Chapter 4: Morphology of Plants

Learn the idea

Roots usually anchor the plant and absorb water and mineral ions. The shoot includes stems, leaves, buds, flowers and fruits. Nodes are positions where leaves or buds attach; an internode is the length between nodes. A bud can develop into a shoot or flower.

Root structures and types

A root cap protects the growing tip. Root hairs increase the area available for absorption. A tap-root system has a main root with side roots; fibrous root systems have many roots of similar size. Adventitious roots arise from structures other than the embryonic root. Some roots store food, as in carrot.

Stem structures and functions

A stem supports above-ground parts and carries water, mineral ions and sugars through transport tissues. Strong stems can stand upright; weak stems may trail or climb with support. A potato tuber is a modified stem with buds, whereas a carrot is a modified root. Identify the plant structure, not merely its position underground.

Leaves and plant care

A typical leaf has a base, stalk (petiole) and blade (lamina) with veins. A simple leaf has one blade; a compound leaf has separate leaflets. Photosynthesis, gas exchange and transpiration are important leaf functions. Use fallen leaves or photographs for observation instead of uprooting plants unnecessarily.

Trace a root from tip to shoot

A root cap protects the tip, and the growing region behind it produces new tissue. Root hairs occur further back and increase absorption area. A tap-root system has a prominent main root; many grasses have fibrous systems. Adventitious roots originate from a stem or another non-embryonic-root structure. The categories describe origin and form, so they should not be treated as interchangeable names for every root.

Recognise stems and modifications

The stem’s nodes bear leaves or buds; internodes separate nodes. An axillary bud is found in the angle between a leaf and stem, while an apical bud is at a shoot tip. Some stems stand upright; others trail or climb. Ginger rhizomes and potato tubers are modified stems with buds; a carrot’s swollen storage structure is a root. A stem may be underground, so location alone is insufficient.

Examine a whole leaf

A leaf base joins the stem, a petiole is its stalk, and a lamina is the blade. Veins contain transport tissues. A simple leaf has one blade that may be lobed; a compound leaf is divided into leaflets. The axillary bud helps identify the whole leaf rather than one leaflet. Leaves exchange gases, make food in photosynthetic cells and lose water vapour by transpiration.

Plant parts in daily life

People use roots, stems and leaves as food, materials and sources of useful substances. Spinach is a leaf food; ginger is a stem example and carrot a root example. Root absorption, stem transport and leaf processes work as a connected system. Use fallen leaves, photographs or ordinary food specimens where possible. During observations, leave plants in place and avoid disturbing animals, nests or feeding sites.

Check a common mistake

Mineral ions from soil are not a plant’s complete food. Green plants make sugars through photosynthesis; roots supply water and mineral nutrients.

Identify a leaf rather than count pieces

A neem leaf contains several leaflets on one stalk. It is compound; the separate leaflets are not each whole leaves with their own axillary bud.

Explain a plant system

Water enters through roots, moves along stem transport tissues and reaches leaves. Leaves make sugars that can move to other plant parts. A drawing with arrows shows the connection more clearly than three unrelated labels.

Your written practice

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