Transcript Leaves
Part 3 Roots, Stems & Leaves Structure of Plants •The structure of a plant contains a shoot system and a root system. Plant Tissue Systems • Plants consist of 3 main tissue systems: Dermal tissue Vascular tissue Ground tissue Plant Tissue Systems DERMAL TISSUE: • The outer covering of a plant Plant Tissue Systems VASCULAR TISSUE: • Forms the transport systems within the plant • Includes xylem & phloem Plant Tissue Systems GROUND TISSUE: • Cells that lie between the dermal and vascular tissues. Types & Functions of Roots •The root system includes those parts of the plant below ground, such as the roots, tubers, and rhizomes. •Taproots are found mainly in dicots. •Fibrous root systems are found mainly in monocots. •The function of all roots is to anchor the plant in to the ground & absorb water and nutrients from the soil. Stem Structure & Functions Stem Structure & Functions In general, stems have 3 important functions: 1.) to produce leaves, branches & flowers 2.) to hold the leaves upright towards the sun 3.) to transport substances between roots & leaves Parts of a Stem Types of Stems Recall from your previous plant notes: • Herbaceous – soft, green • Woody – dark, rigid Stem Arrangements • The leaves on a plant have one of the following 3 arrangements: ALTERNATE OPPOSITE WHORLED Stem Growth • Primary growth of a stem occurs when there is an increase in plant growth from the tips of the roots and the shoots. • In other words, the plant grows in height. Stem Growth • Secondary growth of a stem occurs when there is an increase in the width of a plant. Modified Stems • Many kinds of plants have modified stems that store food. • Tubers, rhizomes, bulbs and corms are all types of modified stems that can remain dormant during cold or dry periods until favorable conditions return. TUBER ONION IRIS Leaves • Leaves are the primary photosynthetic organ of a plant • The structure of a leaf is optimized for absorbing light and carrying out photosynthesis, as well as performing transpiration (water loss) and gas exchange by giving off O2 and taking in CO2. Leaves • Leaves may differ greatly in shape, arrangement, margin and venation, but the structural features of most leaves are the same. Leaf Arrangements Leaf Shapes Leaf Margins Leaf Venation Anatomy of a Leaf • The leaf provides food for the rest of the plant through the process of photosynthesis. • The outermost layer of the leaf is the epidermis, which is protected by the waxy coating of the cuticle. • Guard cells implanted in the epidermis form pores, known as stomata, through which water, oxygen, and carbon dioxide pass. Leaf Structure & Function • Leaves depend on stomata, which are pore-like openings on the underside of each leaf that allow CO2 and O2 to diffuse into & out of the leaf. • Plants can regulate the opening and closing of their stomata to balance water loss with the rates of photosynthesis. Leaf Structure & Function Lets see what you learned…. • REVIEW>>>REVIEW>>>REVIEW Types of leaves • ______ = one entire blade • ______= (divided leaf blade = leaflets) – Palmately – leaflets come together at a central point – Pinnately – leaflets attach to the petiole in a pattern resembling a feather Types of leaves • Simple = one entire blade • _____= (divided leaf blade = leaflets) – Palmately – leaflets come together at a central point – Pinnately – leaflets attach to the petiole in a pattern resembling a feather Types of leaves • Simple = one entire blade • Compound (divided leaf blade = leaflets) – Palmately – leaflets come together at a central point – Pinnately – leaflets attach to the petiole in a pattern resembling a feather Leaf Margin • _______ • ______________ • ______ Leaf Margin • Smooth • _____________ • ______ Leaf Margin • Smooth • Toothed (serrated) • ______ Leaf Margin • Smooth • Toothed (serrated) • Lobed Leaf Venation • ___________ – Monocots • __________________ –Dicots – Palmate venation – Pinnate venation Leaf Venation • Parallel veins – Monocots • __________________ –Dicots – Palmate venation – Pinnate venation Leaf Venation • Parallel veins – Monocots • Netted (branched) veins –Dicots – Palmate venation – Pinnate venation ______Leaf Simple Leaf __________ Leaf Compound Leaf Did you know??? Carnivorous Leaves • The 2 lobes of a Venus's-flytrap leaf form a deceptively safe and attractive landing place for insects and other animals. • Less than a second after this frog trips the trigger bristles on the inside surface of the leaf, the lobes close enough to trap him below interlocking spines. • If sensory organs determine that the frog contains protein, the leaf closes further and the plant's digestive enzymes start to flow.