Spore ultrastructure of <i>Orthotrichum affine</i> (type I).

<p>A–B: SEM, C–D: TEM. A) Subspherical spore ornamented with irregular primary elements forming verrucae B) Detail of the spore showing primary elements covered with abundant, irregular secondary processes C) Verrucae are ornamented with abundant secondary processes. Perine elements appear connected by a relatively thick basal layer of electrondense material. Exine electrontranslucent, clearly polarized, proximally thin and compact, distally enthickened and locally separating into parallel lamellae. Plastids with well-developed thylakoids, fusiform, loosely disposed in the cytoplasm. Small starch grains present within the plastids. D) Wall structure of a spore in detail. Distal part of the spore with thick exine. Intine two-layered, outer layer granular, inner layer fibrillar, undulate, and more electrondense. Abbreviations: bPe: basal layer of perine material; Chl: chloroplasts; dL: partially dissolved, electrondense lipidic droplets; dPe: detached perine elements; E: exine; I: intine; Pe: perine elements; sPe: perine secondary processes; S: starch grains.