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Plant Names and
Classifications
Plant
Classification
Grouping plants by their similar
characteristics
Plant Taxonomy
Taxonomy = Classification
Scientific Classification
Binomial Nomenclature (2 names)
Latin - Never changes, a universal language
Developed by Carolus Linnaeus
Circumstances have dictated the necessity of
distinguishing among 10 million types of
organisms, as well as those that have become
extinct, in a manner that will identify them
anywhere, regardless of the language spoken
locally.
At present all living organisms are given a single
two-part Latin scientific name, and mostly also have
applied to all individuals of a specific kind of
organisms, no matter where they may be found, but
many common names may be given to the same
organism, and one common name may be applied to
a number of different organisms.
In Europe, with its many languages, common names can
become very numerous indeed. The widespread weed with
the scientific name Plantago major, for example, is often
called broad-leaved plantain in English, but also has no
fewer than 45 other English names, 11 French names, 75
Dutch names, 106 German names,
Plantago major,
and possibly as many as several hundred more names
in other languages, with literally dozens of these
names also applying to quite different plants.
If it were not for the early recognition by biologists
in naming and classifying all organisms, utter chaos
eventually might have prevailed in communications
concerning them.
Development of the binomial system of nomenclature
The first person of note attempt to organize and classify
plants was Theophrastus.
His third century B.C. classification of nearly 500
plants into trees, shrubs, and herbs, along with his
distinction plants on the basis of leaf characteristic, was
used for hundreds of years
It was not until the thirteen century A.D. that a
distinction was made between monocots and dicots
on the basis of stem structure.
After this, herbalists added considerably to
Theophrastus list, and by the beginning of
eighteenth century, details of fruit and flower
structure were utilized in classification scheme in
addition to form and habit.
All organisms were grouped into genera (singular:
genus), with the first word of the Latin phrase
indicating the particular genus to which organisms
belonged. For example, all known mints were given
phrase names beginning with the word Mentha, the
name of the genus. Likewise the phrase of Lupinus
began with Lupinus.
At this point, the Swedish botanist, Carolus Linnaeus
(1707-1778), began improving the way the
organisms were named and classified, and the
system he established worked so well that it has
persisted to the present.
When Linnaeus began his work, he set out to classify
all known plants and animals according to their
genera. He limited each Latin phrase to a maximum of
12 words and in the margin next to the phrase he listed
a single word, which when combined with the generic
name, formed a convenient abbreviated designation for
species. The word for spearmint was spicata.
Linnaeus and those who followed him eventually
replaced all the phrase names with abbreviated one.
Because of their two parts, these names became
known as Binomial System of Nomenclature.
Today all organisms are named according to this
system, which in current use also includes the
authority for the name, either in abbreviated form or
in full, after the Latin name.
Thus the full scientific name for spearmint is now
written Mentha spicata L., the L standing for
Linnaeus, and the full scientific name for the
common dandelion is written Taraxacum officinals
Wiggers, because F.H. Wiggers was the first who
described the species.
Taraxacum officinals Wiggers,
Development of the Kingdom Concept
When classification schemes were first developed,
all living organisms were placed in either the Plant
kingdom or the Animal kingdom. Many microscopic
organisms have characteristic of both plants and
animals, however and in the 1860 Hogg and
Haeckel proposed a third kingdom (Protista) for all
organisms that did not develop complex tissues.
In 1939, H.F. Copeland divided the Protista into two
kingdoms, with organisms have prokaryotic cell
placed in the Kingdom Monera, and those with
eukaryotic cells being left in the Kingdom
Protoctista or Protista.
Comparison Between Prokaryotic and Eukaryotic Cells
Characteristic Prokaryotes Eukaryotes
Size of cell Typically 0.2-2.0 m m in diameter Typically 10-100 m m in diameter
Nucleus No nuclear membrane or nucleoli (nucleoid) True nucleus, consisting of nuclear membrane &
nucleoli
Membrane-
enclosed
organelles
Absent Present; examples include lysosomes, Golgi
complex, endoplasmic reticulum, mitochondria &
chloroplasts
Flagella Consist of two protein building blocks Complex; consist of multiple microtubules
Glycocalyx Present as a capsule or slime layer Present in some cells that lack a cell wall
Cell wall Usually present; chemically complex (typical
bacterial cell wall includes peptidoglycan)
When present, chemically simple
Plasma
membrane
No carbohydrates and generally lacks sterols Sterols and carbohydrates that serve as receptors
present
Cytoplasm No cytoskeleton or cytoplasmic streaming Cytoskeleton; cytoplasmic streaming
Ribosomes Smaller size (70S) Larger size (80S)
Chromosome
(DNA)
arrangement
Single circular chromosome; lacks histones Multiple linear chromosomes with histones
Cell division Binary fission Mitosis
Sexual
reproduction
No meiosis; transfer of DNA fragments only
(conjugation)
Involves meiosis
Since there are differences in the mode of nutrition
of organisms in Copeland’s Kingdom Protoctista,
many biologists now favor five kingdoms, as
proposed by R.H. Whittaker in 1969. In Whittaker’s
system, there are three kingdoms based on forms
of nutrition (photosynthetic, ingestion of food,
absorption of food solutions) and two kingdom of
protesta based on differences in cellular structure.
Slime modes, which have no cell walls at certain
stages and do have walls at others, still do not fit
well into the five-kingdom system, but this system
appears to be the most satisfactory arrangement so
far proposed.
Scientific Classification
Animalia Planta Protista
Monera Fungi
Kingdom
Classification of Major groups
Since Linnaeus time, a number of classification
categories have been added between the levels of
kingdom and genus. Genera are now grouped into
divisions, and divisions into kingdoms. Depending
on which system of classification is used, there may
be between 12 and 30 divisions of plants recognized.
The following is a classification of major groups of
living organisms utilizing a modification of Wittaker’s
five-kingdom system.
If we are to give a complete classification of an onion
according to this particular arrangement, it would look
like this;
It is customary to give binomials in italics (or to
underline the words).
Scientific Classification
KingdomDivision (Phylum)
Class
Subclass
Order
Family
Genus
Species
Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Liliopsida – Monocotyledons
Subclass Liliidae
Order Liliales
Family Liliaceae – Lily family
Genus Allium cepa L. – onion
Species: A population of individuals capable of
interbreeding in nature but not generally
interbreeding with members of another species.
Kingdom Protista
Kingdom Protista includes organisms that all have
eukaryotic cells but are otherwise diverse. Members
may be unicellular or multicellular, and occurs as
either colonies or filament. Modes of nutrition
includes photosynthesis, ingestion of food, and
absorption of food in solutions. Some are nonmotile
but most are motile by means of flagella or by
amoeboid movement.
Division Chrysophyta -
The Golden-brown algae
The golden-brown algae are grouped into four
classes that include:
the yellow-green algae, the true golden-brown algae,
the diatoms, and the cryptophytes.
Diatoms
Diatoms, which have a glassy shell that consist of two
“halves” that fit together like a pillbox, are extremely
abundant, particularly in colder marine waters.
The shells are usually etched with fine grooves and pores
through which the cytoplasm is in contact with the
environment.
Kingdom Protista
SubKingdom Phycobionta - Algae
Division Chrysophyta –
The Golden – Brown Algae
Diatoms
Diatoms are often golden-brown in color due to the
presence of the brownish pigment fucoxanthin in the
one to many chloroplasts occurring in each cell.
Diatoms move in caterpillar fashion by contact of the
cytoplasm with a surface as it protrudes through the
pores.
In asexual reproduction, the two “halves” of a cell
separate after mitosis of the protoplast, and a new
half forms within each original portion.
An auxospore (zygote) is produced through a sexual
process involving the fusion of gametes.
Division Euglenophyta-
The Euglenoids
The euglenoids have no rigid cell wall, only one
functional flagellum, a gullet, and a carbohydrate
food reserve called paramylon. Reproduction is by
cell division.
Sexual reproduction has not been confirmed.
Euglena
Euglena cell, which is spindle-shaped, can be seen to
change shape even as the organism moves along. Just
beneath the plasma membrane are fine strips that
spiral around the cell parallel to one another. The
strips and the plasma are devoid cellulose and
together are called a pellicle.
Division Euglenophyta –
The Euglenoids
A single functional flagellum, which has numerous
tiny hairs along one side, pulls the cell through the
water. A second very short flagellum is present
within a reservoir at the base of the functional
flagellum. There is a gullet or groove, through which
food can be ingested. A red eyespot is located in the
cytoplasm near the base of the flagella.
Reproduction is by cell division, starts to divide at
the flagella end and eventually split lengthwise, to
form two complete cells.
Division Chlorophyta-
The Green algae
Occur in wide variety of aquatic habitats. Their cells
have the same pigments and reserve food (starch) as
those of higher plants.
Chlamydomonas
Unicellular green algae, has a pair of flagella that
enable the cell to move rapidly. Within the cell, there
is a chloroplast containing one or two pyrenoids, two
or more vacuoles, and often a red eyespot.
Asexual reproduction is by mitosis, sexual
reproduction is by union of like gametes.
Division Chlorophyta-
The Green Algae
Chlamdomonas
Spirogyra
Spirogyra is a floating, filament green algae with
spiral, ribbonlike chloroplasts. It does not produce
flagellated cells of any kind. Asexual reproduction is
by fragmentation (breaking of filaments with each
fragment adding new cells by mitosis). Sexual
reproduction is by conjugation.
Spirogyra
A- A portion of a vegetative filament; B-
D Sexual Reproduction
Other green algae
Other green algae include Chlorella, a tiny
unicellular alga that ease to culture and has been used
in experiments to produce oxygen for space vehicles;
Acetabularia which produces huge mushroom like
cell. Volvox is a colonial alga that forms motile
hollow balls of hundred to thousands of cells; Sea
lettuce (Ulva) has blades that anchored to rocks by
means of holdfast.
Other Green Algae
ChlorellaVolvox
Division Phaeophyta-
The Brown algae
The brown algae include the largest seaweed. Many
are differentiated into a stalk (stripe), flattened blades
and a tough, sinewy that holds the seaweed to the
rocks. Fucoxanthin is largely responsible for the
color brown algae whose main carbohydrate food is
laminarin. Some produce algin (alginic acid), a
useful gelatinous substance.
Division phaeophyta –
The Brown Algae
Nereocystis, a
kelp
Sargassum,
a floating brown algae
Division Rhodophyta-
The Red Algae
Red algae tend to be smaller than those of the brown
algae, have relatively complex live cycle. The color
of red algae are partially due to the presence of red
and blue phycobilins.
Division Rhodophyta –
The Red Algae
Human Relevance of Algae
Algae are important in aquatic food chains and in
numerous other ways.
Diatom shells have accumulated for thousand of
years on ocean floors and make up diatomaceous
earth that is used for filtering, polishes, insulation
and reflectorized paint.
Chlorella is a potentially important food and oxygen
source. Future spacecraft may be equipped with
tanks of such algae.
Algin is used as stabilizer and thickening agent in
hundreds of food products, paints, medicines, papers,
ceramic and others.
Brown algae are a source of fertilizer and iodine and
some serve as food for both of livestock and humans.
Red algae are a source of agar, which is used as
cultural medium for bacteria and other organisms or
tissues; some are also used for human food.
Plant Classes
Tracheophyta
Gymnosperms Angiosperms
Plant Order
Angiosperms
Subclasses
Monocotyledon Dicotyledon
Seed Plants Tracheophyta
Division Pinophyta
Gymenosperms
The name gymnosperm is derived from two Greek
words gymnos, meaning naked, and sperma, a seed.
The name refers to the exposed nature of seeds,
which are produced on the surface of sporophylls or
similar structures instead of being enclosed within a
fruit as they usually are in the flowering plants.
Seed
Plants
Gymnosperms
The seed-bearing sporophylls are often spirally
arranged in female strobili (cones), which develop on
the sporophyte along with smaller male strobili that
produce pollen grains.
The female gametophyte within an ovule containing
a fleshy, nutritive diploid nucellus that is itself
enclosed within one or more outer layers of diploid
tissue.
These outer layers of tissues constitute an
integuments, which become a seed coat after the
fertilization and development of an embryo occurred.
The division Pinophyta, which includes all living
gymnosperms, is divided into three subdivisions.
Cycadicae includes the superficially palm like
cycade, which produce their seeds in cones,
Pinicae includes the Conifers and Ginkgo,
Gnetica includes three genera of genophytes.
Conifers constitute the largest and most significant
group by far, totaling some 575 species. Pines,
spruces, hemlocks, redwoods, cedars and others
belong to this class.
Fossils of some conifers extend back 290 million
year to the late carboniferous period.
Division Pinophyta, Class Pinatae
The conifers
Pines:
The largest genus of conifers, Pinus (pines) has over
100 living species. They are the predominant trees in
the vast coniferous forests of the Northen
Hemisphere. They have also been planted
extensively in the Southern Hemisphere. They
include the world’s oldest known living organisms.
Division Pinophyta, CalssPinatae- The Conifers
Reproduction
Microspores occur in microsporangia that develop in
pairs toward the basis of papery or membranous scales
arranged in a spiral or whorls around an axis, forming a
strobilus or male cone.
Male cones which are usually produced in the spring in
clusters of up to 50 or more toward the tips of the lower
branches, are commonly not more than 1-4 cm. They
become shriveled and spent within a few weeks and then
fall from the trees, after the pollen has been released.
Microspore mother cells in the microsporangia each
undergo meiosis, producing the four haploid
microspores. These then develop into pollen grains,
each consisting of four cells and a pair of external air
sacs.
Megaspores are produced in megasporangia
located within ovules at the base of the female cone
scales.
The female cones (or strobili), are much larger than
the male cones. When they mature they have woody
scales, with inconspicuous bracts between them,
arranged in spiral around the axis.
They are produced on the upper branches of the same
tree on which the male cones appear. The ovules occur
in pairs toward the base of each scale of the immature
cones. Each ovule contains a megasporangium within
multicelluar nutritive tissue called the nucellus, which
in turn, enclosed by a thick, layered integuments. The
integuments has a channel or pore called a micropyle.
One of the integuments layers later becomes the seed
coat of the seed.
A single megasporangium of each ovule undergoes
meiosis, producing a row of relatively large
megaspores. All except one of the megaspores soon
degenerate. The remaining one slowly develops over
a period of month into a female gametophyte.
Toward the end of the gametophyte development,
two to six archegonia become differentiated at the
end facing the micropyle.
Each archegonium contains a single large egg.
Female cones, which are usually reddish at first,
commonly take two seasons to mature into green and
finally the brownish woody structure that are
familiar.
During the first spring, the immature, radish cone
scales spread apart, and pollen grains carried by the
wind shift down between the scales. There they catch
in sticky drops of fluid oozing out of the micropyles.
As the fluid evaporates, the pollen is drawn down
through the micropyle to the top of nucellus.
After pollination, the scales grow together and
close, protecting the developing ovule.
The female gametophyte is not mature with
archegonia for more than a year after that.
Meanwhile the pollen grain (immature male
gametophyte) forms an outgrowth called a pollen
tube, which slowly digests its way through the
nucellus to the area where the archegonia develop.
While the pollen grains enter it.
One of these called the generative cell divides and
forms two more cells, called the sterile cell and the
spermatogenous cell.
The latter divides again, producing two male
gametes, or sperms.
This germinated pollen grain, with its pollen tube
and two sperms, constitute the mature male
gametophyte.
About 15 months after pollination the pollen tube
reaches the now present archegonium. One sperm
unites with the egg, forming a zygote, the other
sperm and remaining cells of the pollen grain
degenerate.
The zygote begins to develop into an embryo. At a
later stage, an embryo may divide in such a way as
to produce the equivalent of identical twins.
Normally one embryo completes development.
While this development is occurring one of the layers
of the integuments hardens, becoming a seed coat. A
thin membranous layer of the cone scale becomes a
“wing” on each seed, which aids in the seed’s
dispersal.
Subdivision Cycadicae – The cycads
Cycads are slow-growing plants of the tropics and
subtropics that look like a cross between a tree fern
and a palm.
They have unbranched trunks that grow to more than
15 meters tall in a few species with a crown of large
pinnately divided leaves.
Several of the approximately 100 known living
species are presently facing extinction.
Their life cycle are similar to conifers. Cycads are
dioecious, the male and female strobili, which are
sometimes massive, being produced on separate
plants.
The scale of female strobili of some species are
covered with feltlike or wooly hairs and grow to as
much as 1 meter long.
Subdivision
Cycadicae- The Cycads
AB