Spore ultrastructure of <i>Orthotrichum ibericum</i>.

<p>A–B: SEM, C–E: TEM. A) A subellipsoidal spore (usually slightly flattened), irregularly ornamented with perine elements, leaving large naked areas. B) Detail of the sporoderm showing perine primary elements (verrucae and baculi) covered with secondary processes (scattered papillae). C) A bicellular spore showing a sporoderm with sparse perine elements and polarized intine (proximally much thicker), and a granular cytoplasm with loosely packed chloroplasts and lipidic droplets (usually sparse in this species), some electrondense and partially dissolved, more often medium-electrondense, undissolved. D) A spore showing the sporoderm with two continuous intine layers and an occasional, internal, electrontranslucent, granular layer locally present; and exine, electrontranslucent and extensively separating into parallel lamellae. In the cytoplasm the chloroplasts appear with abundant plastoglobuli. E) Detail showing the sporoderm with a very thin basal layer connecting perine elements; the exine extensively separating into parallel lamellae (asterisks); and the intine stratification: an outermost layer amorphous, an inner granular layer, and a discontinuous granular, electrontranslucent, innermost layer. Abbreviations: bPe: basal layer of perine material; Chl: chloroplasts; CW: cell wall; dL: partially dissolved, electrondense lipidic droplets; E: exine; I: intine; Ie: external layer of the intine; Ig: innermost discontinuous intine layer; Ii: internal continuous layer of the intine; N: nucleus; Pe: perine elements; sPe: perine secondary processes; pg: plastoglobuli; S: starch grains; uL: undissolved, electron translucent lipid droplets.