Transcript Horticulture #1 - Horticulture Science

Horticulture Science
Lesson 6
Classifying Ornamental Plants
Interest Approach
Ask students to list as many plants as they possibly can
in two or five minutes. (An interesting side activity is to
ask them to list as many animals as possible in one
minute. Notice that many more animals are listed on
most student papers.) Begin a discussion on what types
of plants were listed. Are they monocots or dicots,
deciduous or evergreen, annual or perennial?
(With the side activity, are they mammals,
birds, reptiles, amphibians, or fish?)
Interest Approach cont.
Why do students know more animals than plants? Why
are students better able to classify animals than plants?
Is it because of parents’ lack of plant knowledge or
weaknesses in the educational system? Go around the
room from student to student asking each to name one
plant with which he or she is familiar. Immediately
classify each plant as a fern, gymnosperm,
or angiosperm (and whether each
angiosperm is a monocot or a dicot).
After each student has had a turn,
allow the class to make observations
as to which types of plants are the
most familiar and common.
Student Learning
Objectives
•Discuss the classification and
naming of plants.
•Distinguish the major groups of
plants.
•Contrast the classification of
plants by life cycle.
Terms
• angiosperms
• annuals
• biennials
• binomial nomenclature
• bryophytes
• conifer
• cotyledon
• cultivar
Terms
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deciduous
dicots
evergreen
ferns
genus
gymnosperms
herbaceous
monocots
Terms
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morphology
perennial
species
taxonomy
variety
vascular plants
How are plants classified and named?
• The branch of biology that deals with identifying
and naming organisms is taxonomy.
• Plants are classified based on the similarities of their
characteristics.
• Plant taxonomists compare flowering patterns, stem
and leaf structures, life cycles, genetic similarities,
and many other characteristics in determining which
plants are the most closely related.
• The study of the form or
shape of organisms or parts
of an organism is called
morphology.
How are plants classified and named?
• Taxonomists use categories to group the plants.
• The categories, from general to specific, are:
Kingdom, Division (Phylum), Class, Order, Family,
Genus, Species, Variety, and Cultivar.
• All plants are in the Kingdom Plantae. Vascular
plants (plants with tissue specialized for conducting
materials) are in the Division (Phylum) Tracheophyta.
How are plants classified and named?
• Plants are named using a system called binomial
nomenclature.
• This classification system was developed by
Carolus Linnaeus and uses Latin terms as scientific
names for plants.
Carolus Linnaeus, the
'father of modern
taxonomy'
How are plants classified and named?
• Even though each plant is given at least seven
names, it is commonly referred to by two scientific
names.
• The two names used for the scientific names of
plants are the Genus name, which is always
capitalized, and the species name, which is always
lower case (e.g., Liriodendron tulipifera).
Common Names for Liriodendron
tulipifera: Tuliptree, Tulip
Magnolia, Tulip Poplar, Yellow
Poplar, Whitewood
How are plants classified and named?
• The genus is a group of plants that are very similar
to each other.
• The species is a group of plants that are so similar
that they usually mate freely with each other in the
wild.
• Plants are also called by common names, but those
names are specific and are based on language and
geographic location.
How are plants classified and named?
• For instance, Liriodendron tulipifera is known in
the United States as the yellow poplar, tulip poplar,
tulip magnolia, whitewood, and tulip tree.
• Although the tulip tree may be known by many
common names in the United States, the plant is
recognized as Liriodendron tulipifera everywhere
on Earth.
How are plants classified and named?
• Sometimes cultivated plants within a species show a
significant difference from other plants in the species.
• These plants are called a variety. The difference is
inherited from the previous generation through sexual
reproduction.
• The variety is written in lower case, underlined or
italicized, and follows the specific epithet.
• A variety of Colorado spruce with bluish needles is
written as Picea pungens var. glauca or Picea
pungens glauca.
How are plants classified and named?
• Another group important to the horticulture
industry is cultivar.
• Cultivars have distinguishing characteristics
from the other plants in the species, but cultivars
do not transfer those characteristics to offspring
through sexual reproduction.
• Cultivars are propagated by
selective hybridization or asexual
means.
• A cultivar of red maple is written
as follows: Acer rubrum, also known
as “October Glory.”
What are some ways that we can put plants
into groups?
• The plant kingdom has become successful all over
the Earth by adapting to a wide variety of different
conditions and niches.
• The following are some of the major plant groups.
What are some ways that we can put plants
into groups?
• Bryophytes are plants that are classified in the
Phylum Bryophyta.
• These are nonvascular plants such as mosses and
liverworts.
• They tend to live in damp places and are very
limited in size due to the lack of conducting tissue.
What are some ways that we can put plants
into groups?
• Ferns are vascular plants that reproduce by
spores.
• Some people call them the amphibians of the
plant world because they are dependent on water
for their sperm to swim through during
reproduction.
• Ferns have no true leaves but have fronds, which
have a double purpose of food production and
spore formation.
• Fronds tend to unfold from the center
of the plant, causing the newest fronds
to be called “fiddlehead.”
What are some ways that we can put plants
into groups?
• Gymnosperms are plants that reproduce with seeds
that lay naked on scales.
• Most gymnosperms reproduce using a structure called
a cone.
• Any gymnosperm that reproduces by cone is called a
conifer.
• Examples include pines,
spruces, and cedars.
What are some ways that we can put plants
into groups?
• Conifer leaves are specialized to be either needles or
scales.
• Most conifers are evergreen, holding leaves all year.
• But some are
deciduous,
dropping leaves
in the winter.
•An example is the
bald cypress.
What are some ways that we can put plants
into groups?
• Angiosperms are seed plants whose seeds develop
within a fruiting body.
• Angiosperms all reproduce by flowers, although
many flowers are very small and not showy.
• So if any plant has flowers, it is in the Angiosperm
group.
• There are two types of Angiosperm.
What are some ways that we can put plants
into groups?
• Monocots are plants that have a single cotyledon or
seed piece.
• Monocots have flower parts in multiples of three,
parallel venation on their leaves, stems with
scattered vascular bundles, and narrow leaves.
• Examples include grasses, sweet corn, and lilies.
What are some ways that we can put plants
into groups?
• Dicots are plants with two cotyledons in their seeds.
• They have flower parts in multiples of four or five,
netted veins, and stems that are organized in a ring
pattern.
• They have broad leaves and include roses, petunias,
and geraniums.
What are
some ways
that we can
put plants
into groups?
How are plants classified by life cycle?
• Plants are often classified based on their life cycles.
• Gymnosperms and angiosperms reproduce by seed,
of course, but there are different strategies for
passing on that seed to future generations of plants.
How are plants classified by life cycle?
• Plants that complete their life cycle within one year
or one growing season are called annuals.
• Seeds of annuals germinate, produce leaves and
roots, flower, produce seed, and then die, all in less
than a year.
How are plants classified by life cycle?
• Many of our crops and garden plants are annuals.
• Corn, soybeans, rice, wheat, potatoes, and tomatoes
are examples of annual food crops.
• Petunias, impatiens, marigolds, and zinnias are
examples of garden annuals.
• Many plants that are considered weeds (i.e.,
ragweed, pigweed, lambsquarter, and crabgrass) are
annuals, too.
How are plants classified by life cycle?
• Biennials are plants that normally require two
growing seasons to produce flowers and seed before
dying.
• In the first growing season, biennials grow
vegetatively.
• In the fall, they go dormant and rest until the
following spring.
• During the winter months, they receive a required
cold treatment.
How are plants classified by life cycle?
• Growth is resumed in the spring of the second
season.
• The plants bolt, flower, produce seed, and die.
• This group of plants is fewer in number than the
other two groups.
• Some examples include hollyhock, Sweet William,
parsley, beets, and carrots.
How are plants classified by life cycle?
• Technically, a perennial is a plant that has a life
cycle of more than two growing seasons.
• It may take perennial plants a few years to many
years to reach reproductive maturity.
• Woody perennials may flower and produce seeds
every year for many years.
• They may be woody like trees and shrubs or
herbaceous.
How are plants classified by life cycle?
• The shoots of herbaceous perennials typically die
back to the ground each winter.
• The roots and crowns of herbaceous perennial
plants survive and send up new shoots in the spring.
• Strawberries and asparagus are herbaceous
perennials.
How are plants classified by life cycle?
• Woody perennial plants produce secondary growth
that persists year after year.
• Secondary growth gives the plants the ability to
grow in girth and height.
• During the winter months, they go dormant.
• Plant growth resumes in the spring.
• Examples of woody perennial plants include apples,
maples, oaks, almonds, and oranges.
How are plants classified by life cycle?
Review/Summary
•How are plants classified and
named?
•What are some ways that we can
put plants into groups?
•How are plants classified by life
cycle?