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Tissues and the Primary Growth Stems (Basic type of cells and tissues…
Tissues and the Primary Growth Stems
Internal organization of stems
Cortex
composed of photosynthetic parenchyma
has many specialized cells that secrete latex, mucilage or resin.
present interior to the epidermis
Vascular tissues
Phloem
transports sap. The sap is a water-based solution, but rich in sugars made by photosynthesis.
two types of conducting cells
Sieve cells
afford communication with similar adjacent cells
sieve pores arrange in circumscribed areas called called the sieve plane
walls contain perforations called sieve pores
Sieve tube membrane
have transverse end walls
Sieve tube membranes with proteins necessary for signaling and ATP in order to help them transfer molecules between different parts of the plant
transports organic compounds during photosynthesis
Xylem
conducts water and minerals
two types pf conducting cells
tracheids
long/narrow
the ends are pointed
reticulate
vascular elements
ends are usually flat
reticulate
short/wide
Basic type of cells and tissues
Collenchyma
Thin in some areas but thickened in other areas
present in elongating shoot tips
walls of collenchyma exhibits plasticity
present under epidermis or as bands located next to vascular bundle
Parenchyma
metabolically active, have primary walls that are thin
found in soft leaves, petals, fruits, and seeds
most common type of cell and tissue
chlorenchyma are parenchyma cells involved in photosynthesis
Sclerenchyma
cell walls are elastic
they can be deformed and and can be returned back to the original shape and size
has a primary wall and thick secondary wall
in mature organs sclerenchyma develops from parenchyma cells
Stem growth and differentiation
Apical meristem: new cells at the tip of the stem
Sub apical meristem
provascular tissue
primary xylem
primary phloem
fascicular cambium
secondary xylem
secondary phloem
cork cambium
protoderm
epidermis
cork cambium (in some plants)
phelloderm
cork
Ground meristem
pith
interfascicular cambium
cortex
cork cambium (in some parts)
vascular cambium
