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

<p>A–B: SEM, C–E: TEM. A) Spore subellipsoidal. Verrucae large, irregular in shape and size. B) Primary elements irregularly fused, occasionally forming large bands. Secondary processes scarce, irregularly present on the verrucae. C) Perine electrondense, elements connected by an electrondense basal layer. Exine thick, electrontranslucent, locally separating into parallel lamellae (asterisk). Intine electrontranslucent, thick, two layered. D) Cytoplasm granular. Chloroplasts with well developed thylakoids, often with starch. Abundant lipid droplets of two different types, some electrontranslucent, undisolved, the others electrondense and partially or almost totally dissolved. E) Detail of sporoderm structure showing two layered intine, outermost layer granular, innermost layer granular-fibrillar. Abbreviations: bPe: basal layer of perine material; Chl: chloroplasts; CW: cell wall; dL: partially dissolved, electrondense lipidic droplets; dPe: detached perine elements; E: exine; fPe: fused perine elements; I: intine; Ie: external layer of the intine; Ii: internal layer of the intine; N: nucleus; Pe: perine elements; sPe: perine secondary processes; S: starch grains; uL: undissolved, electron translucent lipid.