Animal, Plant & Soil Science
E2-4
Flower Anatomy
Interest Approach
l  Begin a discussion on sexual reproduction. Ask what
students know about sexual reproduction in animals.
Although the initial responses may be slow, given
time, most students will be able to tell you about
animal reproduction. Now, switch to plant sexual
reproduction. What do students know? Are there girl
and boy plants? (Yes, sometimes.) Do plants have
sex ? (Yes.) Do plants have sperm and eggs? (Yes.)
Do plants have genitalia? (Yes, although we call
them flowers. )
Objectives
l  1 Identify the parts of flowers and explain
their functions.
l  2 Compare and contrast the types of flowers.
l  3 Define inflorescence and describe the types
of inflorescences.
Terms
l  _ anther
l  _ bract
l  _ calyx
l  _ catkin
l  _ complete flower
l  _ corolla
l  _ corymb
l  _ cyme
l  _ determinate
l  _ dioecious
Terms
l  _ filament
l  _ head
l  _ imperfect flower
l  _ incomplete flower
l  _ indeterminate
l  _ inflorescence
l  _ monoecious
l  _ ovary
l  _ panicle
Terms
l  _ pedicel
l  _ peduncle
l  _ perfect flower
l  _ perianth
l  _ petals
l  _ pistil
l  _ pistillate
l  _ pollen
l  _ raceme
l  _ receptacle
Terms
l  _ sepals
l  _ spadix
l  _ spike
l  _ stamen
l  _ staminate
l  _ stigma
l  _ style
l  _ tepals
l  _ umbel
What are the parts of a flower and their
functions?
l  I. Flowers are the most obvious part of most
plants. The purpose of flowers is for plants to
be able to reproduce sexually. They are made
of many intricate and important parts. Most
flowers contain both male and female parts.
What are the parts of a flower and their
functions?
l  A. The male part of a flower is called the stamen.
l  1. The stamen is made of the stalk-like filament
which holds up the sac-like anther.
l  2. The anther contains pollen, the grain released by
flowers, which contains the sperm.
l  3. Flowers that have only male parts are called
staminate.
What are the parts of a flower and their
functions?
l  B. The female part of a flower is called the pistil.
l  1. The pistil is made up of a sticky tissue at its end
called the stigma that is receptive to pollen.
l  2. Below the stigma is a rod-shaped middle part
called the style and a swollen base containing eggs
called the ovary. Once the pollen reaches the
stigma, it forms a pollen tube down through the style
to the ovary where sperm is deposited.
l  3. Flowers that have only female parts are called
pistillate.
What are the parts of a flower and their
functions?
l  C. Flowers often have parts that are neither male nor
female. These are the petals, usually colorful leaf-like
structures that often attract animals and insects.
l  1. When all the petals are fused together, they form a
corolla.
l  2. Beneath the petals are more leaf-like structures
that are often green, called sepals. The sepals
support the petals and protect the flower before it
opens.
l  3. When all the sepals are fused together, they form a
calyx.
What are the parts of a flower and their
functions?
l  4. Together, the petals and sepals are called the
perianth.
l  5. With some plants, a clear distinction between
petals and sepals cannot be made. In these cases,
the parts of the perianth are called tepals. Tulip
flowers and many monocots have tepals.
l  6. Some plants have modified leaves at the base of a
flower or floral inflorescence called a bract. The
bracts may be green but in some cases, such as the
poinsettia, are colorful.
What are the parts of a flower and their
functions?
l  D. The flower stem is referred to as the
pedicel. The portion of the pedicel that holds
the flower parts is the receptacle.
What are the types of flowers?
l  II. Flowers come in many shapes, sizes, and
colors. Not all of them have all the structures
previously mentioned.
l  A. Plants may produce flowers that are
perfect or imperfect.
l  1. A flower that has both male and female
parts is called a perfect flower.
l  2. A flower that is missing either male or
female parts is called an imperfect flower.
What are the types of flowers?
l  B. Plants may have flowers that are
complete or incomplete.
l  1. If a flower has sepals, petals, pistils, and
stamens, it is referred to as a complete
flower.
l  2. If a flower is missing one of these parts,
it is referred to as an incomplete flower.
l  3. Imperfect flowers are always incomplete.
Incomplete flowers may or may not be
imperfect.
What are the types of flowers?
l  C. Plants may be classified as
monoecious or dioecious.
l  1. Monoecious plants bear both male
and female flowers on one plant. Corn,
cucumbers, and oaks are monecious.
l  2. Dioecious plants have male and
female flowers on separate plants.
Soybeans, asparagus, kiwi, and hemp
are examples of dioecious plants.
What are the types of flowers?
l  D. A good way to tell the difference
between a monocot and a dicot is
to look closely at the flowers.
l  1. Monocots have flowers with
flower parts in multiples of three.
l  2. Dicots have flowers with flower
parts in multiples of four or five.
What is an inflorescence and what are
the types of inflorescences?
l  III. Flowers are borne on plant stems in one
of two ways. Some plants have solitary
flowers, such as the tulip, narcissus, and
rose. Other plants have flower clusters,
known as an inflorescence. An
inflorescence is actually the branching
system of the stem. The main stem of an
inflorescence is known as the peduncle.
Pedicels that branch from the peduncle
support individual flowers.
What is an inflorescence and what are
the types of inflorescences?
l  A. One way in which types of inflorescence are classified
is by the sequence of flowering within the flower cluster.
l  1. If the first flower to open is at the apex of the stem and
the progression of flowering is downward or outward, the
inflorescence is determinate. Some examples of
determinate flowers include liatris, kalanchoe, and African
violet.
l  2. If the last flower to open is terminal on the main axis
and the progression of flowering is inward or upward, the
inflorescence is indeterminate. Indeterminate types of
inflorescences are racemes, corymbs, heads, and
umbels. Freesia, cineraria, snapdragon, and stock also
have indeterminate inflorescence.
What is an inflorescence and what are
the types of inflorescences?
l  B. There a variety of inflorescence types. Some common
types are cyme, spike, raceme, panicle, corymb, umbel,
spadix, catkin, and head. The spike and the panicle types of
inflorescence are the most common among monocot plants.
l  1. A cyme takes on several forms, although it is usually a
flat-topped inflorescence.
u
u
u
a. A dichasium cyme bears a terminal flower on a peduncle with a pair
of branches that produce lateral flowers. It may be simple or
compound.
b. A monochasium cyme has a terminal flower and, below it, one
branch that produces a single lateral flower. The terminal flower is the
oldest.
c. Tomato, potato, and alstroemeria are cymes. Baby s breath is a
compound dichasium cyme.
What is an inflorescence and what are
the types of inflorescences?
l  2. A spike is an elongated inflorescence with
a central axis along which sessile flowers are
attached. Wheat, barley, ryegrass,
wheatgrass, gladioli, and liatris are spike
inflorescences.
l  3. A raceme is an elongated inflorescence
with a central axis along which are attached
simple pedicels of more or less equal length.
Examples of racemes include foxtail millet,
snapdragon, delphinium, Scotch broom, and
stock.
What is an inflorescence and what are
the types of inflorescences?
l  4. A panicle is an elongated inflorescence
with a central axis along which are
branches that are themselves branched.
Rice, oats, sudangrass, Kentucky
bluegrass, tall fescue, timothy, grain
sorghum, astilbe, and begonia have a
panicle inflorescence.
l  5. A corymb is a short and broad, flattopped indeterminate inflorescence having
a main vertical axis and pedicels or
branches of unequal length. The outer
flowers open first. Yarrow is an example of
a corymb.
What is an inflorescence and what are
the types of inflorescences?
l  6. An umbel is an inflorescence having several
branches arising from a common point.
u
u
u
a. A simple umbel consists of flowers with single pedicels.
b. Compound umbels have secondary branching in the form
of pedicels at the end of a ray.
c. Queen Anne s lace and amaryllis have umbels.
What is an inflorescence and what are
the types of inflorescences?
l  7. A spadix is a spike with a thickened,
fleshy axis, usually enveloped by a
showy bract called a spathe.
Floriculture crops with a spadix include
calla lily and anthurium.
l  8. A catkin is a spike, raceme, or cyme
composed of unisexual flowers without
petals and falling as a unit. Catkins are
found on willows, alders, oaks, and
birch.
What is an inflorescence and what are
the types of inflorescences?
l  9. A head is a rounded or flat-topped
cluster of sessile flowers. Head
inflorescences of the aster family
resemble single flowers. These consist
of centrally grouped flowers called disc
flowers encircled by ray flowers. Some
common plants that have a head
inflorescence are gerbera daisy,
chrysanthemum, sunflower, marigold,
dahlia, strawflowers, and cineraria.
REVIEW
l  1. What are the parts of a flower and their
functions?
l  2. What are the types of flowers?
l  3. What is an inflorescence and what are the
types of inflorescences?