Fig. 2.

(A–D) Labellum of Bifrenaria aurea (K54349) showing short, conical papilla-like trichomes (A), conical to obpyriform papillae (B) and stages in trichome formation (C, D). The latter process commences with the development of a small protrusion upon the papilla (C). Further development of this protrusion results in the formation of a conical papilla and eventually a trichome (D). Scale bars: A = 500 μm; B = 100 μm; C = 25 μm; D = 100 μm. (E, F) Labellar surface of Bifrenaria tetragona (KLD200502) showing conical papillae with longitudinal, cuticular striations (E) and stages in the development of unicellular trichomes (F). Scale bars: E = 10 μm; F = 200 μm.