Chapter 4 - Tissues

Permanent regions of growth, areas of cell division

• Meristematic tissue • Area of primary growth (in length). • At tips of roots and shoots, also at base of leaves.

• Meristematic tissue • Area of secondary growth, produces tissues that increase the girth of roots and stems. • Not in every plant (like impatiens).

• One type of lateral meristem. Not in grasses. • Function: Transport and support; make trees bigger in width (rings in trunk). Also just called “cambium”. • Extends throughout the plant, roots to stems

• One type of lateral meristem. Not in grasses. • Relates to bark, builds bark cells. Runs the length of the plant, roots to stems. • Not in herbacious plants.

• A type of simple tissue • The most abundant tissue, in every plant part: leaves, stems, fruits, roots, etc. • Loosely packed in the cell, lots of space between cells for movement of materials like H2O, CO2, etc. • Function: synthesize materials, some transport. • Thin cell walls • Living • Live a long time; in some cactus plants, may live to over 100 years old.

• A type of parenchyma tissue, containing chlorophyll, for photosynthesis.

• A type of simple tissue • Function: structure and strength; enables flexibility in such like palm trees to bend in the wind • Thick cell walls, especially at corners (extra primary wall), thinner along sides; tightly packed together; ribs in celery, center rib in leaves are examples • Living • Can live a long time

• A type of sclenenchyma • “Stone cells”; thick cell walls, can be brittle; nut shells, peach pits, and gritty part of immature pears (protection from being eaten too soon) • Dead

• A type of complex tissue • Produced mostly by the vascular cambium (as opposed to the apical meristem) • Made of: 1) vessel cells, 2) tracheids, 3) parenchyma, and 4) fibers (and 5) ray cells, a specialized type of parenchyma for lateral conduction of water and nutrients • Function: transports water and nutrients from the roots to the above-ground parts of the plant (and sugars in the spring); some support - 90% of tree trunks are xylem-strength

• A type of simple tissue • Two kinds: fiber and sclereids • Function: support and strength • Dead

• A type of sclerenchyma • Long, tubular and pointed; thick cell walls • Function: strength; source of twine, hemp, jute; keeps plants from breaking • Dead

• Part of xylem tissue • Tubular, stackable, and open-ended; largest-diameter transport cell; composed of vessel cells (elements) • Function: transport water and nutrients; have some pores on sides to allow water to seep out along the way • Dead cells

• Part of xylem tissue • Have thick secondary walls, tapered at each end. Where ends overlap with other tracheids, there are “pits” in cell wall where no secondary wall has formed, allowing the passage of water between them. Smaller of the 2 kinds of vessels • Dead cells

• A type of complex tissue • Made of 1) Sieve tube cells, 2) Companion cells, 3) Parenchyma, and 4) fibers (and 5) ray cells) • Function: transports sugars and sometimes hormones from the above-ground plant parts to the roots and other parts of the plant

• Part of phloem tissue • Laid end-to-end like vessel elements. Hollow like vessels, but ends not open; have open pores in sieve plates that allow cytoplasm to flow from cell to cell. Have no nuclei. • Function: Vessels to transport the sugars produced by the plant • Living cells, but can’t regulate the transport (performed by the companion cells)

• Part of phloem tissue • Narrower, smaller than sieve tube cells, tapered. • Function: Regulates the materials moving through the sieve tubes • Living

• Outer layer of cells of all young plant organs, protective layer covering all plant organs • Usually once cell thick, except in plants that produce aerial roots • Made primarily of parenchyma cells, plus some other specialized cells • Function: protection from water loss, fungi, insects; transport; produces (excretes) cutin for cuticle layer

• Waxy substance on outside surface of plants * Excreted by the epidermis

• Layer of wax (cutin) on the outside surface of leaves. * Function: limits water evaporation through cell walls; resists bacteria and disease organisms

• Pores in the epidermis, composed of 2 guard cells which regulate it • Function: Transport, allows passage of CO2 and O2 gases into and out of the leaves. • Usually on the underside of leaves (to limit water loss through them), but can be on top or both (like corn leaves). • When closed to drought, limits photosynthesis (last year’s fruits were smaller but sugars were more concentrated

A

• 2 cells that regulate the stomates, opening and closing them • Contain chloroplasts

• Modified epidermal cells that excrete protective substances.