Pollen wall development in Cryptomeria japonica (Taxodiaceae)

Pollen wall development in Cryptomeria japonica was observed by scanning an d transmission electron microscopy. The pollen of C japonica is characteriz ed by a non-saccate, projecting papilla. The exine of C. japonica consists of the outer granular ectexine and the in ner lamellated endexine. At the tetrad stage, the initial granular layer of the pro-ectexine first forms on the microspore plasma membrane. The tripar tite lamellae of the pro-endexine form under the pro-ectexine. The prosporo pollenin material is deposited on the pro-ectexine and pro-endexine at the free spore stage. The ectexine granule increases its volume and the endexin e lamellae thicken. The papilla protrudes during the tetrad stage. The tip of the papilla bends laterally where the exine is thinner, Exine construction in C. japonica is similar to that of Cunninghamia; howev er, the amount and size of the granular ectexine and lamellated endexine di ffer. The conspicuous papilla protrudes and bends during the tetrad period.