Chapter 7: Plant Anatomy and Morphology: Monocots vs Dicots

Plant Anatomy and Morphology

• Monocots and dicots are two important groups of crops.
• Plant tissues are vascular, meristem, epidermis, and ground tissue.
• Plants have four organs: roots, stems, leaves, and flowers.
• Other important plant parts include fruits and seeds.

Monocots and Dicots

• Monocots have one cotyledon, usually herbaceous, parallel veins in leaves, scattered vascular bundles, fibrous root system, and hypogeal germination.
• Dicots have two cotyledons, can be herbaceous or woody, netted veins in leaves, vascular bundles in a ring, taproot system, and epigeal germination (usually).

Plant Tissues

• Epidermis is the outer, protective cell layer on stems and leaves, with a waxy cuticle that helps protect and absorbs water.
• Stomata are similar to the blood flow system in animals.
• Vascular tissue is conducting tissue that consists of xylem (water and nutrients) and phloem (sucrose or food).
• Ground tissue composes the bulk of the plant, consisting of pith and cortex.
• Meristems are areas of actively dividing cells, including apical (responsible for growth at tip of shoot or root), intercalary (responsible for growth of stem internodes and leaves), and axillary (responsible for development of buds for branches or flowers).

Plant Organs

• Roots anchor the shoot into the soil, support upright growth of stems, absorb minerals and water, and provide storage of energy reserves.
• Root systems can be taproot or fibrous, with dicots having one main root with other roots that splinter off.
• Stems are the primary supporting structure, a conduit for movement of water, nutrients, and photosynthesis products, and can also conduct photosynthesis and store energy.
• Leaves are the primary site for photosynthesis and transpiration, consisting of a sheath, blade, and collar in monocots and a petiole and blade in dicots.
• Flowers are modified leaves, generally having four parts: male stamen, female pistil, petals, and sepals, and can be categorized as complete or incomplete, perfect or imperfect.

Modified Stems

• Rhizomes are modified stems that grow underground, producing new plants.
• Stolons are modified stems that grow above ground, producing new plants.
• Tubers are modified stems that are swollen and underground, used for food storage.
• Bulbs are modified stems that are underground and composed of a short stem and scales.
• Corms are modified stems that are underground and swollen, used for food storage.

Inflorescences and Fruits

• Inflorescences are arrangements of flowers, including spikes, panicles, racemes, umbels, and heads.
• Fruits are ripened or mature ovaries containing the seed or seeds, classified as fleshy or dry.
• Seeds are mature, fertilized ovules or eggs within the ovary.