Lecture 8 Flashcards
what does the lateral meristem compose of
vascular cambium and cork cambium
what does the cork cambium make which eventually replaces what
periderm and epidermis
what does the vascular cambium produce
secondary vascular tissue growth
what are the two types of perennials
herbaceous and woody
what are the two types of woody perennials
deciduous and evergreen
which perennials have secondary growth
woody; herbaceous does not have secondary growth
which type of woody perennial drops their leaves
deciduous
what are the two types of initials
fusiform and ray
where are initials found
in the vascular cambium
how are fusiform initials oriented
vertically oriented and very long
how are ray initials oriented
horizontally oriented and squarish
where do secondary xylem and phloem arise
from fusiform initials
where do vascular rays arise from
ray initials
what do vascular rays consist of
primarily parenchyma cells
how does temperate and tropical weather affect the vascular cambium
Temperate regions have winter where growth goes dormant; Tropics – plants MAY exhibit continual cambial activity
where are the fascicular and interfascicular cambium located
in the vascular cambium
what is the difference between fascicular and interfascicular cambiums
fascicular cambium comes from the pro cambium inside the vascular bundles; interfascicular cambium comes from the parenchyma cells between the vascular bundles
what does the fascicular and interfascicular cambium make when they eventually join
secondary tissue
where does the first cork cambium derive from
cortex
what is in the periderm
cork cambium, cork, phelloderm
what is cork
inner wall surfaces lined by layers of suberin and wax (may become lignified)
what are phelloderm
living parenchyma cells
how is secondary growth of the stem different than secondary growth of the root
Cork cambium arises from cortical cells as apposed to the pericycle; The cortex does not become sloughed off in 1st year like in roots; Has a pith unlike roots
what are lentils
allow for gas exchange through the periderm
what is bark
Includes all tissue outside of vascular cambium(phloem, cortex, & periderm); 2 layers: inner (living) and outer (dead)
what type of wood is conifer wood
softwood
what does conifer wood consist of
no vessels and resin ducts
what are resin ducts
Ducts lined with parenchyma cells that secrete resin; Possibly a mechanism of healing
what are rays made up of
tracheids and parenchyma cells
almost all wood in softwood is made up of what
tracheids
how do early wood cells differ from late wood cells
early wood cells are wider and have thinner walls, late wood cells are smaller and have thicker walls
when is early wood produced and when is late wood produced
early wood is produced in the spring when there is lots of water available, late wood is produced later in the season when there is less water available
what type of wood is angiosperm wood
hardwood
what does hardwood have that softwood does not
vessels
what makes up a large percentage of wood in angiosperms
rays
how are growth rings different in early and late wood
early wood is less dense, late wood is dense
what produces a false annual growth ring
Abrupt changes in available water and other environmental factors may be responsible for the production of more than one growth ring in a given year
what is sapwood
part of living tree that contains living cells and reserve materials
what is heartwood
the non-conducting often darker wood in a living tree
what is reaction wood
a developmental response by a leaning branch to counteract the force of gravity
what gives wood strength
density (mainly due to the structure of the fibers)
