Order from Chaos
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Life can only be
understood backwards;
but it must be lived
forwards.
Soren Aabye Kierkegaard
Classification Historical Review
The
Relationships
of Plants
Plants
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Organisms supplied with chlorophyll, capable
of trapping the radiant energy of sunlight,
transforming it into stored potential energy
while at the same time releasing oxygen to
the atmosphere.
An assemblage of organisms lacking
chlorophyll but morphologically very similar
to certain groups of the lower plants supplied
with chlorophyll.
So Many, Many Plants
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We know that there are hundreds of
thousands of different plants inhabiting this
world.
We know that there is a structured order to
how these plants are grouped together.
How did this happen?
Classification
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Any classification is the placing of similar
things together.
The problem in biological classification is the
meaning of the word SIMILAR.
Classification Expectations
1)
2)
3)
4)
5)
Easy to use
Stable
An aid to memory
Predictive
Concise
Throughout history,
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Scientists have tried to determine the best
way to classify plants.
Ideas on how to do this have changed
considerably over time.
Understanding plant classification means
that we have to understand its history.
When did it start?
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We can only speculate
when humanity first
started to classify
plants.
Historians of botany
generally begin the
history of botanical
classification with folk
taxonomy.
Folk Taxonomy
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Folk biological classification is the way rural or
indigenous peoples make sense of and organize
their natural surroundings (the world around them,)
typically making generous use of descriptors like
bushes, bugs, ducks, and the likes.
Folk taxonomies are generated from social
knowledge and are used in everyday speech. They
are distinguished from scientific taxonomies that
claim to be disembodied from social relations and
thus objective and universal.
Disembodied from social relations???
Maybe…maybe not!
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Ambrosia trifida L. (aka Ragweed)
Ragweeds are rank-smelling (to some)
plants that uglify (beautify?) waste places in
late summer. Linnaeus invented the genus
Ambrosia which means ‘food of the gods’ to
describe them. Did he picture generations of
botanists and gardeners smiling at his joke?
History of Plant Systematics
Aristotle and pal Theo?
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One of you in the future?
The history of plant systematics as a science (organized
biological classification of plants) stretches from the work of
ancient Greek to modern evolutionary biologists.
Historia Plantarum
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Historia Plantarum, by Theophrastus, is the earliest
surviving treatise on plants. The work served as a
reference point in botany for many centuries.
Historia Plantarum was organized in ten books, and
is an encyclopedia of the plant kingdom, in which a
draft taxonomy is sketched with a basic classification
of plant "elements".
Theophrastus did not articulate a formal
classification scheme; instead he relied on the
common groupings of folklore combined with growth
form: tree, shrub, sub-shrub, herb.
Theophrastus Who???
(could he really have lived for 116 years?)
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Theophrastus (371 – c. 287 BC), was a student and
eventually the successor of Aristotle in the
Peripatetic school, a school of philosophy in ancient
Greece founded by Aristotle.
His two surviving botanical works, Enquiry into
Plants and On the Causes of Plants, were an
important influence on medieval science.
On the strength of these works, some call him the
"father of taxonomy".
The Science of Plant Systematics
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As a field of science, plant systematics came into
being only slowly, early plant lore usually being
treated as part of the study of medicine.
Later, classification and description was driven by
how scientists of the time understood nature. Until
the advent of Darwin’s theory of evolution, nearly all
classification was based on the scala naturae.
Botany’s elevation to a professional science in the
18th and 19th century marked a shift toward more
holistic classification methods, eventually based on
evolutionary relationships.
Scala Naturae What???
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The great chain of being or scala naturae is a
classical and western medieval conception of the
order of the universe, whose chief characteristic is a
strict hierarchical system.
The chain of being is composed of a great number of
hierarchical links, from the most basic and
foundational elements up through the very highest
perfection, in other words, God.
Rudbeckia hirta
Black-eyed Susan
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Kingdom Plantae – Plants
Subkingdom Tracheobionta – Vascular plants
Superdivision Spermatophyta – Seed plants
Division Magnoliophyta – Flowering plants
Class Magnoliopsida – Dicotyledons (Eudicots now)
Subclass Asteridae
Order Asterales
Family Asteraceae – Aster family
Genus Rudbeckia – coneflower
Species Rudbeckia hirta – black-eyed Susan
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Source: USDA and the Great Chain of Being…
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Carolus Linnaeus
syn Karl Linn
syn Carl von Linne
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Classification was a
complex and strange
thing before Linnaeus
developed his
system, and became
even stranger and
more complex after.
Linnaeus
Linnaeus Methodology
By combining the binomial method with
his (originally) simple method of counting
stamens, Linnaeus created a working
system of classification that became
widely embraced, as it proved on the
whole, to be much more practical and
flexible than any previous method
devised.
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Genus and species
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The genus name indicates a group of similar
plants and renders unnecessary a great deal
of description because all members of a
genus share certain details of structure.
The species name specifies one kind of plant
within that genus, and often adds unique
identifying information such as leaf shape,
flower color, or how the plant is used.
The future is not what it used to be
(aka when Linneaus worked out his classification scheme. )
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Darwin’s publication of On the Origin of
Species was more than a hundred years in
the future.
Geologists were not yet appreciating the
antiquity of Earth.
Paleontology had yet to be born.
Extinction was unknown. No dinosaur bone
had yet been recognized.
Question
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How do you think Linneaus would have
replied to the notion that extant species have
evolved from previous, now extinct, species?
1) Ya sure ya betcha
2) “There are now as many species as the
infinite being created diverse forms in the
beginning.”
Who was the zillion-times
great-grandma (pa)
of all living things?
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Linnaeus didn’t have to trouble himself about
that question. In his day, the division between
the plant and animal kingdoms was to him
and his contemporaries manifest from the
instant of Creation, when every species had
been given life simultaneously, and since
when all had remained unchanged.
Taxonomy Today
Attempts to encode each organism’s place
within evolutionary history.
 As more of that history becomes known, and
as sophisticated technology allows a more
penetrating study of both living and fossil
plants, quite a few plants once named on
gratuitous resemblances have been renamed
to reflect their genealogy.
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Evolution Solution?
The complete classification of an organism is
its evolutionary address.
 Each step up the hierarchy is a step back in
time.
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Evolutionary Theory
Monerans to Protistans Perhaps?
Those most primitive organisms, the ones
whose kind appear to have arisen earliest in
the course of evolution are unicellular
Monerans, the prokaryotes, bacteria, and
cyanobacteria
 The Protistans, a noncommittal name for
unicellular or communal eukaryotes that
means ‘the first’ without specifying animal,
vegetable, or fungal.
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Onward Protistans Soldiers
You Are How You Eat
Those that tend to feed their needs like
PLANTS by photosynthesis.
 Those that tend to digest like FUNGI outside
their bodies.
 Those that tend to ingest food like ANIMALS.
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Notables to Remember
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Cesalpino, Andrea (1519-1603)
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(aka Andreas Caesalpinus)
Italian botanist who showed that plants could be and
should be classified by their anatomy and structure.
In De plantis(1583) Cesalpino offered the first
remotely modern classification of plants. Before this
plants were classed by their location - for example
marsh plants, moorland plants, and even foreign
plants.
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Notables to Remember
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Joseph Pitton De Tournefort (1656-1708)
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A French botanist, notable as the first to make a clear definition of the
concept of genus for plants.
His principal work was the 1694 Eléments de botanique, ou Méthode
pour reconnaître les Plantes
The work's most important contribution was a clear distinction between
genus and species. With the concept of the genus, Tournefort was
able to cluster the 7,000 plant species he described into 700-plus
genera, making classification easier, and preparing the way for
Linnaeus. Linnaeus used many of the genus names and descriptions
as defined by Tournefort.
The word “herbarium" also seems to have been an invention of
Tournefort; previously herbaria had been called by a variety of names.
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Notables to Remember
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Carolus Linnaeus (1707-1778)
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A Swedish botanist, physician and zoologist, who is known as
the father of modern taxonomy.
His father adopted the Latin-form name Linnaeus after a giant
linden tree on the family homestead.
Linnaeus's main contribution to taxonomy was to establish
conventions for the naming of living organisms that became
universally accepted in the scientific world, the starting point of
binomial nomenclature.
In addition Linnaeus developed what became known as the
Linnaean taxonomy; the system of scientific classification now
widely used in the biological sciences.
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Notables to Remember
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Antoine-Laurent De Jussieu (1748-1836)
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A French botanist, notable as the first to propose a natural
classification of flowering plants; much of his system remains in
use today.
In his study of flowering plants, Genera plantarum (1789),
Jussieu adopted a methodology based on the use of multiple
characters to define groups.
This was a significant improvement over the original system of
Linnaeus, who classified plants into classes and orders based
on the number of stamens and pistils. Jussieu did keep
Linnaeus' binomial nomenclature, resulting in a work that was
far-reaching in its impact; many of the present-day plant
families are still attributed to Jussieu.
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Notables to Remember
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Michel Adanson (1727 - 1806)
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A French naturalist of Scottish descent.
In 1763 he published his Familles naturelles des
plantesin which he developed the principle of a
system of classification distinct from that of
Linnaeus.
Those beings possessing the greatest number of
similar organs were referred to one great division,
and the relationship was considered more remote in
proportion to the dissimilarity of organs.
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Notables to Remember
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Jean-Baptiste Pierre Antoine de Monet Chevalier de
Lamarck (1744 –1829)
A French soldier, naturalist, academic and an early proponent
of the idea that evolution occurred and proceeded in
accordance with natural laws (nature is all there is and all basic
truths are truths of nature.)
Lamarck's contribution to evolutionary theory consisted of the
first truly cohesive theory of evolution, in which an alchemical
complexifying force drove organisms up a ladder of complexity,
and a second environmental force adapted them to local
environments through "use and disuse" of characteristics,
differentiating them from other organisms.
Notables to Remember
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Augustin Pyramus de Candolle (1778 - 1841) was
a Swiss botanist. The authority abbreviation used in
citing plant names he published is "DC.".
He originated the idea of "Nature's war", writing of
plants being "at war one with another" with the
meaning of different species fighting each other for
space which influenced Charles Darwin.
His Principes élémentaires de botanique, contained
the first exposition of his principles of classification,
following a natural method as opposed to the
artificial Linnaen method.
Artificial versus natural classification
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An artificial classification is an
arrangement that is based on superficial or
arbitrary attributions. It is constructed rather
than based on discoveries. A natural
classification, on the other hand, is a
classification that reflects a natural order
supposed to exist and be discovered by
science.
Notables to Remember
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George Bentham 1800–1884)
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An English botanist considered by some to be the premier
systematic botanist of the nineteenth century.
The author abbreviation Benth. is used to indicate this
individual when citing a botanical name.
George Bentham had neither a formal school nor a college
education, but at an early age acquired the power of giving
sustained and concentrated attention to any subject that
occupied him.
His greatest work was the Genera Plantarum, begun in 1862,
and concluded in 1883 in collaboration with Sir Joseph Dalton
Hooker.
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Notables to Remember
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Asa Gray (1810 - 1888)
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Asa Gray is considered the most important American botanist of
the 19th century.
He was instrumental in unifying the taxonomic knowledge of the
plants of North America. Of Gray's many works on botany, the
most popular was his Manual of the Botany of the Northern
United States, from New England to Wisconsin and South to
Ohio and Pennsylvania Inclusive. This book, known simply as
Gray's Manual, has gone through a number of editions and
remains a standard in the field.
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Notables to Remember
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Heinrich Gustav Adolf Engler (1844 – 1930)
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A German botanist, Engler is notable for his work on
plant taxonomy and phytogeography, like Die
Natürlichen Pflanzenfamilien (The natural plant
families).
He was one of the pioneers in phytogeography,
highlighting the importance of factors like geology on
biodiversity, and defined biogeographical regions in
1879.
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Notables to Remember
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Emil Hans Willi Hennig (1913-1976)
A German biologist who is considered the
founder of phylogenetic systematics, also
known as cladistics. With his works on
evolution and systematics he revolutionized
the view of the natural order of beings.
Some Say Phylogenetics,
Some Say Cladistics
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Cladistics (syn phylogenetics) is the hierarchical
classification of species based on evolutionary
ancestry. Cladistics is distinguished from other
taxonomic systems because it focuses on evolution
rather than similarities between species, and
because it places heavy emphasis on objective,
quantitative analysis.
Cladistics generates diagrams called cladograms
that represent the evolutionary tree of life. DNA and
RNA sequencing data are used in many important
cladistic efforts.
Now What?
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There have been a few other methods of
classification since the days of Linnaeus,
but it would seem that all will soon fall by
the wayside, as DNA classification is
likely to replace all previous methods.
However, the binomial system of applying
names will nonetheless remain
(probably?)