1) Fern genus 2) Genus pityrogramma 
(from the article `fern`) ...another of the following six soral arrangements: (1) A linear arrangement of sporangia along veins, avoiding the leaf area between the veins, is ...
[n] - terrestrial tropical ferns having fronds with powdery yellowish or white undersides
genus Pityrogramma noun terrestrial tropical ferns having fronds with powdery yellowish or white undersides; sometimes placed in family Polypodiaceae or Adiantaceae