Ch 23 Roots, Stems, and Leaves

Apical Dominance

central stem of the plant is dominant over (i.e., grows more strongly than) other side stems

apical meristem

produces growth of new cells, top of the plant (tissue that makes plants **grow longer by adding new cells)**

auxins

regulatory substances produced by tips of growing plants that stimulate cell elongation

capillary action

tendency of water to rise in a thin tube

Casparian strip

cell walls meeting and forming a special waterproof zone

cortex

ground tissue in roots that surrounds vascular tissue

epidermis

dermal tissue in young plants consisting of a single layer of cells

ethylene

colorless, flavorless gas that inhibits growth, promotes leaf fall and ripening

fibrous root

branched roots that grow from the base of a stem

gibberellins

plant hormone that regulate developmental processes, such as growing, flowering, etc.

gravitropism

ability of plants to grow in response to gravity, shoots going up, roots going down

ground tissue

makes up the inside of non-woody plants (roots, stems, leaves)

guard cells

highly specialized cells that surround the stomata and control their opening and closing

homeostasis

maintain stability, adjust internally in order to maintain

hormones

chemical changes that affect growth, activity, and development of cells and tissues

meristems

regions of unspecialized cells in which mitosis produces new cells ready for differentiation

mesophyll

area between leaf veins filled with specialized ground tissue

photoperiodism

response of a living organism in changes of day and night

phototropism

ability of plants to bend or grow towards light

primary growth

growth of new cells produced by apical meristem

secondary growth

increase in thickness of stems and roots

sieve tube elements

end walls that have small holes in which nutrients moves through in a water stream

stomata

small openings in the epidermis that allow carbon dioxide, oxygen, water to diffuse out

taproot

large, primary root that smaller roots branch off of

target cells

cells affected by a particular hormone

thigmatropism

movement or change in a plant’s growth orientation in response to touch

tracheid

conductive cell in xylem

transpiration

loss of water through pores

tropisms

turning of one organism is response to an external stimulus

vascular bundles

clusters of xylem and phloem tissue

vascular cylinder

transports water and minerals