BIOL 115 Lecture Notes - Lecture 17: Cactus, Dicotyledon, Root System
25 Jun 2016
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Lecture 7: plant body structure and nutrition. Stem modifications: modified to store food, eg potatoe. Runners for horizontal stems cacti modified to store water, no leaves (= spines), become green and carry out photosynthesis. Root modifications: carrots, etc, fibrous roots, prop roots on corn, can grow new ones above water level to take in oxygen. In a cross-section of the stem, vascular bundles are arranged differently in dicots (in a ring) and monocots (scattered). Internal structure of the primary root: there is a large difference in the arrangement of the vascular system in a eudicot and a monocot primary root. Leaves: simple leaves those with a single blade, with an axillary bud at the axil of that leaf, complex leaves many leaflets arranged along a central axis. Also can have further division of the axis resulting in a doubly compound leaf: has cells for photosynthesis, palisade mesophyll cells, bundle sheath cells.
