Post on 16-May-2020
Chapter 23a-Angiosperms
How do angiosperms differ from gymnosperms?
The most diverse group of plants, with about 14,000 genera
and 257,000 species.
In double-fertilization, the two sperm nuclei in the
pollen tube each participate in a fertilization event.
4) Another key feature in angiosperms is the rapid reproductive cycle.
Angiosperms can have very rapid reproduction,
1)The ovules of angiosperms are borne inside
carpels, instead of on scales as in gymnosperms.
2) Angiosperms have flowers instead of the cones of gymnosperms.
3) A unique part of the life cycle of angiosperms is double-
fertilization.
Many gymnosperms are slow growing and have lengthy reproductive cycles.
Major Angiosperm Clades
The relationships of major angiosperm
groups are modeled after the Angiosperm
Phylogeny Group 2009 system
(APGIII 2009).
APG III 2009
-classifies one to several families into orders where there is strong evidence that the order is monophyletic
-these designated orders do not represent a hierarchical classification system
Orders can be viewed as convenient placeholders for 1 or more families that appear to comprise a monophyletic group.
Some monophyletic groups that contain several orders are given names.
Ex: Magnoliids
Basal Angiosperms
Major Angiosperm Clades
Basal angiosperm groups:
Many phylogenetic analyses agree in placing Amborella trichopoda (Amborellaceae) as sister to all of the flowering
plants.
Amborella trichopoda is a small, evergreen, shrub of New Caledonia.
This means that Amborella trichopoda is a descendent
It only occurs in the moist, shaded understory of tropical mountainside forests.
Nymphaeaceae
Nymphaeaceae-Arkansas flora
Nymphaeaceae (water lilies)
and Cabombaceae (water shields) are
successive sister groups to all other
angiosperms.
The water lilies represent the form of basal
angiosperms.
Radially symmetrical flowers with tepals
(undifferentiated petals and sepals).
Nuphar advena [syn. N. lutea]
Nymphaea odorata subsp. odorata [syn. N. odorata]
The old group dicot included all the angiosperms other than Monocots.
Basal Angiosperms
Dicot is no longer used to designate an angiosperm lineage because it is not monophyletic
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Monocot Eudicot
Recent molecular studies do not support the simple
division of angiosperms into dicots and monocots.
The core angiosperms comprise three lineages:
The Magnoliids
Mostly tropical, subtropical, and
warm temperate.
The Magnoliids include many
commercially important plants including:
For many years, the simple Magnolia
flower was thought to represent the
primitive angiosperm flower
The seeds are borne on an
almost cone-like structure
Myristica fragrans Persea americana Piper nigrum
Magnolia grandiflora Asimina triloba
Sassafras albidum
Magnoliids common in Arkansas include:
The Monocots
Monocots are distinguished from other
angiosperms by the presence of a single
cotyledon (seed leaf).
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Major monocot groups are the
Note the flower parts in threes and
the leaves with parallel venation, all
typical of monocots.
Monocots in the human diet
The Eudicots
The eudicots are separated from all other
angiosperms by a special pollen form.
Basal Angiosperms
The eudicots include three major lineages.
Core eudicot food plants, with rosids (green branch) and
asterids (red branch) collapsed.
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Tricolpate pollen
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The Eudicots
Rosid major clades with food species
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Rosid major clades with food species
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Food in the fabids
Food in the malvids
Flowers
The parts of the flower are arranged in successive
whorls above the receptacle.
The next whorl of the flower is the androecium, comprised
of stamens.
The final whorl is the gynoecium, the female part of the flower.
At the base of the pistil is the ovary, where the egg cells are formed and fertilization occurs.
The first whorl is composed of sepals.
The sepals are collectively referred to as the calyx.
The second whorl is made up of petals.
The petals are collectively referred to as the corolla.
The petals and sepals together are called the perianth.
The stamens have 2 parts, the slender filament and the
anther, which rests on top of the filament.
The androecium is the male portion of the flower, where
the pollen is produced.
The gynoecium comprises one or more carpels.
The pistil can either be a single carpel or multiple carpels
fused together.
An elongate style elevates the stigma above the ovary.
The stigma is where pollen lands, which is the first step toward fertilization of the egg.
The Androecium: structures of the anther.
Each microsprocyte undergoes meiosis to produce
four haploid microspores.
The pollen grain wall has a pattern that varies widely
among different types of angiosperms.
When the pollen grains are mature, the anther
walls break open and the pollen is released.
Through the process of pollination, the pollen is
transported to the stigma of the same or a different
flower.
Each pollen sac produces a number of microsporocytes.
The nucleus of each microspore then divides without
cytokinesis to form the pollen grain with 2 nuclei.
The pollen grain germinates,
The Gynoecium: structures of the carpel.
More often, there are several
separate carpels or fused
carpels.
Inside the locules, the ovules are
attached to the ovary by special tissue
called placenta (plural placentae).
Study outline for Chapter 23a-Angiosperms
Name four ways that angiosperms differ from gymnosperms.
Define double-fertilization.
The relationships of major angiosperm groups are modeled after the _________________________.
Name the basal angiosperm groups.
Describe specific characteristics for Amborella.
Describe specific characteristics for the water lily group.
What are the core angiosperm lineages?
Describe specific characteristics for the Magnoliids
Name three commercially important plants that are included in the Magnoliids.
Name three plants that are common in Arkansas and included in the Magnoliids.
What are the main differences between eudicots and monocots?
Describe general characteristics for monocots.
Name food examples for monocots.
Name the 3 main eudicot lineages.
Name food examples for the core eudicots.
Name food examples for the asterids.
Name food examples for the rosids.
simple pistil
The ovary has one to several
chambers called locules.
Study outline for Chapter 23a-Angiosperms
Define the following terms and label the image provided:
receptacle
perianth
androecium
gynoecium
sepal
calyx
petal
corolla
stamen
anther
filament
carpel
pistil
stigma
style
ovary
Define the following terms for the structure of the androecium, label the image provided and answer the questions:
anther
pollen sacs
microsporocytes
microspores
pollen grain
generative cell nucleus
tube cell nucleus
germinated pollen grain
pollen tube
What cell division process happens here?
What cell division process happens here?
How many microspores?
Haploid or diploid? What is the male gametophyte?
What is the difference between a simple and a compound pistil?
Define locule.
Define placenta.