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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 ?
Pollen exine - the sporopollenin enigma and the physics of pattern.
Microsporogenesis and exine substructure in Uraria crinita (Fabaceae).
have pollen subprolate, large size, tricolporate, exine Mutisia type, microechinate (see also Cabrera, 1965; Skvarla & Turner, 1966; Heusser, 1971; Parra & Marticorena, 1972; Skvarla et al.
Pollen subprolate to spheroidal, large size, tricolporate, exine Mutisia type, slightly microechinate (see also Southworth, 1983; Lin et al.
Exine Mutisia type, microechinate, 4-5 [micro]m thick, slightly slender at the poles.
The exine is largely unomamented externally (psilate to scabrate) and has two layers that are visible using light microscopy (LM).
4 mm, stamens exceeding the petals by a fraction of the anthers, filaments subcomplanate, not at all delated toward the apex, pale yellow, adnate to the petals for 3-4 mm, anthers linear, 7-10 mm long, base sagittate and apex obtuse, fixed near the base, pollen oblong-elliptic, sulcate, exine reticulate, lumina subrounded, muri narrowed, style exceeding the petals for ca.
Given the abundant pollen present in specimens of Chitaleypushpam, an SEM study detailing exine sculpture and pore and colpi characters could help clarify its relationships.
7 mm long, sublinear, base acute and apex acute and apiculate, dorsifixed at the middle, the antesepalous ones slightly exceeding the antepetalous ones; pollen biporate, broadly oblong-elliptic, pores large, exine reticulate, lumina polygonal, muri narrowed; stigma conduplicate-spiral, ellipsoid, white, lobes with densely crenulate-papillose margins; ovary clavate, trigonous, white, glabrous, ca.
The pollen of modern Trapa is distinctive, being tricolpate, triangular in polar view with protruding, enlarged, domed apertures and a granular exine that is crossed by three frilled meridional ridges (crests) that unite and enlarge at the poles (Patel et al.
In 1970, Hesslop and Harisson have assigned the situation of allergen proteins, in exine of pollen grains especially near to growing holes.