Selaginella njam-njamensis appears to be Africa's most common species of the Tetragonostachys. It can be found from southeastern Mali, northwestern Benin, into central Nigeria, in the west of Cameroon and the Central African Republic, extreme southern Sudan, southwestern Ethiopia, southward in northeastern Zambia, throughout Malawi,
northern Mozambique, and from northern Zimbabwe into eastern Botswana and adjacent northeast South Africa.
While the species is dimorphic, it is only slightly so and may be easily confused with monomorphic species. This
closeness in appearance to monomorphic species may suggest that its habitat is less xeric than that of the more
pronunced dimorphic species. D. J. Humbler, of the Nigerian College of Arts, Science and Technology in Ibadan, Nigeria, in his article titled A Poikilohydrous, Poikilochlorophyllous Angiosperm from Africa, in Nature (#191, pages 1415-1416, published 30 September 1961, notes that the species inhabits thin soil mats on inselbergs
(This is an image of an inselberg in Mali http://en.wikipedia.org/wiki/File:Hand_der_Fatima.jpg
(monadnocks) and appears to be poikilohydrous (which means that it can recover from being dried out). However,
the species occurs in areas of summer rains that may vary from 750 to 1000 millimeters (30-39 inches) annually,
as well as upon very faulted gneiss outcrops, with feeder springs that flow out into marshes (Imatong Mountains of
Southern Sudan), at elevations that may range from 400 to 1200 meters (1312 to 3937 feet). Some plant associated with its occurrence are: Loudetia simplex, Aloe labworana, Aloe mawii, Vigna racemosa, Euphorbia ramulosa and E. graniticola, Xerophyta species, and assorted annual species.
Like most monomorphic species, S. njam-njamensis has strobili that are upright rather than prone as seems to be the case with the majority of African/Madagascaran species.
Despite its abundance there appears to be no images of living plants on the internet. There is only one fragment of a dried up branch system with rhizophores available. http://sweetgum.nybg.org/vh/specimen.php?irn=501514
There is a drawing of the plant with possible strobili (indistinct) and a microphyll on document page 44 (page
26/30 on toolbar) of this large PDF file. Allow it time to load before attempting navigation. http://www.sabonet.org.za/downloads/31_nyika/list/a_nyikalist_p19-48.pdf