PLANTS – DAY 3 MONOCOT & DICOTS

INTRODUCTION There are different classes of plants – one of these classes of plants are called angiosperms, and these plants produce flowers. Angiosperms can be further divided into 2 subclasses: Monocotyledoneae and the Dicotyledoneae, aka monocots and dicots Names of 2 subgroups are based on structure of their seeds

SEEDS The seed, which surrounds the plant embryo and protects it from desiccation in the uncertain conditions of a terrestrial environment, is one of the adaptations that has allowed plants to thrive as they gradually moved from water to land. Each seed consists of an embryo, food source, and protective outer coat; it can lie dormant for some time before germinating, waiting until environmental conditions are right Monocots have only 1 seed leaf, cotyledon Dicots have two cotyledon or seed leaves Cotyledons store nutrients/carbohydrates that nourish the embryo of the plant as it develops. Cotyledons are often the first leaf to appear as the seed germinates

MONOCOT & DICOT SEEDS

EXAMPLES OF MONCOTS & DICOTS: MONOCOTS: Onion, corn, rice, sugarcane DICOTS: tomatoes, cabbage, apples, peaches

SUMMARY OF DIFFERENCES: MONOCOTS DICOTS

TISSUE TERMS Vascular cambium/cylinder: meristematic tissue responsible for creating new xylem and phloem tissue Pith: the parenchyma tissue at the very center of roots AND stems. Functions in storage of nutrients, carbohydrates and water Cortex: parenchyma tissue surrounding the pith; made of rigid cells in roots AND stems Pericycle: a thin layer of lateral meristematic cells that surrounds the vascular cylinder; helps for secondary roots to grow Endodermis: layer of rectangular cells surrounding the vascular cylinder; innermost layer of the cortex; regulates movement of water and minerals Epidermis: the outermost layer of a multicellular plant experiencing growth Vascular Bundles: collections of xylem and phloem tissue, separate from other collections of cells, running longitudinally - includes xylem and phloem

ROOT TISSUE DIFFERENCES Xylem in center of root in an ‘X’ shape; phloem is outside of xylem Vascular bundles are arranged in a ring shape

MONOCOT ROOT CROSS SECTION

DICOT ROOT CROSS SECTION CORTEX EPIDERMIS

STEMS – MONOCOT & DICOT

DICOT STEM CROSS SECTION In herbaceous dicots, bundles are arranged in a ring A thin layer of tissue called vascular cambium between xylem and phloem – can appear as a hollow area in the plant (buttercup)

MONOCOT STEM CROSS SECTION MONOCOT STEM VASCULAR BUNDLE Herbaceous monocots have vascular bundles scattered throughout the stem (corn)