Plants

Plant Identification

• Many things are taken into consideration when trying to identify a plant.

• Roots, stems, leaves and flowers will help in the identification process.

Plant Identification

• You have two main categories of plants.–Monocots – grasses, grain crops, lilies,

gladiolas, and palm trees

Plant Identification

–Dicots - most of the other plants such as the shrubs, trees, and flowers.

Types of Roots

• Tap Root–Have a main central root and

may have some lateral branching–E.g. Carrots

Types of Roots

• Fibrous–Have many roots of equal size and a lot

of lateral branching–Fibrous roots are generally much more

diffuse and closer to the surface

Types of Roots

• Nitrogen fixing roots - members of the Leguminosae family (alfalfa, peas and clover) have a bacteria that infects their roots and forms nodules. The bacteria are able to fix atmospheric nitrogen, to a form, that the plant can use.

Dicot Seed

Monocot Seed

Mature Structure of Woody vs Herbaceous Stems

• Herbaceous stems–Lack secondary growth - because

plants only live one year/growing season (annuals)

Mature Structure of Woody vs Herbaceous Stems

• Woody stems–Plants living and growing over multiple

seasons have secondary growth (xylem, phloem) increasing diameter of the stems

Parts of a Dicot Leaf

• Leaf blade – expanded, usually flat portion of a leaf – contains chloroplasts

• Petiole – connects the blade of a leaf to a stem or branch – holds leaf up for better air flow and to catch the light

Parts of a Dicot Leaf

• Veins – threads of vascular tissue (xylem & phloem)

• Node – place on a stem where leaves or branches normally originate

• Stem – used for support of leaf

Leaf Blade

Petiole

Veins

Where leaf would be attached to the branch or stem at the node.

Dicot Leaf

Parts of a Monocot Leaf

• Node – where leaf arises or originates from

• Blade – leaf blade – flat upper portion of leaf

• Stem – used for support of leaf, inflorescence, and seed heads

Parts of a Monocot Leaf

• Sheath – part of leaf that holds leaf to stem – encases stem

• Ligule – membrane-like tissue extending up from the sheath (on inside) – keeps dirt and moisture out – clear membrane on leaf where attaches to stem

Sheath

Blade

Node

Collar

Auricle

Ligule

Stem

Monocot Leaf

Differences Between Monocot and Dicot Leaves

• Monocots – blade like leaf blade – wrap around the stem – no petiole – have main vascular bundles running parallel along length of leaf

• Dicots – Have both a leaf blade and a petiole – single midrib (Vascular bundles) with branches

Two Types of Leaves

• Simple leaves – composed of a single leaf and a petiole

Simple Leaf

Blade

Petiole

Two Types of Leaves

• Compound leaves – are composed of a blade that includes several leaflets and a petiole – also contain a rachis (connects leaflets to the petiole) – two types:

Two Types of Leaves

–Palmately Compound – (chestnut) – the lobes or divisions come together and are attached at one place at the base

Palmately Compound Leaf

Leaf Blade

Petiole

Two Types of Leaves

–Pinnately Compound – compound leaf with the leaflets on two opposite sides, but off of one node – ex: ferns, ash, hickory

Pinnately Compound Leaf

Leaf Blade

Leaflets

Petiole

Leaf Arrangement

• Monocots – have only one type of arrangement – leaf comes off of a node – ex: grasses and grain crops

Leaf Arrangement

Dicots – flowering plantsAlternate – one leaf per nodeOpposite – two leaves per nodeWhorled – three or more leaves per

node

Leaf Arrangements

Whorl – look like helicopter blades – ex: Bedstraw

Alternate – one on each side of the stem, are not opposite of each other but every other one

Opposite – one on each side of the stem and opposite of each other

Arrangement of Veins

• Four types of vein arrangements:–Parallel veins – veins are small

and run more or less parallel – most are long and narrow – ex: Buckhorn Plantain, grasses and Iris – mostly monocots

Arrangement of Veins

–Netted veins – are large and small – the small ones connecting to each other to form a net – mostly dicots

Arrangement of Veins

–Pinnately veined – with one larger midvein and smaller veins coming off along its length – mostly dicots

Arrangement of Veins

–Palmately veined- with two or more large veins arising at or near the base of the leaf blade (palm) – leaves are usually broad or fat – mostly dicots

Parallel Veins

Netted Veins

Pinnately Veined

Palmately Veined

Flowers

–Dicots –have sepals and/or petals in multiples of four or five–Monocots – have sepals in multiples of

threes

Angiosperms – flowering plants.Gymnosperms – cone bearing plants.

Parts of a Flower

Petals

Stamens (anther & filaments)

Pistil (stigma,style & ovaries)

Sepals

Pedicel

Sepals

Receptacle

Pedicel

Parts of a Flower

Types of Monocots and Dicots

Vascular Bundle of Monocots

• In monocots, the vascular bundles in the stem cross section are usually scattered or more complex of an arrangement as compared to dicots.

Vascular Bundle of Dicots

• The vascular bundles in the stem cross section of dicots are arranged in a circle, or ring.

Comparison of Plants

• Monocot is on the left– Oat plant

• Dicot is on the right– Bean plant

• Notice the difference in the two plants

Characteristics of Dicots

Characteristics of Monocots