Mature spores of four pleurocarpous mosses in the Canary Islands: ultrastructure and early germination stages

Abstract

We describe the morphology and ultrastructure of mature spores of four epiphytic pleurocarpous mosses from the Canary Islands laurel forest: Leucodon canariensis (Brid.) Schwägr., Cryptoleptodon longisetus (Mont.) Enroth., Neckera cephalonica Jur. & Unger., and N. intermedia Brid. The two Neckera species are strictly isosporic, while the capsules of L. canariensis contain viable spores of two classes—uni- or multicellular, medium-sized (26–48 µm) spores; and multicellular, large (50–94 µm) spores. Also in C. longisetus, two different kinds of viable spores are produced in the capsules—unicellular, small spores (11–24 µm) and medium-sized (26–35 µm) spores. These observations suggest anisospory for both species. Intracapsular spore germination is observed in three species, but not in N. cephalonica. Spore wall stratification of the four species follows the typical pattern for mosses—perine, exine and intine. The ornamentation pattern is uncharacteristic, with perine variously papillose. All spores are inaperturate. The cytoplasm shows abundant lipid-like inclusions and chloroplasts with well-developed thylakoids. The taxonomic significance of the spore characteristics is discussed.