As epithelial makes the outer covering of all the organs and skin is also made of epithelial...so to be sure that it does not get depleted or destroyed due to friction and other external cause ...it should be highly generative !
Both gymnosperms and angiosperms have vascular tissue that is specialized for transport of minerals, water, and organic compounds. Also, both gymnosperms and angiosperms have seeds. The only difference is that angiosperms have seeds hidden in the ovary while gymnosperms have seed on the surface of the scales of the cones.
Mutalism, commensalism, and parasitism