Figure 3

Cryo-SEM images of the horse-chestnut bud scales and secretion. (A) Cross-section (freeze-fracture) of bud scales and embedded secretion. The inset indicates the fracture position on the bud. See the close-up views in (F) and (G). (B–E) Details of the bud secretion cross-section after freeze-fracture (B,C), pulled into a filament indicating a fibrous component (D), and the non-structured surface (top view in E). Note the presence of micelle-shaped structures included in the amorphous layer of secretion (B,C). (F,G) Freeze fracture of bud scales and secretion covering the secretion-releasing colleters. (H–K) Solvent treatments: the bud scale surface covered with numerous collapsed colleters after washing with acetone and total removal of secretion (H,I), partially collapsed colleters after washing with ethanol leaving residues of secretion (J,K). (L–O) The interface of bud secretion droplets and normal glass, after keeping the secretion at 22.7 °C, 46.6% RH (H,I), at 22.6 °C, 0.3% RH (J), and at 22.4 °C, 99.3% RH (M). (P,Q) The secretion droplet in contact with Teflon tape, top (P) and side view (Q). (R) The interface between the bud secretion and a cockroach forewing showing a wrinkled, self-organized pattern at the edge. (S) A mite stuck to the bud, having the integument partially covered with bud secretion and distal legs entangled with secretion and trichomes. bs bud scale, co colleters, cw female cockroach forewing, gl glass, se secretion, sp self-organized pattern, te teflon, tr trichomes. Scale bars: (A) 200 µm; (B,D,L) 5 µm; (C,E,G,M,N,O,P) 500 nm; (F,I,J,K,S) 20 µm; (H,Q) 100 µm; (R) 2 µm.