classnotes15 - Plant diversity Preliminary note: We are...

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Preliminary note: We are just doing some highlights here, and we won't be covering fungi since you did that in 103 (they're not plants in any case). I. Origin of Plants: - evolved from green algae. Some of these can get quite large and look remarkably like modern plants (e.g., giant kelp off the west coast). - closest living relative to plants is probably something called a Coleocheate. It likes shorelines surrounding lakes. - Plants needed to adapt to dry land. Following the outline in the text, we'll consider four major adaptations for this: 1) Need to obtain resources from water and air. The basic structure of a plant includes shoots and roots (more later). [OVERHEAD, fig. 31.3, p. 624] Roots are designed to absorb minerals and nutrients from the soil. They also anchor the plant. Shoots are designed to photosynthesize and pick up carbon dioxide from the air (and get rid of oxygen). Both have specialized areas that help the plant grow (more later). Connecting everything in a plant is vascular tissue. This is composed of two parts: xylem: moves water through the plant (generally upwards). phloem: moves nutrients around the plant. 2) Support. To get more than a few inches tall, plants need specialized supporting cells with lignin deposits (lignin = the “woody” part of a plant). These cells may be separate or be part of the xylem. 3) Water retention. Plants need special structures to prevent water loss. A water resistant cuticle (often waxy) serves many plants as a barrier. Water loss can be controlled by opening or closing special openings in leaves (and sometimes other structures) that regulate water loss. 4) Reproduction.
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classnotes15 - Plant diversity Preliminary note: We are...

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