Key Concepts: In dicotyledonous leaves there are two types of mesophyll cells, palisade mesophyll and spongy mesophyll. Palisade mesophyll cells form a layer beneath the upper epidermis whereas spongy mesophyll cells are internal to the lower epidermis. major role of leaf mesophyll cells is to contain large populations of chloroplasts, which carry out photosynthetic carbon assimilation facilitating plant growth. Keywords: palisade mesophyll; spongy mesophyll; airspace; bundle sheath; chloroplast. Figure 1.
A ridge or mountain ridge is a geological feature consisting of a chain of mountains or hills that form a continuous elevated crest for some distance. Ridges are usually termed hills or mountains as well, depending on size.
Ridge Beam vs. Ridge Board. A Ridge Beam and a Ridge Board are both located at the ridge but they serve very different purposes for very different applications. A ridge beam is a structural member used to support the ends of the rafters at the ridge, transferring it's loads to posts or gable end walls. Ridge beams are required by code if the roof slope is less than 3 in 12 (IRC section R802.3).