Plant Identification

Roots, Stems, Leaves and Flowers are the Criteria.

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.

Terminology

In order to be able to identify a plant and put it in the right family, you need to know the terminology to use.

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.

Plant Identification

The following sections (roots, stems, leaves and flowers) will show you how to use these for plant identification purposes.

Roots

The type of root will normally help you identify the plant. It will place the plant into a monocot or dicot category.

Types of Roots

Tap RootHave a main central root and

may have some lateral branching

E.g. Carrots

Types of Roots

Penetrate the soil to various depths - some only a few feet, others like the mesquite to as deep as 114 ft.

Types of Roots

FibrousHave 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

This root system can effectively prevent any other plant from becoming established – ex: grasses - idea of a healthy lawn is to compete with weeds

Types of Roots

Adventitious Buds - commonly develop on stems or roots - ex: stolons and rhizomes (Bermuda grass, cherry tree, Sumac and raspberry suckers)

Types of Roots

Prop Roots - augment regular roots for anchorage aid - ex: corn - roots come out above soil and help hold plant up

Types of Roots

Aerial Roots - extend down from the branches into the soil - ex: banyan trees

Pneumatophores- stick up from the mud for the purpose of absorbing oxygen – ex: cypress and mangrove

Types of Roots

Mycorrhizal fungi roots - form associations with soil fungi and act as root hairs increasing the absorption of water and minerals (symbiotic relationship - mutually beneficial) – found on trees in temperate forests such as pines and also on ferns, lettuce, white clover, perennial rye and orchids

Types of Roots

Haustorial - parasitic roots which not only anchor but also penetrate into the hosts vascular system for water and nutrients – ex: mistletoe

Types of Roots

Storage roots - starch and other molecules are stored for growth or flowering needs (ex: carrots, beets and turnips)

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.

Why Different Types of RootsAll plants are in competition with

each other for food and nutrientsBy having different types of roots,

the plants can reach different depths in the soil and still live side by side with other plants

Roots from Seeds – Monocot vs. Dicot Tap Root

Seeds contain an undeveloped plant (embryo)

Seed germination - embryonic root (radicle) grows by dividing and elongation of cells

Roots from Seeds

Forms one primary rootEx: dicots (two leaves

emerge from embryo), beans

Roots from Seeds cont.

Fibrous rootEmbryos of grasses have a

single radicle (root shoot)Also has other embryonic

roots (seminal roots) forming just above the radicle

Roots from Seeds cont.

All of these branch to form the fibrous root

Ex: monocots (one leaf emerges from embryo)

Dicot Seed

Monocot Seed

Stems

Flowering plants - divided into two groups, monocots and dicots - stems have major differences in arrangement, distribution of tissues and appearance.

Stems

For identification: type of stem (woody or herbaceous), monocot or dicot, has pubescence (hair) or not (glabrous), shape of stem (square – round), or contains glands.

Monocot stem

Dicot stem

Mature Structure of Woody vs Herbaceous StemsHerbaceous stems

Lack secondary growth - because plants only live one year/growing season (annuals)

Mature Structure of Woody vs Herbaceous Stems

Stems remain soft and flexible.

Buds lack protective scales (don’t need to survive harsh conditions)

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

Specialized Stems

Adventituous stems – can be either rhizomes or stolons.

Specialized Stems

Rhizomes - underground horizontal stems (ex: perennial grasses, bamboo) - may also serve as a storage function (irises) – will grow a plant and roots at a node.

Specialized Stems

Stolons - runners - usually above ground, horizontal stems (really elongated internodes) – will grow a plant and roots at a node - ex: strawberries

Specialized Stems

Tubers - several internodes at the end of an underground rhizome (ex: potatoes) - eyes are axillary buds – where the tuber will grow a plant

Specialized Stems

Bulbs - large bud with small stem at lower end - storage in the form of numerous, fleshy leaves - ex: onion, lily, tulip

Corms - look like bulbs, but are mostly stem tissue with a few, papery leaves on the outside - ex: gladiolus, crocus

LeavesLeaves are used as part of the

identification process along with the roots and stems.

Look of the leaf (margins, venation, and shape), arrangement and whether it is monocot or dicot.

Leaves

Leaves may contain pubescence, glands or thorn like projections.

All of these points are considered when using a leaf for identification.

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

Parts of a Monocot Leaf

Auricle – small appendages that extend out and sometimes around the stem – found at the junction of the blade and sheath – can be clasping or non clasping appendages

Parts of a Monocot Leaf

Collar – area between the leaf blade and sheath – auricles and ligules are on the inside of this area

Picture showing parts of a grass plant.

Differences Between Monocot and Dicot LeavesMonocots – 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

Monocot Leaf -Vein Arrangement

Dicot Leaf – Vein Arrangement

Vein

Midvein

Smaller lateral vein

Leaf Modifications

Tendrils – typically at the end of a compound leaf – enables plant to climb – ex: pea

Modifications

Stipules – occur at node where normal or true leaves arise from stem – are small leaf like structures at the base of petioles – may be leaf -like or spines (ex: locust)

Modifications

Spines – modified leaves – ex: cactus

Awn – on reproductive structure in grasses – extension of the lemma portion of the flowering structure

Modifications

Bracts – floral leaves that form at the base of a flower or flower stalk

Cotyledon – the embryo leaf in a seed - first leaf of a seedling – used for food storage

Flowers

Petals – are highly colored portions of the flower.May contain perfume (rose) or

nectar glands –to attract pollinators.Number of petals on a flower is

often used in the identification of plant families and genera.

Flowers

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

Monocots – have sepals in multiples of threes

Parts of a Flower

Petals

Stamens (anther & filaments)

Pistil (stigma,style & ovaries)

Sepals

Pedicel

Sepals

Receptacle

Pedicel

Parts of a Flower

Types of Inflorescence (Flowers) Raceme – inflorescence with the

flowers single on pedicels (stems) arranged along an elongated stem (rachis – this is the stem that is between the flowers) – alternate – oldest are at the bottom and the youngest are at the top. Ex: snapdragon, foxglove

Types of Inflorescence (Flowers)

Umbel – flat-topped inflorescence with the rachis non-existent. Ex: wild carrot, dill

RacemeFoxglove Snapdragon

UmbelDill

Types of Inflorescence (Flowers)Spike – type of inflorescence

with the flowers sessile (without a stalk) along the rachis. Ex: gladiolus

Head – a dense cluster of sessile or nearly sessile (no stalk) flowers on a very short rachis. Ex: sunflower, clover

Spike

Gladiolus

                    

Head

Clover

Sunflower

Types of Inflorescence (Flowers) Panicle – inflorescence with two or

more flowers on each branch which are attached to a rachis (elongated stem). Ex: wild oats, downy brome

Corymb – is made up of florets whose stalks and pedicles are arranged at random along the stalk in such a way that the florets create a flat, round top. Ex: yarrow

                                                                                 

Wild Oats

Downy Brome

Panicle

Corymb