Bio Chapter 36

when plants are able to grow continuously in any direction in response to favorable conditions

• the "generic" plant
• a seed plant that lacks wood and has a relatively short-lived stem

• roots show a great deal of this, meaning that they are plastic/changeable, depending on environmental conditions
• genetically identical individuals will have very different-looking root systems if they are growing in different environments

• compact forms that form in species that have extremely reduced internodes
• dandelions and cabbages are examples

• stems are enlarged into water-storage organs
• its leaves are modified into protective structures called spines

• runs over the soil surface, produces roots and leaves at each node
• 

• stems that grow horizontally instead of vertically.
• stolons grow aboveground, while rhizomes spread belowground.
• store starch
• 

• underground, swollen ends of thizomes that function as carbohydrate-storage organs
• the eyes of a potato are nodes in the stem where new branches may arise

modified stems that help protect the plant from attacks by large herbivores

• gives rise to the dermal tissue system.
• this is also called the epidermis

forms the ground tissue system, which makes up the bulk of the plant body and is responsible for photosynthesis and storage

forms the vascular tissue system, which provides support and transports water and nutrients between the root system and shoot system.

• closest behind the root cap
• contains the apical meristem, where cells are actively dividing

• middle position behind the root cap
• made up of cells that are recently derived from primary meristematic tissues
• actively increases in length

• farthest away root cap
• where older cells complete their differentiation into dermal, vascular, and ground tissues

ground tissue inside the vascular bundles

ground tissue outside the vascular bundles

• epidermal cells secrete the cuticle, a waxy layer on the outside of the plant
• the cuticlereduces the amount of water that is lost by evaporation from the interior of the plant.
• also prevents bacteria and pathogens from entering plant

allow gases to get through the cuticle by diffusion

• are the most abundant and versatile plant cells
• primary site of photosynthesis
• also store starch deposits
• most are totipotent

• function mainly in support
• even when mature, their cell walls retain the ability to stretch and elongate
• "strings" of celery include many strands of collenchyma cells

• support cells that produce a thick secondary cell wall in addition to the thin primary cell wall found in all cells
• secondary cell wall contains the rigid compound lignin.
• support after active growth has ended
• dead at maturity

extremely elongated, may be used in manufacture of paper, hemp, or linen

• short, have variable shapes
• function in protection
• touch coats of seeds and the thick shells of nuts

water and dissolved ions from the roots travel up to shoots

sugar, amino acids, chemical signals, etc. throughout the whole plant body

• water-conducting cells inside the xylem
• dead at maturity
• present in angiosperms

• in phloem, type of parenchyma
• long, thin cells that have perforated ends called sieve plants
• responsible for transporting sugar and other nutrients
• no organelles

• in phloem, type of parenchyma
• contain all of the organelles normally found in a plant cell

• to extend the reach of the root and shoot systems
• increase the plant's ability to absorb light and acquire CO2, H2O, and ions

• to increase the amount of conducting tissue available and provide the structural support required for extensive primary growth
• increases width
• produces wood

• also called a secondary meristem or cambium
• form cylinders that run the length of a root or stem
• divide in a way that increases the width of roots and shoots

• secondary phloem and xylem are only found in gymnosperms and some angiosperms
• secondary phloem: sugar transport
• secondary xylem: water transport and structural support, forming wood
• the parenchyma cells radiate laterally across the xylem and form rays

• corl cells to the outside
• phelloderm to the inside
• altogether make up the periderm
• allows continued protection of the woody stem when it increases in width
• also protects the shoot system from fire damage

• inner xylem region of a tree
• provides structural support but no longer transports water
• darker colored

• outer xylem region of a tree
• includes active water-conducting xylem tissue

• As the growing season ends, conditions dry out or become cooler, so the secondary xylem cells that are produced at this time are smaller, thicker walled, and darker in appearance.
• this period of no growth is called dormancy