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Unformatted text preview: Chapter 35 Plant Structure, Growth, and Development Concept 35.1: The plant body has a hierarchy of organs, tissues, and cells Describe and compare the three basic organs of vascular plants. o Root : a multicellular organ that anchors the plant in the soil, absorbs minerals and water, and often stores carbohydrates o Stem : a vascular plant organ consisting of an alternating system of nodes and internodes that support the leaves and reproductive structures o Leaf : the main photosynthetic organ of a vascular plant; usually consist of a flattened blade, stalk, and petiole List the basic functions of roots. Describe root hairs. o Basic Functions: Anchors a vascular plant in the soil Absorbs minerals & water Often stores carbohydrates o Taproot: a main vertical root that develops from an embryonic root and gives rise to lateral (branch) roots o Lateral (branch) Roots: a root that arises from the pericycle of an established root o Adventitious : a plant organ the grows in an unusual location, such as roots arising from stems or leaves o Eudicots & Gymnosperm: Have a taproot system consisting of one main vertical root (taproot) that develops from embryonic root. The taproot gives rise to lateral (branch) roots In many angiosperms the taproot stores sugar and starches that the plant will consume during flowering period. This is why root crops such as carrots, turnips, and beets are harvested before they flower. Taproot systems generally penetrate deeply Well adapted to deep soils where groundwater is not close to the surface o Monocots & Seedless Vascular Plants: Embryonic root dies and does not give rise to a main root Many small roots grow from stem; Such roots are said to be adventitious, a term describing a plant organ the grows in an unusual location, such as roots arising from stems or leaves Each small root forms its own lateral roots resulting in a fibrous root system Fibrous root systems usually do not penetrate deeply and are best adapted to shallow soils or regions where rainfall is light and does not moisten the soil much below the surface layer (ex. grasses) o Root Hairs: a tiny extension of a root epidermal cell, growing just behind the root tip and increasing surface area for absorption of water & minerals A root hair is a thin tubular extension of a root epidermal cell Despite their great surface area root hairs do not provide much support in anchorage; their main function is absorption Describe the basic structure of plant stems. o Node: the point along the stem of a plant at which leaves are attached o Internode: A segment of a plant stem between the points where leaves are attached o Axillary Bud: a structure that has the potential to form a lateral shoot, or branch....
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This note was uploaded on 04/03/2012 for the course BIOL 1202 taught by Professor Gregg during the Spring '08 term at LSU.
- Spring '08