BIOL 1130 Lecture Notes - Cutin, Suberin, Cork Cambium
27 Sep 2013
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Will have parenchyma cells, tracheids, vessels, fibers. Tracheids have overlapping pits vs. vessels which are attached end to end. Ray cells transport h2o + nutrients laterally when there is secondary growth. Transport cells are termed sieve tube members. Are alive at maturity cytoplasm extends through the sieve plate to the cells. Sieve tube members lack organelles like mitochondria, dictyosomes, Joined together where there is a sieve plate ribosomes, vacuole. Have companion cells associated with the sieve tube members which supply needed substances: ex. Covered by a cuticle which has a waxy " covering termed cutin protect the plants, waterproof, helps stop insects and small bugs and herbicides. Plants must have gaseous exchange with the atmosphere. Small opening stomata formed by opening & closing of guard cells. Replacement tissue for the epidermis in stems that have secondary growth. Have a waterproof substance secreted while still alive suberin. Lenticels openings in the bark allow some gaseous exchange.
