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.