FIGURE 2. Light microscopy of specimens of Pteridium subjected to diaphanization: A–C: P. arachnoideum subsp. arachnoideum s. str. (Schwartsburd 2255), D–G: P. arachnoideum subsp. campestre (Schwartsburd 2411). A, D: stomatal guard-cells, pointed by black arrows, B, E: veins ("V") and laminar tissue between the veins, abaxially (glabrous in P. arachnoideum subsp. arachnoideum (B), and obscured by gnarled hairs in P. arachnoideum subsp. campestre (E)), C, F: margins of the infertile pseudo-indusia. G: detail of a gnarled hair, pointed by black arrow. Bars = 50µm for all micrographs. Photograph by K.L.B. Lopes-Mattos.