, Fern Gaz. 16: 186-187. 2001). Luxurious plants become almost tripinnate. This species can be distinguished from similar taxa by its diploid chromosome number, its alate perispore with the middle perispore lacking in the areoles (zones between the ridges), and the smaller exospore and guard cells.