Dawsonia (plant) lamella – chains of small cells on the upper surface of the leaves analogous to the mesophyll cells of vascular plant leaves. They increase the surface area of cell walls available for CO uptake, while at the same time maintaining layers of moist air between lamellae, reducing water loss. Lamella margins have a surface wax layer which prevents water from flooding into the interlamellar spaces. Dawsonia (plant) Dawsonia is a genus of acrocarpous mosses. "Dawsonia", along with other members of the order Polytrichales, are taller than most mosses and have thicker leaves. Their sporophytes have conducting systems analogous to those
Germ layer Germ layer A germ layer is a primary layer of cells that form during embryogenesis. The three germ layers in vertebrates are particularly pronounced; however, all eumetazoans (animals more complex than the sponge) produce two or three primary germ layers. Some animals, like cnidarians, produce two germ layers (the ectoderm and endoderm) making them diploblastic. Other animals such as chordates produce a third layer (the mesoderm), between these two layers. making them triploblastic. Germ layers eventually give rise to all of an animal’s tissues and organs through the process of organogenesis. Caspar Friedrich Wolff observed organization of the early embryo