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Tissues and the Primary Growth of Stems (Angiosperms (Monocots (Palms,…
Tissues and the Primary Growth of Stems
Angiosperms
Largest division in the plant kingdom
approximately 297,000 species
Basal Angiosperms
Magnolias
Waterlilies
Laurels
Monocots
Palms
Cattails
Philodendrons
Lilies
Bromeliads
Grasses
Eudicots
broadleaf plants
Asters
Maples
Roses
Plant Bodies
Herbaceous Body
Primary Plant Body
Woody Body
Secondary Plant Body
Herb
Plant that never becomes woody and covered with bark, often lives less than a year.
Snapdragons
Petunias
Beans
Corn
Wheat
Many live and grow for years
Irises
Lilies
Three Basic classes based on cells
Collenchyma
Have a primary wall that remains thin in some areas but becomes thickened in other areas, most often in the corners
Parenchyma
Have only primary walls that remain thin
Parenchyma Tissue is a mass of parenchyma cells
Most common type of cell and tissue, consulting all soft parts of a plant
Petals
Soft Leaves
Fruits
Seeds
Active metabolically and usually remain alive after they mature
Examples
Glandular Cells
Parenchyma cells that secrete nectar, fragrances, mucilage, resins, and oils
Transfer Cells
Parenchyma cells involved in photosynthesis
Chlorenchyma Cells
Parenchyma cells that mediate short-distance transport of material by means of a large, extensive plasma membrane capable of holding numerous molecular pumps
Sclerenchyma
Has both a primary wall and a thick secondary wall that is almost always lignified
These walls are elastic. They can be deformed, but return to their original size and shape when pressure is released
Two types of Cells
Conducting Sclerenchyma
Long and narrow tracheid's with tapered ends, containing no perferations
Mechanical Sclerenchyma
Subdivided into long fibers and short scleroids, both of which have elastic secondary walls
External Structures of Stems
All flowering plants have the same basic stem organization
Nodes
Leaves are attached here
Internodes
The region between nodes
Phyllotaxy
The arrangement of leaves on the stem
Leaf Axil
Axillary Bud
The bud is covered by small, corky, waxy bud scales that protect the delicate organs inside
A miniature shoot with a dormant apical meristem and several young leaves.
Terminal Bud
At the extreme tip of each stem
Internal Structures of Stems
Epidermis
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The outermost surface of a herbaceous stem
A single layer of Parenchyma cells
All interchange of material between a plant and its environment occurs by means of its epidermis
Cortex
Interior to the epidermis
Composed of photosynthetic parenchyma and sometimes collenchyma
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Vascular Tissues
Two types
Xylem
Conducts water and minerals
Two types of conducting cells
Vessel elements
Tracheary element
Tracheids
Phloem
Distributes sugars and minerals
Two types of conducting cells
Sieve cells
Sieve element
Sieve tube members
Stem Growth and Differentitation
Apical meristems
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Stems grow longer by creating new cells at their tips
Cells divide by mitosis and cytokinesis, producing progenitor cells for the rest of the stem
Primary tissues
The tissues produced by apical meristems
Primary growth
The growth and tissue formation that results from apical meristem activity
Subapical meristem
Region just below apical meristem
Cells dividing and growing
