Please enable JavaScript.
Coggle requires JavaScript to display documents.
Tissues and the Primary Growth of Stems (External Organization of Stems…
Tissues and the Primary Growth of Stems
Concepts
Being upright had an advantage but was difficult to also maintain the nutrients needed to live
stems evolved to transport water, support structures, produce and support leaves, and store sugars an nutrients.
stems can also be taken to new places and sprout roots
Basic Types of Cells and Tissues
Parenchyma
Thin Primary Walls. Typically alive at maturity. Many functions.
Chlorenchyma are parenchyma cells involved with photosynthesis. many chloroplasts.
Glandular cells that secrete nectar, fragrance, resin, and oil are also Parenchyma cells. conatin few chloroplasts. transport sugar and minerals into them.
Transfer cells are Parenchyma cells that transfer material using a plasma membrane.
some die at maturity to aid in releasing pollen or seeds from pods.
easy for plant to build as it takes minimal nutrients
Sclerenchyma
Primary walls plus secondary walls. Many dead at maturity. Provide elastic support and some are involved in water transport.
provides strength and flexibility to plant.
Collenchyma
Unevenly thickened primary walls. Typically alive at maturity. Provide plastic support.
used for support.
Uses more nutrients to produce.
External Organization of Stems
shoots grow in multiple ways
A vine can 'explore'
Rhizomes help plants explore underground
are horizontal rhizomes but are used mainly for storage.
Internal Organization of Stems: Arrangement of Primary Tissues
Epidermis
the outermost surface. A single layer of parenchyma cells.
some produce trichomes to make it difficult for animals to touch or eat.
Cortex
Interior to the epidermis
Vascular Tissues
Xylem
conducts water and nutrients from the roots
Phloem
moves sugars and other metabolic products down from the leaves.
Vascular Bundles
All vascular bundles contain Collateral; both xylem and Phloem strands running parallel to eachother
Stem Growth and Differentiation
stems grow by creating new cells at the tips.
differentiation begins when cells stop dividing and start elongating