BDE 264
Plant Form
Written by Tegan Gibaud
Introduction
Definitions Physiology: The way in which a living organism or bodily part
functions.
Anatomy: A study of the structure or internal workings of
something.
Vascular: Relating to plant tissues (xylem and phloem) which
conduct water, sap, and nutrients in flowering plants, fern and their
relatives.
Plant Form Plant form is a way of describing plant anatomy.
James Mauseth was an American botanist who famously said
“Anatomy based on function requires very little memorization, but it
demands constant thinking, constant analysis, and a constant
consideration for individual structures on individual species and
their own particular biologies.”
Plant Anatomy Plant anatomy is a dynamic process and not static. Plant anatomy
is a framework in which plant metabolism functions.
The cells, tissues and organs of the plant are a result of its
metabolism and external environment.
Natural Selection Aspect
● Structures and their variation can be related to a need from
that plant that must be fulfilled.
● The environments therefore shape the plant.
● This is limited to the plant’s physiology due to natural
selection.
● Natural selection will predetermine certain factors of the
plant.
Structure of Plants There is great variation in the structures of plants. The structures
may be beneficial or detrimental and functional or non-functional.
This depends on the plant biology (microhabitat, climate,
pollinators, pathogens, competition).
When a plant structure is examined, the physiology, growth
reproduction and survival mechanisms must be considered in
conjunction with the plant as these affect the plant’s structure.
1
,Main Focus: Vascular Vascular plants will be the focus of this topic, specifically seed
Plants plants.
Vascular plants are described as plants with conducting tissue
(xylem & phloem).
Non-vascular plants do not have these tissues.
Image: Source Unknown
In the diagram below, the 4 right most plants have vascular tissue.
In these plants, there are 3 plant organs: Roots, stems and leaves.
Image: Source Unknown
2
, External & Internal Organization of Plant Body
Plant Body Organization The ground plan of plants includes external and internal
structures.
3 Basic Organs
● Roots
● Stems
● Leaves (these can be arranged on a stem in different
ways)
All three of these basic organs have their own meristems.
Meristems: Stem Vertical growth of the stem is facilitated by apical meristems.
Stem elongation is enabled via cell division. New stem tissue is
produced as well as primordia (beginning of a leaf) which
mature into new leaves.
A group of cells remain meristematic just above each leaf
primordium after lead maturation.
At the leaf primordium stage, the meristems are axillary
meristems and as the leaf primordium matures they become
axillary buds.
Image: http://www.sbs.utexas.edu/mauseth/weblab/webchap6apmer/6.1-1.htm
Axillary buds can remain dormant or can be activated to give rise
to a new branch, flower, inflorescence or modified shoot. These
shoots look different to normal shoots and have a specialized
function.
3
, Meristems: Roots Vertical growth of roots are also achieved by an apical meristem
near the root tip.
There is a protective layer around the root apex (the root cap)
which protects the apical meristem. Axillary buds are absent.
The branch roots develop from within existing roots.
The apical meristem of the root only gives rise to the main root.
Image:
https://organismalbio.biosci.gatech.edu/growth-and-reproduction/plant-develop
ment-ii-primary-and-secondary-growth/
Cellular Structure of Plants All higher plants are multicellular (many cells and cell types).
The multicellularity enables divisions of labour and leads to the
specialization of cells.
Some cells are responsible for transport, reproduction, support
or absorption.
There is, however, a drawback as there is an interdependence
between cells. If essential tissues are damaged, the plant may
die. If trees are ring barked, they will die due to this.
4
Plant Form
Written by Tegan Gibaud
Introduction
Definitions Physiology: The way in which a living organism or bodily part
functions.
Anatomy: A study of the structure or internal workings of
something.
Vascular: Relating to plant tissues (xylem and phloem) which
conduct water, sap, and nutrients in flowering plants, fern and their
relatives.
Plant Form Plant form is a way of describing plant anatomy.
James Mauseth was an American botanist who famously said
“Anatomy based on function requires very little memorization, but it
demands constant thinking, constant analysis, and a constant
consideration for individual structures on individual species and
their own particular biologies.”
Plant Anatomy Plant anatomy is a dynamic process and not static. Plant anatomy
is a framework in which plant metabolism functions.
The cells, tissues and organs of the plant are a result of its
metabolism and external environment.
Natural Selection Aspect
● Structures and their variation can be related to a need from
that plant that must be fulfilled.
● The environments therefore shape the plant.
● This is limited to the plant’s physiology due to natural
selection.
● Natural selection will predetermine certain factors of the
plant.
Structure of Plants There is great variation in the structures of plants. The structures
may be beneficial or detrimental and functional or non-functional.
This depends on the plant biology (microhabitat, climate,
pollinators, pathogens, competition).
When a plant structure is examined, the physiology, growth
reproduction and survival mechanisms must be considered in
conjunction with the plant as these affect the plant’s structure.
1
,Main Focus: Vascular Vascular plants will be the focus of this topic, specifically seed
Plants plants.
Vascular plants are described as plants with conducting tissue
(xylem & phloem).
Non-vascular plants do not have these tissues.
Image: Source Unknown
In the diagram below, the 4 right most plants have vascular tissue.
In these plants, there are 3 plant organs: Roots, stems and leaves.
Image: Source Unknown
2
, External & Internal Organization of Plant Body
Plant Body Organization The ground plan of plants includes external and internal
structures.
3 Basic Organs
● Roots
● Stems
● Leaves (these can be arranged on a stem in different
ways)
All three of these basic organs have their own meristems.
Meristems: Stem Vertical growth of the stem is facilitated by apical meristems.
Stem elongation is enabled via cell division. New stem tissue is
produced as well as primordia (beginning of a leaf) which
mature into new leaves.
A group of cells remain meristematic just above each leaf
primordium after lead maturation.
At the leaf primordium stage, the meristems are axillary
meristems and as the leaf primordium matures they become
axillary buds.
Image: http://www.sbs.utexas.edu/mauseth/weblab/webchap6apmer/6.1-1.htm
Axillary buds can remain dormant or can be activated to give rise
to a new branch, flower, inflorescence or modified shoot. These
shoots look different to normal shoots and have a specialized
function.
3
, Meristems: Roots Vertical growth of roots are also achieved by an apical meristem
near the root tip.
There is a protective layer around the root apex (the root cap)
which protects the apical meristem. Axillary buds are absent.
The branch roots develop from within existing roots.
The apical meristem of the root only gives rise to the main root.
Image:
https://organismalbio.biosci.gatech.edu/growth-and-reproduction/plant-develop
ment-ii-primary-and-secondary-growth/
Cellular Structure of Plants All higher plants are multicellular (many cells and cell types).
The multicellularity enables divisions of labour and leads to the
specialization of cells.
Some cells are responsible for transport, reproduction, support
or absorption.
There is, however, a drawback as there is an interdependence
between cells. If essential tissues are damaged, the plant may
die. If trees are ring barked, they will die due to this.
4
