In Polygalaceae only the genus Epirixanthes comprising 7 species is entirely devoid of chlorphyll. However, there are other species in Polygala and Salomonia that also show reductions in photosynthetic surface, e.g. Polygala setacea (Long and Lakela 1971) or Salomonia ciliata (van der Meijden 1988).
Blume (1823) coined the genus name (on page 25) in describing Epirixanthes elongata, E. cylindrica and E. linearis (today synonymous to E. elongata) on page 82, considering them as parasitic plants close to Orobanchaceae. The genus name has undergone frequent changes in spelling e.g. Epirizanthes and Epirizanthe (by Blume himself on herbarium sheets (after van der Meijden 1988) and in a later publication in the Flora of Java (after Penzig 1901)), Epirhizanthus (Martius 1842), Epirrhixanthes (Penzig 1901, Furman and Trappe 1971), Epirrhizantes (Wirz 1910), Epirrhizanthes (van der Pijl 1934), Epirhizanthes (Schmucker 1959), until van der Meijden (1988) attempted to clear this confusion in a footnote. Ironically, van der Meijden (1988) also misspelled the name exactly in that passage which should clarify the issue as ‘Epirixanthus’, although throughout his treatment he used the correct, oldest spelling (Epirixanthes). Hence, it is well understandable that even in rather recent publications misspellings are still in use.
Epirixanthes is closely related to Salomonia, in which it often has been included. However, not only the achlorophyllous habit but also flower, stamen and fruit characterisics differ between the two genera (Verkerke 1985, van der Meijden 1988, Eriksen 1993a, b).
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