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Plant Classes and Parts
Basic Plant Science
AFNR-BAS-13: Explain and demonstrate basic plant science principles
including plant health, growth and reproduction.
Uses of Plants
 Plants provide for the three basic human needs:
1. food: fruits, vegetables, grains, nuts, etc.
2. clothing: cotton, linen, wool, leather (plants feed the
animals that grow the wool and leather)
3. shelter: lumber and other wood products
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Uses of Plants
 direct source: the plant or plant products are used
by humans
 fruits, nuts, vegetables, cotton
 indirect source: humans use the animal and animal
products that feed on plants and plant products
 beef, leather, chicken, wool
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Uses of Plants
 Plants are also used by humans for ornamental and
aesthetic reasons to provide comfort or beauty.
 landscaping (flowers, shrubs, trees, turf)
 ornamental horticulture and floral design (house
plants, cut flowers
 forestry and outdoor recreation (wildlife habitat,
hiking, hunting)
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Major Groups of Plants
 gymnosperms:
 means “naked seed” in Greek
 plants that produce seeds not protected by fruit
 examples: pines, firs, spruces, redwoods, ginkgo
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Major Groups of Plants
 angiosperms:
 in Greek means “covered seed” or “enclosed seed”
 plants that flower and produce seeds protected by
fruit or pods
 examples: apples, peaches, pecans, soybeans
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Major Groups of Plants
 There are two classes of angiosperms with distinct
characteristics.
 cotyledon: an embryonic leaf which become the seed
leaf
 monocotyledons (a.k.a. monocots); “mono-” - means
“one”
 dicotyledons (a.k.a. dicots); “di-” means “two”
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Major Groups of Plants
 monocotyledons (a.k.a. monocots)
 seeds have one cotyledon therefore the seedlings have
one seed leaf
 the vascular bundles are scattered
 the leaves have parallel veins
 flower parts are in multiples of three
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Major Groups of Plants
 dicotyledons (a.k.a. dicots)
 seeds have two cotyledons therefore the seedlings have
two seed leaves
 the vascular bundles are arranged in a circle
 the leaves have netted veins
 flower parts are in multiples of four or five
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Taxonomy (Naming
Plants)
 scientific names are in Latin and printed in italics
 common names can be confusing because different
areas call plants by different names
 binomial nomenclature
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two-name system
first name is the genus
second name is the species
species can be further subdivided into varieties
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Plant Life Cycles
 Annuals: plants that complete their life cycle in one
year (or one season)
 examples: marigolds, pansies, petunias, melons,
beans, squash (and many other flowers, crops, and
weeds)
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Plant Life Cycles
 Biennials: plants that complete their life cycle in two
growing seasons
 grows vegetative structures (roots, stems, leaves) in
the first year and then after a period of dormancy
during cold months, it will produce flowers and
seeds before dying
 examples: carrot, parsley, onion, cabbage,
hollyhock, Black-eyed Susan
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Plant Life Cycles
 Perennials: plants that produce for more than two years
or growing seasons
 may die back during the winter months and then return
from their rootstock
 examples: azalea, alfalfa, pine trees, maple trees, fruit
and nut trees, blueberries
 There are two classes of perennials.
 herbaceous: plants that have soft stems that are killed by
frost
 woody: plants with hardy stems that can survive winter
frost
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Plant Processes
 photosynthesis: the chemical process converting
sunlight into energy and food for the plant
 respiration: the process of plants using stored
energy
 transpiration: the movement and loss of water
through evaporation
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Plant Parts
 Roots:
 anchor the plant
 absorb water and minerals
 store manufactured food
 primary root: the single main root
 secondary roots: small roots that branch off the main
root
 root hairs: many tiny roots that increase the surface area
of the root for absorption
 root cap: protects the growing tip of roots
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Plant Parts
 Types of Roots:
 tap root: root system with one thick main root
 fibrous roots: system with many small roots
 adventitious roots: grow from the stem or leaf of a
plant
 example: corn has roots above ground to prop up the
stalk
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Plant Parts
 Stems:
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support the leaves, flowers, and fruit
conduct water, minerals, and food
store food and water
produce new stem tissues
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Plant Parts
 Two types of conductive tissues in the stem:
 xylem: transports water and minerals from the roots
 phloem: transports food from the leaves
 both are created by the cambium which becomes
growth rings in trees
 the xylem and phloem are arranged in a ring in dicots
and scattered in moncots
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Plant Parts
 Leaves:
produce food for the plant through photosynthesis
epidermis: protective layer of cells
cuticle: waxy coating that prevents water loss
stomata: pore-like openings on the underside of the leaf
that allow gas exchange
 guard cells: control the opening and closing of the stomata
 mesophyll: where photosynthesis takes place; made up of
palisade layer and the spongy layer
 veins: contain xylem and phloem and transport water and
nutrients
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Plant Parts
 Flowers:
 purpose of flowers is to reproduce through the
production of seeds
 sepals: the outermost part of a flower (usually green)
that protects the unopened flower and supports the
petals when it blooms
 as a whole all the sepals are called the calyx
 petals: attract insects and birds for pollination; usually
conspicuously colored
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Plant Parts
 Flowers:
 stamen: the male part of the flower
 anther: produces the pollen which contains the male sex
cells
 filament: supports the anther
 pistil: the female part of the flower
 stigma: provides a sticky surface to catch pollen
 style: supports the stigma
 ovary: produces the female sex cells and becomes the
fruit
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Flower Anatomy
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Plant Parts
 Flowers:
 complete flowers: flowers that have all the parts
(sepals, petals, stamen, and pistil)
 incomplete flowers: flowers that lack one of the four
main parts - petals, sepals, pistil, or stamen
 male flowers will not have a pistil and female flowers
will lack stamen
 monoecious: plants that have male and female flowers
on the same plant
 dioecious: plants that have male and female flowers
on separate plants
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Plant Parts
 Fruit:
 a mature (fertilized) ovary containing the seed or
seeds
 may be fleshy or dried
 fleshy fruit are soft and may be consumed by humans or
animals as food which helps to disperse the seeds;
examples include pumpkin, apple, tomato
 dry fruits have hard seeds
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