Compilation
Pteris decursiva

The commonly held view that Cheilanthes farinosa is an extremely complicated complex of many different groups seems to me exaggerated. The material from Yemen appears to me undoubtedly conspecific with the African material so we are not concerned with the difficulties in Asia. The various races marked by different spore types, cytology, and different chromatographic analyses do not seem to correlate with the gross morphology and geography. The view is taken that at least in Africa, it is best to retain them under a single wide species, but it is necessary to discuss the work which has been done.Manton et al. (K.B. 18: 553–565 (1966)) recognised groups, three of which occur in E Africa:1) an apogamous triploid with “smooth” spores, having lamina ovate-lanceolate with basal pinnae shorter than the next above, pinnae and pinnules more spaced, lanceolate stipe scales, and dark-striped rhizome scales (this they considered typical C. farinosa matching Vahl’s figure)2) a sexual tetraploid with ‘spinulose’ spores (64 per sporangium) having the lamina more triangular with basal pinnae the longest, pinnae and pinnules more closely spaced, the stipe scales with or without a dark stripe, and3) a group with the ultimate segments with venation impressed above giving a bullate appearance, stipe scales yellowish-brown and broadly ovate and a broad continuous (not lobed) indusium. This was not sampled cytologically.Pichi Sermolli described Aleuritopteris afra from Kilimanjaro with narrowly oblong-lanceolate lamina with two lower pairs of pinnae more or less equal, rhizome scales without black stripes and a continuous erose-margined indusium.Saiki (J. Phytogeogr. & Taxon. 32: 81–90 (1984)) has described several new species based on a few specimens from various herbaria but has not examined the material available at BM, K etc. He gives a key and describes work on the spores and chromatographic analysis (J. Phytogeogr. & Taxon. 32: 91–98 (1984)). It is clear from this there are races within C. farinosa but these appear to be poorly correlated with gross morphology and geography.E. G. Andrews l.c., divides C. farinosa into groups but unfortunately although she lists the sheets of C. farinosa she has seen, she does not assign them to her groups.Group 1. Up to 40 cm tall; lowermost pinnae appearing shorter than pair above; farina yellow-green; stipe densely scaly with scales light brown with darker stripes continuing up the rhachis; rhizome scales darker brown, dark striped; indusia discontinuous, fimbriate-lacerate; 64 spores per sporangium, reticulate-cristate. Restricted to Uluguru Mts.Group 2. Fronds narrowly triangular to lanceolate; lowermost pinnae ± equalling the pair above; farina white; veins not impressed on upper surface; 64 spores per sporangium, reticulate-cristate. High elevations on mountains. This corresponds with C. afra (Pic. Serm.) Kornaś.Group 3. Similar to Group 2 in lamina characters but with veins deeply impressed above (“bullate surface”) rhizome scales rust-coloured, not striped, narrowly lanceolate; stipe scales golden-brown, broader and ovate, restricted to lower part; spores 64 per sporangium, spongy reticulate. On mountains Kilimanjaro, Ruwenzori, Mt. Kenya etc., 2700–3330 m. This is the third group recognised by Manton et al.Group 4. Fronds broader than in groups 2 and 3 with pinnae wider and more closely spaced on the rhachis; farina white; rhizome scales dark-striped or not; stipe scales dark golden brown, ovate to lanceolate, hair-pointed. Indusia continuous and entire, extended from a recurved leaf margin, inconspicuous at maturity. Spores 64 per sporangium, spongy reticulate. Kenya 2670–3600 m. Andrews op. cit., says that this is the least distinct group and appears to be the sexual tetraploid of Manton et al.Group 5. Similar to group 1 but up to 1 m tall and more robust; farina white; stipe scales dark to golden brown sometimes slightly dark striped; no scales on rhachis; indusia continuous or discontinuous; 32 spores per sporangium, various but usually spongy/reticulate. Corresponds with the apogamous triploid of Manton et al. and assumed to be typical C. farinosa (Forssk.) Kaulf. and the same as A. decursiva (Forssk.) Saiki. Andrews states this is the most distinctive of all the groups with its scaly rhachis and yellowish-green farina and seems closely related to Nigerian material determined as C. anceps Blandford by Jarrett and matches its spores. It also corresponds to A. flava Saiki so far as his type Schlieben 3223 is concerned, but Schelpe 3930 (from Victoria Falls) also cited by Saiki has different spores and is a sexual tetraploid (fide Manton et al.). Panigrahi has also reported C. anceps to be a sexual tetraploid but considered it not to occur in Africa. Actually nearly all the material annotated as C. anceps has pure white farina. Schippers (Fern Gaz. 14: 179 (1993)) has cited Schlieben 3223 as C. anceps.