PLB 400 Lecture Notes - Lecture 26: Vascular Cambium, Phloem, Tracheid
Document Summary
Roots: anchor plants and absorb water and minerals, store carbohydrates, production of hormones and secondary compounds (ex: ga, alkaloids for defence, nodules = bacterium capable of converting atmospheric nitrogen to nitrogen compounds, mycorrhizae fungus provide phosphorous. Root hairs epidermal cells that elongate, acnhoring, absorption. A schematic transverse section through part of an orchid root, showing specialised outer tissues. A mature velamen is dead and filled with air, but acts like a sponge when wetted. of water- repellent cells (p) provides a path for gaseous diffusion ( Velamen - inside the exodermis, it is many cell layers thick and capable of absorbing atmospheric moisture and nutrients grows from pericycle. Primary phloem gets pushed out because vascular cambium forms between xylem and phloem. Periderm - the protective coat that replaces the epidermis in plants during secondary growth, formed of the cork and cork cambium.
