• Prop roots are adventitious roots that can grow

extensively through the air

• Additional nutrients and water to the stem

• Stabilize stems-brace them against wind and water

currents

Banyan Tree

Root Modifications Plant Morphology

Stilt Roots in palm tree- Iriartea

Prop Roots Ficus benghalensis

Root Modifications Plant Morphology

• Climbing roots

Adventitious roots are formed at nodes which help

in climbing.

Betelnut plant

Root Modifications Plant Morphology

• Epiphytic roots

Base of tissue grows spongy tissue termed velamen

that absorbs moisture from the air.

Vanda

Root Modifications Plant Morphology

• Floating roots

White spongy roots filled with

air help plants to float-Jussiaea

Root Modifications Plant Morphology

• Aerial roots of orchids have a

specialized epidermis called a

velamen.

– Many orchids are epiphytic

– They grow on trees, with roots

dangling in the air

– The waterproof velamen prevents water

loss if the air becomes dry

Root Modifications Plant Morphology

• Contractile roots are important for stability and depth

control

– Prop roots can undergo considerable

contraction

– Root contraction may be important in

anchoring newly germinated seeds

– Bulbs and corms use contractile roots to

change their depth in the soil.

Contractile roots keep

underground roots at proper

Levels- Colacasia

Root Modifications Plant Morphology

• Haustoria are highly modified

roots of parasitic plants

• Haustorial roots are modified to:

Attach the parasite to the host

Penetrate the host vascular tissue

• Haustorial Roots

Root Modifications Plant Morphology

• The haustoria penetrates the epidermis and cortex

then continues until it makes contact with the

host’s xylem A continuous vessel from host to parasite forms, constructed of

cells of both

Parasites that only attack the xylem

photosynthesize

Others that do not photosynthesize

also attack the phloem

Root Modifications Plant Morphology

Mycorrhizae-not a root!

Mycorrhizae on pine roots

Mycorrhizae are mutualistic

associations between the roots of

seed plants and soil fungi Fungi gains carbohydrates from the

roots

Fungal hyphae helps with in

phosphorus uptake

Root Modifications Plant Morphology

There are two types of mycorrhizal associations:

1. Ectomycorrhizae: fungal cells penetrate between the

outermost root cortex cells but never penetrate the cell

wall; typically woody species

2. Endomycorrhizae: fungal cells penetrate the root

cortex and cell walls but not the plasma membrane.

The fungus is unable to live without these sugars

Often the plant becomes stunted without the fungus, probably

due to phosphorus deficiency

Root Modifications Plant Morphology

Mycorrhizae

Root Modifications Plant Morphology

Adventitious root

From unusual locations on above ground parts

Root Origin Plant Morphology

Roots arise from lamina, petiole,veins-Bryophyllum

Adventitious root

From unusual locations on above ground parts

Root Origin Plant Morphology

Plant Morphology

Shoots

Shoot Terminology

• Trunk-main shoot

• Scaffold/primary branch

• Angle-of-attachment

• Shoulder ring

• Leaf & leaf bud

• Leaf scar

• Flower & flower bud

• Terminal bud-apical meristem

• Axillary bud/ Lateral bud

• Node/internode

• Mixed bud vs. simple bud

Plant Morphology Shoots

• Growth: During the growing season, cell division and elongation are occurring in

both the apical and lateral meristems of dicots. This results in plant growth. The same

things are occurring in the intercalary meristems of monocots.

• Photosynthesis: When young and containing chlorophyll

• Reproduction

• Support

• Conduction Stems contain vascular tissue (xylem and phloem). Xylem conducts water and minerals.

Phloem conducts the sugars created during photosynthesis.

• Storage: Stems are sometimes modified to store food and (or) water(succulents)

Shoot Function:

Plant Morphology Shoots

Woody Dicot Stems

Plant Morphology Shoots

• Nodes: places on stems where leaves or buds are located.

• Leaf axil: where a leaf petiole attaches to a stem (the angle

created by the intersection of the petiole and stem).

• Internodes: the sections of a stem located between the

nodes.

Leaf blade

Petiole

Leaf Axil

Plant Morphology Shoots

Node

Woody Dicot Stems-cont.

Plant Morphology Shoots

• Bud: a structure on a stem containing a dormant apical

meristem.

Buds are usually, but not always, covered by protective

scales.

Can be terminal or lateral in position.

Come in 3 basic types:

• Vegetative

• Flower

• Mixed

Woody Dicot Stems-cont.

Plant Morphology Shoots

Bud scales

Naked bud of

V. carlesii

Woody Dicot Stems-cont.

Terminal bud

Lateral buds

Woody Dicot Stems-cont.

Plant Morphology Shoots

Plant Morphology Shoots

Mixed buds of Lilac are opening up to reveal both

stems/leaves and flowers.

Woody Dicot Stems-cont.

• Terminal bud scale scars: mark the location of last seasons

terminal bud.

• Leaf scars: scars marking the location of last seasons

leaves.

• Vascular bundle scars: found inside leaf scars, these scars

mark the location of the vascular bundles that passed from

the stem, through the leaf petiole, and into the leaf blade.

• Lenticels: dot-like structures on stems that consist of

loosely packed cells that may play a role in gas exchange

between the atmosphere and stem. Not all stems have

lenticels.

Plant Morphology Shoots

Woody Dicot Stems-cont.

Plant Morphology Shoots

Woody Dicot Stems-cont.