General Biology - Plants Have Organs, Too

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Vegetative organs

Vegetative organs

• Organs that allow the plant to live and grow

• Includes the root stems, and leaves

Root

Anchors the plant to the soil for support and absorbs water and minerals from the soil

Stem

• The main axis of the plant together with its branches

• Functions as a support and for the transport of water and nutrients absorbed by the roots to the leaves

• Distributes the products of photosynthesis to the other plant parts

Leaves

• Are responsible for the manufacture of food by photosynthesis

Meristematic & Permanent

Two types of tissues in vascular plants

Surface (dermal), Fundamental (ground) and Vascular

Basic Tissue System

Meristematic Tissues

• Allow growth

• Embryonic tissue that made up meristems

Meristems

Part of the plant where growth is fastest

Apical Meristems

Found in the tip of the stems or roots that allow these organs to grow longer

Lateral Meristems

• Called as secondary meristems or lateral buds or axillary buds

• Found on the nodes of stems and are involved in the formation of branches

Cambium

A ring of meristematic tissues found inside a mature stem, which allows growth in diameter or increase in the thickness of stem or roots

Vascular Cambium

Produces new layers of vascular tissues

Cork Cambium

Produce new layers of surface tissues called cork

Surface Tissues

• Protect

• Dermal tissues

• Cover and protect the surface of the different plant organs

• The epidermis of a leaf is an example of _________ where the outer cell is covered with a layer of cuticle that is made up of a substance called cutin

• Cork is another example of ______________ that covers the outer surface of the bark of woody stems and roots

Cutin

A waxy substance that prevents water loss

Cuticle

Protects against bacteria and other organisms that may cause harm to the plant

Epidermis

Also found in the outer layer of leaves, stems, roots, flowers, and even seeds

Root Hairs

Are slender projections found in the epidermal cell of roots, which enables a cell’s modification to increase the surface area of the root for absorption

Guard Cells

Are modified epidermal cells found on leaves that function to open or close the stomata

Stomata

The leaf opening for gas exchange

Fundamental Tissues

• Fill

• Ground tissues

• Form the main bulk of plants

• They fill most of the spaces in any plant organ

Parenchyma Cells

• Best represent a typical plant cell

• Large, thin-walled, and usually have a large central vacuole

• Usually contain plastids

• Food storage

• Capable of cell division and could give rise to more specialized cells, such as when roots develop from step cutting placed in water

Collenchyma Cells

• Functions mainly as support

• They have thicker cell wall

Sclerenchyma Cells

• Have a thick secondary cell wall in addition to the primary cell wall

• The secondary cell wall is impregnated with lignin, an organic substance that makes the cell wall tough and hard

• Nonliving and function as a support to the mature parts of the plant

Fibers

Are long and slender

Sclereids

Irregular in shape

Vascular Tissues

• Transport

• Complex conducting tissues that extend from the roots to the leaves of plants

Xylem

• Transports water and minerals from roots to leaves via the stem

• Contains parenchyma cells that store substances

Tracheids

Elongated, hallow, and nonliving cells with tapered ends

Vessel Elements

Also hallow and nonliving, but are larger and without end walls

Phloem

• Transports organic nutrients in both directions along the length of the plant

• Contains living conducting cells called sieve tube members

Sieve Tube Members

Are elongated cells with few organelles and no nucleus

Sieve Plates

End walls of the sieve tube members

Companion Cells

Are believed to control the transport activities of the sieve tube cells

Leaves

• Are the chief organs of plants for photosynthesis

• Function in asexual reproduction

Deciduous Plants

Change the colors of their leaves with the changing of the season or lose them with the onset of the winter

Stomata

Pores that close or open to let essential gases enter and leave the leaf

Stoma

Greek word that means mouth

Stem

Is an above ground structure that supports the leaves, transports water and important nutrients between roots and leaves, and produces new tissue for growth

Terminal Bud

• Apical bud

• Produces new leaves and other tissues during primary growth

Lateral Bud

• Axillary bud

• Where a leaf connects with the stem

Node

Where the leaf or leaves attach to the stem

Internode

Region in between nodes

Herbaceous Stem

Has no relation to cambium growth, that is why it is soft

Woody Stem

Hard and rigid

Roots

• Enables a plant to anchor itself in the soil while absorbing water and minerals to the rest of its body

• Have a slimy surface and cylindrical shape that allows the plant to penetrate the soil as they grow in size and also allow water to be absorbed from all directions

• Also functions as an important storage for food produced by plants

Root Cap

• Tip of the root

• Protects the plant from rock injury that may damage the roots as it grows

Adventitious Roots

• Arise from an organ other than the roots, such as the stem or the leaf

• Can be modified for aerial support known as prop roots