Senin, 06 Desember 2010

kasifikasi taksonomi

1

Introduction to Plant

Classification

Why Classify Plants?

• Why classify or group anything?

– Because that’s what we do

– We put spoons with spoons so we can find

them
– We match our socks and put them in the
sock drawer
– We invented time so everything doesn’t
happen at once
– How do you organize your CD collection?
How many Species?
• South America 98,800
• North America 23,000
• Central America 7,380
• Tropical Central Africa 16,032
• East Africa 7,850
• Europe-Mediterranean Basin 19,236
• Temperate Asia 61,680
• Australia 25,000
• Estimate of between 250,00 and 420,000
• http://www.plant-talk.org/stories/28bramw.html
Plant Systematics
• “Taxonomy” and “systematics” are
largely synonymous, but “systematics”
implies the study of evolutionary
relationships
• Taxonomy is the science of
classification, especially the
classification of biological organisms
A little History
• Preliterate
• Ancient literate
• Medieval or dark ages
• Renaissance
• Theory of Evolution
Preliterate
• Most cultures figured out what plants were
beneficial and which were not whether for
medicines, food, clothing, shelter, weapons
• Cave drawing showed us how plants were used
• In most cultures the medicinal aspects of plants
were closely guarded secrets and probably
passed on from medicine man to medicine man.
In almost all cultures, even today, medicinal
information is concentrated in the hands of a few,
whether it be witch doctors, medicine men,
shamans or even doctors2
Ancient literate - Greeks
• Theophrastos (ca. 300 BC). The father of
botany, student of Aristotle. Wrote over 200
“articles” including Historia plantarum which is
considered to be the first botany book
– Several of his observations and contributions
include:
• classification into trees, shrubs, subshrubs and herbs
• distinction between flowering vs. non-flowering plants
• recognition of different kinds of sexual & asexual
reproduction
• Tissues organs, recognition of the fruit as a pericarp
Ancient literate - Romans
• Pliny the Elder 23-79 A.D. wrote Historia
Naturalis a series of 37 books where he
describes over 1000 plants and included
medicinal properties, economic uses, cultural
requirements
• Dioscorides - Physician of Greek ancestry,
served in the Roman Army.
– Wrote one of the oldest surviving and most
influential natural history books ever written,
Materia Medica. It was an account of plants of
medicinal value. Until the Renaissance (1500's)
this was the reference work.
Others
• Chinese literature
– Medical-botanical treatises. Chinese mastered
printing some 400 years before Europeans.
• One famous version is called Chen lei pen ts’ao printed
in 1108 AD
• Ancient India
– Vrikshayurveda is a botanical book written prior to
the Christian era. Botany, morphology and
classification
• Aztecs
• Medical-botany book written by 2 Aztec Indians in 1552
Medieval or Dark Ages
• Collapse of Rome brought on the Dark
Ages
• Not much scientific research
• Most interested in surviving, little time
for inquiry
• Some monks wrote about growing
herbs at their monasteries
Renaissance
• Tremendous advances in science, two
of which are very important in plant
sciences
– printing press
– science of navigation
Herbalists
• 1500's. Motivated by practical
considerations, i.e. medical and agricultural
uses of plants.
• No real systems of classification but marked
period of original work rather than copying the
ancients work.
• Based on first hand observations by the
authors and provided detailed and accurate
description of the plants of medicinal use.
• Several prominent Germans: Brunfels,
Bock, Fuchs (Fuchsia).3
Doctrine of Signatures
• The idea (Jakob Bohme
1575-1624) that God
marked everything he
created with a signature.
• The Doctrine states that,
by observation, one can
determine from the color
of the flowers or roots,
the shape of the leaves,
the place of growing, or
other signatures, what the
plant's purpose was
Doctrine of Signatures
• Lung wort, due to the spots on its leaves was
related to Pulmonary complaints
• Hepatica was used for liver problems
• Plants with yellow flowers or roots, such as
Goldenrod were believed to cure conditions of
Jaundice by the signature of color
• Plants with a red signature were used for
blood disorders
• Quaking Aspen leaves were used for shaking
Palsy
• Maidenhair fern cured baldness
Transition Period
• Introduction of so many plants and the
exchange of literature resulted in an
obvious need to develop a system
• Terminology became more descriptive,
plants were grouped into families and
genera, plant sexuality became known
• Plant names were descriptive phrases,
Acer orientalis hederae folio
Transition Period
• John Ray
– Englishman in 1703
published Methodus
Plantarum in which he
described 18,000
species. His “natural”
classification system
grouped plants that
looked alike.
– He used characteristics
such as growth habit,
woody vs herbaceous,
monocots vs dicots as
well as leaf and flower
characteristics.
Carolus Linnaeus
• A Swedish physician, is
considered the father of
plant taxonomy
• Developed a sexual
system of classification
which was based on the
numbers of
reproductive parts.
Purely artificial groups
but easy to use
• Funny guy, was so
taken by Latin he
“latinized” his own
name (Carl von Linne`)
Linnaeus’s System
• The sexual basis of Linnaeus's plant
classification was controversial in its day;
although easy to learn and use, it clearly did
not give good results in many cases. Some
critics also attacked it for its sexually explicit
nature: one opponent, botanist Johann
Siegesbeck, called it "loathsome harlotry".
• Linnaeus had his revenge, however; he
named a small, useless European weed
Siegesbeckia.4
Linnaeus
• Major contribution was he developed a short
hand system (2 words or binomial) that used
to have up to 10 words.
– Acer palmatum was Acer orientalis hederae folio
– Dianthus caryophyllus was Dianthus foroibus
solitariis,squamis,calycinis,subobovatis,
brevissimus,corollis,crenatis
• Lucky for you and me things changed!
• Species Plantarum (1753) is the starting point
for modern taxonomy, not just plants but
animals as well
Natural Systems
• Botanist by late 1700’s began to ponder the
purposes of taxonomy and tried to provide
more information content in their
classifications, i.e. they wanted to reflect
"natural relationships".
• Although Linnaeus had provided a convenient
method for identifying plants, it was clearly
artificial, e.g. Cacti and pines were classified
together because they had numerous male
parts.
Natural Systems
• Placing species in groups because of
characteristics shared, correlated and in
common as opposed to differences.
• The systems were designed to show
similarities not differences
• Lots of work was done in botanical gardens
while attempting to plant “groups” of plants
that represented a natural group
Origin of the Species
• Charles Darwin’s monumental work, On the
Origin of Species made the concept of
organic evolution academically respectable.
• The Darwin-Wallace theory of evolution
including being modernized by the inclusion
of genetic theory has stood the test of time.
• Virtually all scientists accept
– gradual change in the nature of life
– populations of organisms that are in constant flux
Engler - Prantl
• Following Darwins lead they developed Die
naturichen Pflanzenfamilien between 1887
and 1915.
• What was significant was that the groups
were arranged within the plant kingdom from
the simplest plants to the structurally
complex.
– Salicaceae were simple (flowers with the simplest
structure where the flower structure of the
Asteraceae is complex.
Phylogeny
• The evolutionary history of a taxon, an attempt to
account for it’s origin and development
• C.E. Bessey (1845-1915). Professor at the Univ
of Nebraska
• Developed a set of “dicta” that suggested what
features were “primitive” and which were
“advanced”. Primitive being found in the most
ancient plants and advanced being found in the
most recently evolved
• Simple (Engler-Prantl) could be a result of
reduction and thus be advanced5
Objectives
• To develop a system
where like plants are
grouped together to
show how plants are
related and how
they have evolved
from common
ancestors