Polylepis - Reproduction

Reproduction

The pollen of Polylepis can be described as monads, isopolar, and more or less spheroidal to slightly oblate in shape. They have both an elongated and rounded aperture and the limits of the endoaperture (the inner openings of compound the aperture) are obscure. The elongated part of the aperture is completely covered by a pontoperculum.

The fruits of Polylepis are essentially achenes composed of the floral cup fused to the ovary. Fruits of all species are indehiscent (they do not open at maturity) and one seeded. The surface of the fruit of different species has ridges, knobs, spines or wings. There are no definite sites for the placement of these different types of protrusions that appear irregularly over the surface. The type of protrusion, wings verses spines, or knobs versus wings, is useful for distinguishing between species.

The flowers of all species of the genus are born on inflorescences. In most cases the inflorescences are long enough to hang like a pendant, but in the westernmost populations of P. tomentella and in at least one population of P. pepei, the inflorescence is so reduced that it remains almost hidden in the leaf axil. In the species with pendant inflorescences, the flowers are born regularly along the rachis or clustered toward the terminal end. The flowers themselves are reduced and have many features associated with wind pollination. These include: the absence of petals, green rather than colored sepals, an absence of scent or nectar, numerous anthers with long filaments, abundant, dry pollen, a large, spreading, fine fringed stigma, compounded pinnate leaves and the growth of trees in strands.