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.
Ridges drop away steeply on one or both sides, which makes them exciting places to walk. A ridge is a line of high ground, with the land dropping away on either side. Ridges are common between two hilltops, such as between Kanturk and Scarr. The low point on a ridge is called a 'col' or 'saddle'.