The decay-resistant outer coating of a pollen grain or spore. It typically bears a highly characteristic surface pattern that is used in palynology.
- ‘Short elongated elements occur on the orbicule wall, similar to those present on the pollen exine.’
- ‘The final activity of these cells is to deposit their remaining cell contents onto the developing pollen exine, with the only remaining identifiable organelles at this stage being the mitochondria.’
- ‘Orbicules may be attached to the exine of the pollen grains.’
- ‘This study concentrates on these parameters using purified exines (sporopollenin capsules) prepared from pine pollen, which consist of a central capsule and two lateral sacci.’
- ‘A few grains were seen which had shed the exine and released a circular microgametophyte, although the actual process was not observed.’
Late 19th century: perhaps from ex- out + Greek is, in- fiber.