Structure of Woody Plants Flashcards
Primary Growth
- growth in length
- production of leaves
- production of branches
Secondary Growth
Growth in girth in:
- stems
- roots
Primary Tissues
- epidermis
- cortex
- vascular bundles
- pith
- leaves
Secondary Tissues
- wood
- bark
wood
secondary xylem
bark
secondary phloem and cork
Important consequence of secondary growth and production of woody body in plants
- stability
- protection (herbivores and harsh environment)
- longer lifespan
Disadvantage of secondary growth and production of woody body in plants
- utilize more energy
- increase in height (water and nutrient can’t be easily distributed)
How many times did the evolution of secondary growth happen in 420 million years of the existence of vascular plants
3 times
When did the evolution of secondary growth happen
370 million years ago
Where did the secondary growth evolve from
one group of ancestral woody vascular plants that include all seed plants
_____ is a new phenomenon within the flowering plants
herbaceousness
Presence of Secondary Growth in modern ferns
absent in all species
Presence of Secondary Growth in gymnosperms
present in all species
Presence of Secondary Growth in dicots
present in many species, but many other species are herbs
Presence of Secondary Growth in monocots
ordinary type is absent in all species, but some have anomalous secondary growth
Example of monocots with secondary growth
- palm trees
- yucca plant
Why can’t monocots have secondary growth
because of scattered vascular cambium
Two types of cells in vascular cambium
- fusiform initials
- ray initials
What makes up the vascular cambium
- interfascicular cambium
- fascicular cambium
A strip of cambium that originates from the procambiun is present between the xylem and phloem of the vascular bundle
fascicular cambium
The cambial layer formed between the two vascular bundles
interfascicular cambium
studies trees and shrubs in order to improve the health and safety of the individual plants
arborist
technique that kills woody plants in place without cutting them down
Girdling
Vascular cambium: After one year of growth
secondary xylem
Vascular cambium:
After two years of growth
secondary phloem
direction of secondary growth
outwards
Secondary xylem
late wood + early wood
Periderm
cork cambium + cork
an undifferentiated meristematic tissue found in the buds and growing tips of roots in plants
apical meristem
primary meristems
- Protoderm
- Ground meristem
- Procambium
primary tissues
- Epidermis
- Cortex
- Vascular cylinder
apical meristem –> protoderm –> ___
epidermis
apical meristem –> ground meristem –> ___
cortex
apical meristem –> procambium –> ___
vascular cylinder
What are included in the vascular cylinder
- Pericycle
- Undifferentiated procambium
- Primary phloem
- Primary xylem
primary tissue of plant roots and is the site for the initiation of lateral roots and two secondary meristems
Pericycle
Pericycle gives rise to
- cork cambium
- vascular cambium
Undifferentiated procambium give rise to
vascular cambium
cork cambium give rise to
- cork
- phelloderm
cork, cork cambium, and phelloderm constitute the ___
periderm
vascular cambium gives rise to
- secondary phloem
- secondary xylem
Secondary tissues from pericycle and undifferentiated procambium
- cork
- phelloderm
- secondary phloem
- secondary xylem
produce radial files of parenchyma cells known as xylem rays and phloem rays that transfer water and nutrients laterally within the woody stem and in the storage of starch and other reserves
ray initials
elongated cells that form secondary xylem to the inside of the vascular cambium and secondary phloem to the outside
fusiform initials
tracheids in gymnosperm and dicots
Gymnosperm: present
Dicots: present
Vessels in gymnosperms and dicots
Gymnosperm: absent (except in 3 groups)
Dicots: present
Fibers in gymnosperms and dicots
Gymnosperm: very rare
Dicots: present
Parenchyma in gymnosperms and dicots
Gymnosperm: very rare
Dicots: present
Ray parenchyma in gymnosperms and dicots
Gymnosperm: present
Dicots: present
Ray tracheids in gymnosperm and dicots
Gymnosperm: present
Dicots: absent
What are included in the axial system
- tracheids
- vessels
- fibers
- parenchyma
the increment of wood added during a single growth period
growth ring
The portion of the branches enclosed within the woods
encased knots
At the very center and is the oldest part of the tree
pith
- dead, central wood of trees
- cells usually contain tannins or other substances that make it dark in color and sometimes aromatic
heartwood
the soft outer layers of recently formed wood between the heartwood and the bark, containing the functioning vascular tissue
sapwood
one of many raised pores in the stem of a woody plant that allows gas exchange between the atmosphere and the internal tissues
lenticel
form a barrier to the apoplastic flux, forcing ions to pass through the selectively permeable plasma membrane into the cytoplasm, rather than move along the cell wall
Casparian strip
what is the Casparian strip made out of
suberin
exodermis are made out of
sclerenchyma
cortex are made out of what cells
parenchyma cells
