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 plants Alternate – one leaf per node Opposite – two leaves per node Whorled – 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