A conspectus of the native and naturalized species of Nephrolepis (Nephrolepidaceae) in the world Hovenkamp PH Miyamoto F Blumea 2005 50 279 322 BBLNZ (F. Ballard) Hovenkamp & Miyam Hovenkamp & Miyam F. Ballard Polypodiopsida Nephrolepidaceae Nephrolepis Plantae Polypodiales 18 297 Tracheophyta variety pumicicola pumicicola  Differs from the typevariety: Rhizome thin, upright, up to 10 cmhigh, fronds stiffly erect, narrow, to 120 by  3-3.5 cm;pinnae perpendicular to rachis.  Distribution - Africa: Sao Tome,  Cameroon.  Habitat & Ecology - At low elevations to  1500 m,terrestrial, often in crevices of young volcanic rocks.  Note - This variety is restricted to the Gulf of Guinea. It is relatively easy to recognize when compared with the in Africa widespread species N. undulataby its perennial habit, the stem-forming rhizome (but this may not be evident in all specimens) bearing rigidly erect fronds with numerous, small pinnae at right angles to the plane of the rachis. None of these characters provide a clear basis for a distinction as a separate species, as all occur to varying degrees in N. cordifoliafrom other regions. Moreover, some specimens also collected on lava show a more relaxed habit, with less distinctly horizontal pinnae and a less stiffly erect habit, and thus are closer to typical N. cordifolia(e.g.,   Benl& Benl FP54, Fernando Po;   Mildbraed10678).For these reasons, we include this as a variety in N. cordifolia   . However, a number of collections from the  VirungaMountains( Congo) include plants forming small tufts (   Burtt3280, K,"frequent inside crater") as well as plants with the typical rhizome of N. undulata(   Burtt3117, K,"lava plains"). Clearly, more detailed investigations are necessary to decide whether N. pumicicolais here rightly included in N. cordifolia, or whether it should be included, as a perennial variety, in N. undulata   . 923900991 2005-01-01 2005-12-31 2005-01-01 K Keay 28655 Thailand 18 297 Type 923900994 2005-01-01 2005-12-31 2005-01-01 Benl & Benl FP 54 Guinea Fernando Po; 18 297 Fernando Po; 923900975 2005-01-01 2005-12-31 2005-01-01 Mildbraed 10678 Guinea 18 297 Fernando Po 923901006 2005-01-01 2005-12-31 2005-01-01 K Burtt 3280 Guinea 18 297 Fernando Po 923900999 2005-01-01 2005-12-31 2005-01-01 K Burtt 3117 Guinea 18 297 Fernando Po