plant organs system

Plant Organs System

Roots & StemLeaf

Flower & Fruits

The plant body consists of two basic parts: the shoot system and the root system.

• Shoot System: includes organs such as leaves, buds, stems, flowers, and fruits and usually it develops above ground.– The functions of the shoot system includes:• Photosynthesis• Reproduction• Storage• Transport• Hormone production

• Root System: includes roots as well as modified stem structures such as tubers and rhizomes and usually it develops underground.– The functions of the root system includes:• Anchorage• Absorption• Storage• Transport• Production of certain hormones

• ROOTS & STEM• LEAF

• FLOWER & FRUITS

Roots

• Root– is the organ of a plant that typically lies below the

surface of the soil.– a root can also be aerial (growing above the

ground) or aerating (growing up above the ground or especially above water).

– PARTS OF A ROOT.

PARTS OF A ROOT

• Root tip Cambium– Meristem Water Uptake– root cap Mineral Uptake

• The Region of Elongation Gas Exchange• The Region of Differentiation– Epidermis– Cortex– Endodermis– Stele• Pericycle• Xylem • Phloem

PARTS OF A ROOT

• Root Tip– Meristem- a region of rapid mitosis, which

produces the new cells for root growth.

PARTS OF A ROOT

• Root Cap– a sheath of cells that protects the meristem from

abrasion and damage as the root tip grows through the soil.

PARTS OF A ROOT

• The Region of Elongation– Here the cells produced by mitosis undergo a

period of elongation in the direction of the axis of the root. It is at this time that they are sensitive to gravity and respond with gravitropism.

PARTS OF A ROOT

• The Region of Differentiation– Here develop the differentiated tissues of the

root.

PARTS OF A ROOT

• Epidermis– A single layer of flattened cells at the surface. When first formed,

epidermal cells have extensions - the root hairs - which greatly increase the surface area available for the uptake of water from the soil. The photo below shows the root hairs in the region of differentiation of a germinating radish seed.

PARTS OF A ROOT

• Cortex– A band of parenchyma cells that develops beneath

the epidermis. It stores food. Its inner surface is bounded by a single layer of cells, the

• Endodermis.

PARTS OF A ROOT

• Stele– Pericycle• the outer boundary of the stele. Secondary

roots branch from it.

PARTS OF A ROOT

• Xylem– arranged in bundles in a spoke like fashion.– caries water and disolved nutrients from the roots

throughout the plant.

PARTS OF A ROOT

• Phloem – alternates with xylem.– carries/ distributes the products of photosynthesis

(mainly from the leaves) to the rest of the plants.

PARTS OF A ROOT

• Cambium – In older parts of the root, another meristem forms

between the xylem and phloem. Mitosis in the cambium produces new "secondary xylem" to the inside and secondary phloem to the outside.

PARTS OF A ROOT

• Water Uptake– Water enters the root through the root hairs. These

extensions of epidermal cells have sickly walls and adhere tightly to soil particles with their film of moisture.

PARTS OF A ROOT

• Mineral Uptake– One might have expected that minerals would enter the

root dissolved in water. But, in fact, minerals enter separately:Even when no water is being absorbed, minerals enter freely.

– Minerals can enter against their concentration gradient; that is, by active transport.

– Anything that interferes with the metabolism of root cells interferes with mineral absorption.

PARTS OF A ROOT

• Gas Exchange– The older parts of roots are sheathed in layers of dead cork

cells impregnated with a waxy, waterproof (and airproof) substance called suberin. This sheath reduces water loss but is as impervious to oxygen and carbon dioxide as it is to water.

– However, the cork is perforated by nonsuberized pores called lenticels. These permit the exchange of oxygen and carbon dioxide between the air and the living cells beneath.

Stem

• Stem– A stem is one of two main structural axes of a vascular

plant.– The stem is normally divided into nodes and internodes,

the nodes hold buds which grow into one or more leaves, inflorescence (flowers), conifer cones, roots, other stems etc.

• PARTS OF STEM.

PARTS OF STEMLeaf scar - is the mark left on a stem after a leaf falls.

Terminal bud - is the main area of growth in most plants.

Lenticel - it function as a pore, providing a medium for the direct exchange og gases between the internal tissues and atmosphere.

Flower bud – have not yet bloomed into a full-size flower.

Growth rings - also referred to as tree rings or annual rings, can be seen in a horizontal cross section cut through the trunk of a tree.

Leaf

• Leaf– A leaf is an organ of a vascular plant, as defined

in botanical terms, and in particular in plant morphology.– Typically a leaf is a thin, flattened organ borne above

ground and specialized for photosynthesis, but many types of leaves are adapted in ways almost unrecognisable in those terms: some are not flat (for example many succulent leaves and conifers), some are not above ground (such as bulb scales), and some are without major photosynthetic function (consider for example cataphylls, spines, and cotyledons).

– PARTS OF THE LEAF.

Chloroplasts

• A chloroplast is a structure in plants that is where photosynthesis happens.

Flower

• Flower– A flower is the part of the plant that makes the

seeds.– A flower, sometimes known as a bloom or

blossom, is the reproductive structure found in flowering plants.

– PARTS OF A FLOWER.

Parts of Flower

• Pollen• Anther• Filament• Stamen• Stigma• Style• Ovary• Pistil• Seeds• Sepal• Petals• Stem

Parts of Flower

• Pollen– sperm of the plant.– is a fine to coarse powder containing the micro

gametophytes of seed plants, which produce the male gametes (sperm cells).

Parts of Flower

• Anther– contains the pollen.

Parts of Flower

• Filament– are a series of chain like cells.– stalk on which anther is attached, longer in wind pollinated

plants.

Parts of Flower

• Stamen– male part of plant, parts where pollen anther and

filament are combined.

Parts of Flower

• Stigma– sticky part to which pollen attaches.

Parts of Flower

• Style– simply, a tube through which sperm travel to

seeds.

Parts of Flower

• Ovary– contains the seeds, later to become the fruit of

the plant.

Parts of Flower

• Pistil– female part of the plant, parts where Stigma,

Style and Ovary are combined.

Parts of Flower

• Seeds– future plants, contained in the ovary.

Parts of Flower

• Sepal– tiny leaf-like structures that protect the flower as a

bud.

Parts of Flower

• Petals– brightly colored, used to attract pollinators.

Parts of Flower

• Stem– supports the flower.

Fruits

• Fruits– is a part of a flowering plant that derives from

specific tissues of the flower, one or more ovaries, and in some cases accessory tissues.