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(also exosporium), in seed plants, the outer layer of the wall of pollen grains (microspores). In many plants the outside of the exine has nodules or reticular enlargements, which form specific patterns characteristic of a particular species and are there fore often used to identify the species to which a pollen grain belongs.

References in periodicals archive ?
Description: Miospore, trilete, amb triangular, lete distinct, raised, arms of lete extending up to angles, labra distinct, massive, raised, exine up to 2 m thick, infra punctate, exhibiting occasional folding along the margin of the contact area, exoexinal layer generally present
The endexine is the inner part of the exine, is located above the foot layer and has a different electron density than the foot layer.
Description: Miospore, trilete, amb circular to sub-circular to broadly triangular, Y-mark distinct, reaching up to the radius, exine punctate to vermiculate, up to 2m thick.
Olive pollen ultrastructure: characterization of exine pattern through Image Analysis-Scanning Electron Microscope (IA-SEM).
One of the most prominent and interesting features of malvaceous pollen is the echinations or prolongations of the exine into definite spines (El Naggar 2003).
Description: Pollen grain, monosaccate, amb of corpus circular to sub circular conforming perfectly to the overall amb, exine of corpus thin, trilete mark absent with numerous plications.
Endoapertures (Pori) Circular or almost square in outline, Exine striate-perforate; striate (ridge-and-valley-pattern) crowded, usually parallels together or colpus, 0/27-0/33 um in width and perforations 0/07-0/1 [micro]m in length (fig 4)
5 mm long, base obtuse, apex obtuse and minutely apiculate, compressed laterally, dorsifixed at 1/3 of their length above the base, pollen sulcate, ellipsoid, exine micro-insulate- reticulate, muri thickened, stigma simple-erect, ca.
Description: Pollen grain, polyplicate, overall amb elongate oval, extremities sharply to broadly rounded, exine polyplicate with 3-5 or more massive folds on the proximal face running parallel to the long axis of grain and associated with fold is a narrow linear longitudinal cleft in the exoexine detectable under oil immersion.
The exine is largely unomamented externally (psilate to scabrate) and has two layers that are visible using light microscopy (LM).
Exine (Ex) and Intine (In) are formed in this stage (fig 2 E) and tapetum in this plant is plasmodial type.