Pollination cones (female), but some species are monoecious and others dioecious. A pollen cone contains hundreds of microsporangia carried on (or borne on) reproductive structures called sporophylls. Spore mother cells in the microsporangia divide by meiosis to form haploid microspores that develop further by two mitotic divisions into immature male gametophytes (pollen grains). The four resulting cells consist of a large tube cell that forms the pollen tube, a generative cell that will produce two sperm by mitosis, and two prothallial cells that degenerate. These cells comprise a very reduced microgametophyte, that is contained within the resistant wall of the pollen
Xylan (coating) Xylan (coating) Xylan is a fluoropolymer-based industrial coating. Generally, it is applied in a thin film to the target material. Xylan is generally used to reduce friction, improve wear resistance, and for non-stick applications. Additionally, it can be used to protect a metal from corrosion. The most commonly known application is in non-stick cookware but Xylan coatings have also been used extensively in the automotive industry and for corrosion protection in the oil and gas industry. Xylan is the umbrella trademark for most of the Whitford Corporation fluoropolymer coatings line. Xylan is made of low friction, wear resistant composites of