Prepared December, 2010


       

In Celebration of Psalm Nineteen:
God's handiwork in Creation

Chapter 10
The Creation of Plants

UNDER CONSTRUCTION

NOTE:  Chapters 9-11 will be reorganized in the final version.

The first life to appear on Earth is bacteria, followed (in the fossil record) by animals and then plants. There is nothing "alive" that is more basic than bacteria -- alive in the sense that it can exist non-parasitically, apart from the provision of essential services by another living species.

Virtually all of the animal body plans (phyla) show up in the fossil record at essentially the same time, in the Cambrian Era, about 540 to 500 Ma. Plants don't show up for another 100 My, and when they do, the various phyla appear over a protracted period of time, between about 450 and 100 Ma (see below).


This is a curious fact, particularly since one would think that plants are lower forms of life, compared with animals. One explanation is that plants live on land or near the surface of water, and thus are exposed to the harmful effects of high energy cosmic rays. The ozone layer which provides effective protection did not grow into an effective barrier against these rays until about 350-400 Ma, and so this may have delayed the arrival of plants.

Cosmic ray damage is mostly a problem to higher, more organized, forms of life including plants and animals, because so many things have to be intact to carry on life. Bacteria may be able to thrive even in the presence of lethal cosmic rays, because of their very high rate of reproduction, as well as their small size. Damage would occur, of course, but the death of myriads of bacteria, simply provides that much more food for the rest. As long as the lethality rate does not exceed the reproduction rate, the bacteria will thrive.  Thus it is highly probable that almost as soon as enduring dry land and marshy shallows appeared, bacteria migrated from the marine to populate the land habitats.


A consequence of this is that by the time the early plants and animals arrived, there were abundant bacteria available to provide food. The first animals fed on microscopic bacteria or on other animals because plant food was not available. Once plants appeared, the animals used plants for food, but by this time the basic animal body plans, including the digestive systems and other organs had long been established. Clearly these body plans did not come into being because of the availability of plant food; rather the animals adapted to accommodate plant food.





"The earliest photosynthetic organisms on land would have resembled modern algae, cyanobacteria, and lichens, followed by bryophytes (liverworts & mosses, which evolved from the charophyte group of green algae). Bryophytes are described as seedless, nonvascular plants. Their lack of vascular tissue for transport of water and nutrients limits their size (most are between 2 and 20 cm high). Bryophytes don't have typical stems, leaves, or roots, but are anchored to the ground by rhizoids. They can grow in a wide range of environments and are poikilohydric: when the environment dries so does the plant, remaining dormant while dry but recovering rapidly when wetted. These features make them important pioneer species."

About 425 million years ago a new type of plant appeared: these were the vascular plants, with their homoiohydric lifestyle. The earliest known vascular plants come from the Silurian period.

This is achieved by:
Controlling water loss (waterproofing, cuticle)
Controllable valves in cuticle for photosynthesis (stomata)
Replacing lost water, internal conducting tissue (xylem): vascular plants 3D structure: minimises surface area, provides support Ventilated tissue for enhanced gas exchange (internal intercellular spaces) All modern land plants - with the exception of the bryophytes - have these features. There was also competition for light, leading to pressure to increase productivity, which could be achieved by increasing the area available for photosynthesis (evolving leaves) and/or keeping stomata open for longer. This meant that mechanisms for obtaining and transporting water also needed improvement. Thus, evolution was a slow, continuous, linked improvement in water relations and productivity increase. Diversification of land plants Once these features had evolved, there was a substantial diversification of land plants during the Devonian period (408 - 362 million years ago). These included lycophytes (the clubmosses are the best-known modern members of this group:), horsetails (e.g. Equisetum), and progymnosperms, intermediate between seedless vascular plants and the seed plants. While the early forms were small & lacked woody tissue, the first tree-like plants (including progymnosperms and tree-sized lycophytes) had appeared by the mid-Devonian. The first real trees (e.g. Archaeopteris) had developed by the late Devonian, and the seed-bearing gymnosperms had evolved from the progymnosperms by the end of this geological period. The appearance of trees had a significant effect on the environment, because their advanced root systems influenced soil production and led to increased weathering.

Seeds vs Spores

The earliest evidence for the appearance of land plants, in the form of fossilised spores, comes from the Ordovician period (510 - 439 million years ago), a time when the global climate was mild and extensive shallow seas surrounded the low-lying continental masses. (These spores were probably produced by submerged plants that raised their sporangia above the water - wind dispersal would offer a means of colonising other bodies of water.) However, DNA-derived dates suggest an even earlier colonisation of the land, around 700 million years ago.

While the earliest-known seeds date back 365 million years ago, they must have begun to evolve much earlier. While spores are easy to disperse, they have few reserves to establish themselves. This means that a spore reach a wet area, germinate rapidly, and begin photosynthesising straight away to gain energy for the next phase of the lifecycle. Thus sporeproducing plants are limited to wet environments for at least part of their lifecycle. In comparison, a seed contains a young plant and a nutrient store for that plant. This means that seed plants (gymnosperms and angiosperms) can colonise areas with transient or sub-surface water as the young plant can establish itself extremely rapidly once it has germinated. The evolution of the seed underpins the success of the gymnosperms and angiosperms.


Gymnosperms, especially the cycads, remained the dominant land plants in the Jurassic (208 - 145 million years ago), but the Cretaceous (145 - 65 million years ago) saw the rise of the flowering plants (angiosperms) and their associated insect pollinators (an example of coevolution). There are around 235,000 species of angiosperms but they all share a particular set of features: flowers, fruit, and a distinctive life cycle. Because of this, angiosperms are assumed to be a monophyletic group. The angiosperms owe their success to the evolution of the flower. The flower's pollen and nectar encourage pollinating animals to visit, increasing the odds of fertilisation by ensuring that pollen is transferred efficiently from flower to flower. (The flowers of wind-pollinated angiosperms, e.g. grasses, are very much reduced in terms of size and complexity.) After fertilisation the carpel and other parts of the flower are used to form fruit that aid dispersal of the seeds inside the fruit. In addition, the xylem vessels of angiosperms allow very rapid movement of water through the plant. This means that flowering plants can keep their stomata open through much of the day, achieving higher photosynthetic rates than gymnosperms; this "spare" photosynthetic capacity can support the development of fruit. Two major groups of angiosperms are the dicotyledons (more correctly, "eudicotyledons") and the monocotyledons, which include the grasses. Grasses evolved in the Eocene (56.5 - 35.4 million years ago), and this led in turn to the evolution of browsing mammals during the Oligocene (35.4 - 23.2 million years ago).


Timeline of plant evolution


CHECK:
"alternation of generations"
haploid/diploid - Tudge p. 24. diploid = ? double chromosomes?
haploid/diploid  stages of life. In sexual animals: diploid is normal. egg and sperm are haploid, and join at fertilization to form a diploid.

mosses: normally haploid. Then two separate cells "mate" and form temporary diploid which forms next generation *& again haploid (???)
most other plants: diploid is normal stage just as most animals.
 

fractal

http://en.wikipedia.org/wiki/Geologic_timescale


fractal
MOVE UP

PLANTS:
• Roots
Xylem  The valves, etc. and operation.
• Phloem
Conduct food from leaves to the rest of the plant. Companion cells and sieve cells. Companion cells load sugars into the sieve elements (controlling concentration for osmosis?).
Diagram of Phloem Cells
    Sieve plate.




• Leaves -- Cutin, Stamens, respiration, etc.
• Different mechanisms across types
• Cell Division
• Mitosis, etc; sexual reproduction
• Symbiosis with animals

ON THE MOVEMENT TO LAND.  Moving to land began seriously about 470 My ago, some 100 My after the Cambrian explosion. By this time corals, mollusks, and other sea creatures were long established. Some early fungi appeared at about 500 My and mosses about 470 My, both in the Ordovician era. These all lack real roots, so they can only be small and can only grow in water or wet surroundings. However, they could move from shorelines to the interior of land masses, provided the necessary bacteria had preceeded them to supply food and nitrogen, because they have the ability to go into a dormant state during dry periods.

    Cosmic and solar radiation at this time was still severe, but for these simple plants, that was only an inconvenience, because every plant zapped by radiation became food for other plants. As long as their reproduction could keep ahead of the destruction, they were able to cope.

    The really serious issue was water, more precisely, the retention of water in the plants that were exposed to dry land and air. By the start of the Silurian age, 430 My ago, the algae and mosses appear with waxy coats that prevent drying out, and from this point they spread all over the dry land. The waxy coating is characteristic of all land plants from this time on.

    Club mosses show up around 420 My ago. They are the first fossils that have roots and a vascular system to transport dissolved minerals and water between the roots and the rest of the plant. At the same time, spores, which protect plant embryos in damp environments, appear. Club mosses are common and can be easily found in woodland environments at the base of trees and in other damp places.

    It is difficult to over-state the marvelous creative innovations that these roots, vascula and spores represent. The vascular system, for example, includes two separate systems called the xylem and phloem, for transport of food to and from the main body of the plant. Flow depends on capillary action and control of the concentration of dissolved material in the cells, so that osmotic pressure will cause water and solutes to move against gravity (osmotic pressure causes water movement toward cells that have a higher concentrations of dissolved material). Osmotic pressure also maintains the shape and rigidity of plants. Another innovation is the specialization of different parts of the plant for mineral absorption (roots) and food production.

    Ferns appeared next, about 400 My ago. Ferns have large leafs with a web of veins, an improvement over club mosses. Early fern trees and conifers appear about 50 My later, early in the Carboniferous era, about 370 My ago.  The Carboniferous age is the time that the great coal deposits were formed.

    Up to the mid-Carboniferous era, all the land plants live in swamps or very wet environments, because they do not have true roots and woody stems. This early part is called the Mississippian era. The latter half of the Carboniferous era, when true roots are created, is called the Pennsylvanian era. The carboniferous age is the time when many of the great coal deposits were made. Note that these deposits removed a lot of carbon from the environment. Note also that there were no large land animals to feed on the plant life, so that full ecological recycling did not take place.

    The carboniferous age ended with a long ice age. I don’t suppose that anyone knows why there was an ice age at this time, but it could well have been the result of a long-term cooling sun cycle, or, perhaps the environment was so depleted of carbon dioxide by burying of carbon in the coal deposits that the greenhouse effect died out.

    The next stage was the creation of two things almost simultaneously: winged insects and true seed plants. These show up in the fossil record at the end of the Pennsylvanian era, or the start of the Permian age, about 300 My ago. True seed plants are distinguished from spore-bearing plants by the fact that the seeds have true embryos, food and a hard coating for protection.

    This was the first time that land plants had the ability to spread throughout dry land, and were no longer tied to swamps or wet areas. This is also the first time that the ozone layer is completely in place and allowed plants to survive on dry land by shielding the land from solar and cosmic radiation. So, in fact, the seed plants, the first true dry land plants, were created as soon as survival on dry land was possible.



The Silent Speech          The Fossil Record of Species Diversification





All plant and animal species developed initially in the oceans. The dry land was relatively sterile, because of the bombardment with cosmic rays. Once oxygen had reached a stable 20-25% content in the atmosphere, these cosmic rays interacted with the oxygen to build up an ozone layer. This process took a very long time, but around 400 Ma lower forms of life began to populate the dry land, beginning in protected (shaded) areas and gradually "greening the land".

Plant timeline (media-2.web.britannica.com)

land plants -> vascular plants -> seed plants
cuticle (cutin) 460Ma ->fungal interactions 450 MA ->phloem/Xylem 430Ma->Stomata 430Ma->lignin (woody?) 420Ma->roots 400Ma
http://en.wikipedia.org/wiki/Timeline_of_plant_evolution
http://en.wikipedia.org/wiki/Timeline_of_evolution


Note that at various points in plant development, there is a symbiosis between plants and animals. Many plant/animal combinations such as bees and polinated flowers had to occur in concert.

Many developments occurred to address specific needs - such as the plant roots and plant stem structures needed to provide the strength to support large plants.

Problems Solved by Plants

• How to propagate and survive in extreme conditions.
    Solutions: Spores, pollen, seeds.

• How to avoid drying out in the atmosphere?
    Solutions:
        Cutin (waxy layer on leaves),
        Stomata (openings in leaves)

• How to get water and nutrients to plant extremities?
    Solutions: roots and vascular system
        Note: solution implies a complex control of             solutes  and a mechanism for water transport.

• How to support weight in air, maintain rigid form
    Solution: root system to anchor in ground;
        cellulose for low plants (osmotic pressure);
        woody tissue for taller plants.







fractal

NOTES
http://en.wikipedia.org/wiki/Timeline_of_plant_evolution

the role of fractals -- leaf design, tree shapes, etc. What this implies for algorithmic body plans.

http://en.wikipedia.org/wiki/Plant_evolutionary_developmental_biology

http://en.wikipedia.org/wiki/Timeline_of_evolution

Plant Kingdom
Figure 01
The Plant Kingdom Phyla
From Margullis, Kingdoms & Domains p.412
   

Fossil Record of Plant Development
See also Plant Innovations
    All plants develop from embryos and are multi-cellular eukaryotes[FOOTNOTE: Margullis, Kingdoms and Domain, p. 413].
?? All plants have cell walls containing cellulose??
Wiki - vascular plants first appear during Silurian Era. Seed plants in Devonian: Pteridosperms (seed ferns) and Cordaites, both now extinct.

See Wiki article, Evolutionary history of plants

Phylum
Innovation
Date (Ma) of earliest fossils

Cyanobacteria (B-6) photosynthesis
nitrogen fixing
heterocysts
atp synthesis (energy storage)
sucrose cycle (Calvin cycle)
proton pump
spores (akinetes)
Spores protect the living cell by surrounding the cell with a thick wall that can resist dessication, heat, and even the vacuum of space for prolonged periods of time.
3,500 Ma


The first fossil living species were already colonial -- witness the cyanobacterial chains and the stromatolyte formations. Cells in a colony differentiated their tasks -- for example, nitrogen fixing heterocysts had to be specialized because fixing is poisoned by the oxygen byproduct of normal cell metabolism. After the invention of the eukaryotic cell, multicellular plants and animals arose. Multicellularity is caused by a delay in the process of cell separation after division.



Eukaryotic Cells
~1,500 Ma



First Multicellular Plants and Animals
~600 Ma?? (Ediacara)


Kingdom Fungi Not considered part of the plant kingdom by Lynn Margulis."fungi are clearly more closely related to animals than to lants, considering that chitin is the main component of both fungal cell walls and the arthropod exoskeleton. Plant cell walls instead contain cellulose."[FOOTNOTE: Ibid., p. 382]
~500 Ma (Ordovician)


Kingdom Protoctista
single-celled eukaryotes
Algae, seaweeds slime-molds. Do not develop from an embryo as in plants; therefore, not considered part of the plant kingdom by Lynn Margulis. Many are mobile with undulipodia (a special kind of flagella or cilia) during part of their life cycle.[FOOTNOTE: Margullis p120]
~540 Ma (Cambrian)


The earliest animals appear in the fossil record before the earliest fungi and plants. A possible reason is that the early animals all developed in water environments, protected from harmful cosmic rays. Plants and fungi are basically land-based, and so could not fully develop until the cosmic rays were at least partly mitigated by the ozone layer.




Migration to Land
~470 Ma.


Migration to land faced a number of problems:
Cosmic Radiation. The atmosphere's ozone layer protects land plants and animals from most high energy cosmic and solar rays. It first became effective around 400 Ma. Some early fungi appeared at as early as 500 Ma and mosses about 470 Ma, both in the Ordovician era. Cosmic and solar radiation at this time was still severe, but for these simple plants, that was only an inconvenience, because every plant zapped by radiation became food for other plants. As long as the plants could find some shelter from direct rays (overhangs, soil, depressions, water) and their reproduction could keep ahead of the destruction, they were able to cope.
Dessication. A more serious problem for migration to dry land was the need for water. This limited the earliest land plants to moist environments.
Structural Support. A water environment provides  considerable support for weighty bodies, but when plants grew into the atmosphere, they had to support their own weight. Thus early land plants were limited to low-rising masses.




Vascular Plants.
~450 Ma


Club Mosses,
Lycopods  (PL-4)
At one time were very prolific -- heights to 40m in the carboniferous age (350-290 Ma). No true root -- grow from rhizomes as do some of the non-vascular plants  (mosses, etc.)
400 Ma. Carboniferous


Horsetails (PL-6)
Prolific in carboniferous age  -- heights to 15m.



Ferns (PL-7)
Prolific in carboniferous age  -- heights to 25m. Require moist environment for fertilization.




dessication resistance This innovation was needed before plants could thrive in a dry atmosphere. Major innovations involved:
     • Pollen Tube. This allows fertilization in a dry environment[FOOTNOTE. ibid., p. 419]. From the Gincko (Pl-9) and later.
     • Leaves (flat areas for chlorophyll) originated in the Devonian Era (around 400 Ma).
     • Cutin -- a waxy layer to retain moisture in all plant surfaces that exist in an air environment (such as leaves and stems); and
     • Stomata -- pores in the leaves that can open or close to control respiration.
"Leaves did not become widespread in fossil floras until 50 million years after the emergence of vascular plants." ref (Devonian around 400 Ma)




Early Seed Plants (Lyginopterids) in Devonian
380 Ma


Land Plants appear in the Middle Silurian - about 420 Ma. The first true seeds about 380 Ma.


see: "Greening of the Land" Chapter XXIII of Rich, The Fossil Book



root system

vascular structures
     • Cellulose
     • Phloem
     • Xylem 
     • Woody tissues

(425Ma) Cooksonia


cell wall/woody structures




gametes/sexual reproduction




gymnosperms



Flowering Plants (Anthophyta -- PL-12)
angiosperms (flowering plants) (Co-evolved with Bees)
 -- the angiosperm seed "The greatest of all evolutionary innovations"[FOOTNOTE: Margulis K&D p457].
NOTE: The Cretaceous era extends from 145.5 ± 4 to 65.5 ± 0.3 million year. It is characterised by chalky formations. The genesis of the Flowering Plants coincides with this era.  Q: Is the creation of the grasses (Graminoids) at the end of the Cretaceous or the beginning of the following era? Note the Chicxulub meteor ended the Cretaceous Era.
140 Ma (pollen grains)


-- family Garamineae or Poaceae
grasses (Graminoids)
    included bamboos (grow from bottom???)
First appear during the Eocene, around 50Ma[FOOTNOTE: Rock of Ages p. 269]. From this time onward, many modern species appear in the fossil record[ibid.].

• Grow from stem up (unlike most other plants which grow from the tips)
50 Ma







Bryophytes non-vascular plants (algae)



Tracheophytes
vascular plants (algae)




Q: WHEN DID THE LAST MAJOR INNOVATION OCCUR?  GRASSES??
Cellulose, Lignen?



Non-Vascular plants (Subkingdom Bryata, Phyla Pl-1 to Pl-3)

Margulis suggests of the first three plant phyla that "Hornworts, mosses and liverworts [phyla Pl-3, Pl-1, and Pl-2 - dcb] probably evolved independently of one another ... and give rise to no other plant lineage."[FOOTNOTE: Ibid., pp. 427, 428]. These phyla include all non-vascular plants -- that is, they do not have an organized way (xylem and phloem) to move liquids throughout the plant. As a result the plants are small in size and require dampness to grow (although they may have remarkable abilities to survive dessication).

Because these plants are small and soft-bodied, early fossil evidence is problematic and depends on special fossilizing conditons.

Pl-1 Bryophytes -- the mosses.  Mosses are non-vascular, so they are necessarily small and must live in wet or damp areas. Reproduction  must occur in the presence of water so that the male sperm can swim to the female sex organ. The fertilized spores generally disperse in wind currents. Some mosses are also capable of asexual reproduction.


The mosses are soft-bodied and small, and so fossils are rare. Figure ?? is the oldest fossil moss, Pallavicinites devonicus, from the Upper Devonian (ca. 370 Ma) of New York.

Earliest Fossil Moss
Figure ??
Fossil Bryophyte
Devonian ca. 370 Ma
Ohio University


Bryophytes in Amber. The Dominican amber is one of very few sources of fossil mosses[FOOTNOTE:Frahm & Newton A New Contribution to the Moss Flora of Dominican Amber, The Bryologist 108(4):526-536. 2005. This article contains numerous illustrations, including the one shown here]. The amber was fossilized in the Eocene era (56-34 Ma) from an extinct species of Hymenaea, a large tree found in forest areas from Mexico to Brazil.

Moss  in Amber
Figure ??
Calyptothecium duplicatum
Fossil Moss in Dominican Amber
Eocene (56-34 Ma)
Frahm & Newton,op. cit.


Pl-2 Hepatophyta -- Liverworts. Non-vascular. The name comes from the liver-shaped head of the male spore-producing stalk. ??WHAT IS DISTINCTION FROM MOSSES?? Compared with mosses, liverworts have flattened leaf-like body  attached in a ribbon-like branching structure and rhizoids which function much like roots for attachment and food uptake. [CHECK!!]

Earth's oldest liverworts—Metzgeriothallus sharonae from the Middle Devonian (See Wiki article).

Pl-3 Anthocerophyta -- Hornworts. Non-vascular. The name comes from the horn shape of the male spore-producing stalk. Some varieties are host to nitrogen-fixing bacteria, so that they can derive nitrogen from the air and live on bare rock. This makes the hornwarts one of the first successful invaders of sterile land.

The hornworts are relative late-comers in the fossil record, first appearing in the Cretaceous Era (144-65 Ma) contemporary with the flowering plants. This seems very late from an evolutionary point of view[FOOTNOTE: UCMP on Pl-3].
The "horn" is unusual because it grows from the base -- an undifferentiated "stem cell" called the meristem -- (like grasses): most plants grow from their tips.

The earliest unambiguous fossil hornwort was preserved in Dominican Amber, dated to about ?? Ma.


Vascular plants (Subkingdom Tracheata, Phyla Pl-4 to Pl-12).

All vascular plants have vascular tissue which transports nutrients and water throughout the plant. Because of this specific provision for circulation, the vascular plants can (in principle) grow much larger than the non-vascular plants -- although other changes have to accompany the provision of vascula -- such as ways to preserve and control moisture content, strengthening of cell walls for support, and ways to promote vascular flow in the face of gravity.

The vascula consist of the Xylem and Phloem. The {DESCRIBE XYLEM AND PHLOEM} What is the difference Xylem vessels and Tracheids?

Xylem or Tracheid -- draws dissolved nutrients and water up from the soil throughout the plant body.

Xylem consists of Tracheids.
Tracheid -- non-living hollow cells in form of tubes to transport water & solutes. Usually constructed with lignin.

Phloem -- living hollow cells (without nuclei or ribosomes) that conduct nutrients from source of production. They are
joined by sieve plates.

Pollen, Spores and Seeds

Plants may have both sexual (requiring fertilization of a male and female cell) and asexual means of reproduction -- as is also the case with most single-celled species of life. Sexual reproduction of plants involves spores or seeds. The primary distinction between spores and seeds, is that spores fertilize outside the parent's body, whereas seeds fertilize and mature within or on the parent's body. [CHECK!!!] Seed plants may disperse a powder-like Pollen of male cells to provide cross-fertilization between plants, with the actual fertilization occurring within plant ovaries. This accomplishes the cross-fertilization that spores also provide.

Spores. Spores appear first in the fossil record during the middle Ordovician Era (~470 Ma). Spores form in groups of four called spore tetrads. There are two types of spore anatomy: monolete and trilete which differ in the way the original mother spore (sporophyte) divided into four[FOOTNOTE: The sporophyte is diploid (double strand chromosomes). The sporophyte divides once and then each part forms two haploid (single strand chromosomes) spores, hence four spore form togeether[FOOTNOTE: See the New World Encyclopedia entry on Spore Formation]. If they divide like orange slices, the result is a monolete spore with a single scar marking the joining point. If they divide like a tetrahedron, the result is a trilete spore with three scars marking the joining point with the other spores.

Spores Early Devonian
Figure ??
Early Devonian Spores
Jauf Formation
NW Saudi Arabia
Pierre Breuer et al. A Classification of Spores (2007)


Devonian Spores
Figure ??
Spores
Middle Devonian
Chigua Formation, Bolivia and Brazil
note trilete marks

[FOOTNOTE: For further images of pollen and spores see ref. Eckart Schrank below.]

Seeds. Seeds made it possible for plants to live away from moist environments during reproduction. [Rich p386]
Carbonaceous Seed
Figure ??
Carboniferous Era Seeds



How long can pollen, spores and seeds survive?


Spores --  note two classes of spores mono and tri. etc.  intexine and exoexine
Pollen --

See http://www.benbest.com/misc/DNAamber.html Claims to get dna from amber appear to be false -- due to contamination. Not reproducible. ... There are sound theoretical reasons for believing that DNA could not survive hydrolysis & oxidation under such conditions for more than 50,000 to 100,000 years [NATURE; 365:700 (1993) and NATURE; 366:513 (1993)]. But deep ice cores taken from Greenland permafrost have revealed DNA sequences from plants and insects verified to be between 450,000 and 800,000 years old [SCIENCE; Willerslev,E; 317:111-113 (2007)]. Ice cores taken from Antarctica have the potential to reveal DNA samples that are much older. The entire human genome was sequenced from 4,000-year-old hair recovered from permafrost in Greenland [NATURE; Rasmussen,M; 463:757-762 (2010) and NATURE; Lambert,DM; 463:739-740 (2010)].Despite the discovery of lucite & epoxy resins, it has not yet been possible to artificially synthesize amber, the hardest natural resin known.

Compare viable dna from animals trapped in resin.



Wiki: Early land plants reproduced in the fashion of ferns: spores germinated into small gametophytes, which produced sperm. These would swim across moist soils to find the female organs (archegonia) on the same or another gametophyte, where they would fuse with an ovule to produce an embryo, which would germinate into a sporophyte ???

Seeds = complete (fertilized) plants, with food & protective shell [describe how].  You can see the miniature plant in, for example, lima bean seeds: split the seed in half lengthwise and you will see two miniature leaves.

GO INTO THE PROTECTIVE, DISPERSAL FEATURES OF SPORES AND SEEDS. LONG LIVED DORMANCY.

Another difference is that self-fertilization is more likely in the process of spore-based reproduction than in the pollination of a flowering plant. The seed-based process, therefore, has more possibilities for genetic adaptation and evolution."
http://www.suite101.com/content/seeds-versus-spores-a33022?template=article_print.cfm


Remarkable exanmple: Seed Ferns vs modern ferns.






The Mechanics of Sap Flow

capillary action

concentration gradients

osmosis

semipermeable membranes





Cellular Dynamics: What Makes Things Move?
Cellular activity doesn't happen just because it "should"; every specific action in a cell is a "natural" response to physical/chemical dynamics. There are only a few basic ways that this occurs. Thus, when a particular task is at hand, that task can be described exhaustively as a sequence of dynamical tasks that are describable in terms of fundamental physical impulses. A series of sequential tasks (for example the production of sugars) requires a whole set of these things, each of which must not only do its own task, but also set things up for the next task in the sequence.

Some of the following are primitive tasks in themselves, others are composite tasks that can in turn be described as a combination of primitive tasks.

Electric potential gradients. This is a prime mover for molecular reconfiguration, conbination, motion, etc. Example: The movements of the Kinesis molecular motor. Reaction pockets within molecules based on local electrical gradients.

• Solute concentration gradients. Note that different solutes may operate independently to an extent. Example: operation of xylem and phloem in plants.

• Acidity gradients. This is excess/deficiency of H+ ions (== ph).

• Osmotic pressure across membranes. Classical examples: The cnidocyst discharge; xylem and phloem movement between cells.

• Capillary Action. xylem and phloem.

• Condensation and evaporation. Leaf transpiration via stomata "breathing."

• Semi-permeable membrane differentiation.

• Mechanical transport with specialized motor molecules. Kinesin, ATPase, Nitrogenase, etc.

Mechanical reconfiguration. Membrane gate-keepers (e.g. in nuclear membrane, cell wall).

• Key-matching. E.g. t-rna, etc.




Q: How is circulation done in non-vascular plants??? diffusion? or what??? Is it all local???

Pl-4 Lycophyta -- Club Mosses and Lycopods = LycopsidsThese are the oldest vascular plants (having specialized tissues for food transport), dating from about 410 Ma (Silurian Era 443.7-416 Ma), which was the earliest era that left visible fossils (macrofossils) of individual land plants. The innovation of vascula -- particularly the xylem and phloem -- was necessary for plants to leave a water environment and rise into the air (??CHECK). In the Carboniferous Era, lycopods grew to large size and dominated the scene. Many examples of large lycopod trees are found in coal formations -- including complete lycopod forests fossilized in situ, including the Lepidodendron, a large lycopod tree with distinctive leaf-stem markings on the trunk. These forests disappeared from the fossil record near the end of the Pennsylvanian Era (ca. 300 Ma).

Club Moss Pennsylvanian Modern Lycopod
Figure ??
Club Moss -- Pennsylvanian Era
Llantwit seam, South Wales
Geological History of Great Britain
Figure ??
Modern Club Moss


Pl-5 Psilophyta -- Whisk ferns.


The Rhynie Chert

The Rhynie Chert, discovered by William Mackie about 1910[FOOTNOTE: See the remarks on this discovery in the discussion of Phylum Pl-5, K&D, p. 432], is a Devonian formation (about 410 Ma) in Scotland that contains plant fossils in remarkably preserved 3-dimensional form including microscopic structural details, not flattened and distorted as is frequently the case with fossils. The plants were preserved almost instantly by silica-rich water from rapidly rising hot springs. The fossils include algae, fungi and primitive plants and are very early examples of land plants. Individual cells can be seen, including stomata but not true leaves.

The vascular land plant Rhynia is a characteristic fossil of this formation. It is extinct but appears to be an ancestor of the whisk ferns (Phylum Pl-5). These ferns have rhyzoids but no roots, true leaves or seeds but do  have vascula and stomata on the stems. The rhyzoids of both the fossils and living species host symbiotic fungi.
Rhynia Stem
Fossil Stem
Rhynia Cross-section
Cross-section of Fossil
Figure ??
Rhynia gwynnevaughanii
Fossil from the Rhynie Chert
Phylum Pl-5 (?)


R. gwynne-vaughanii discovered 1917.

Asteroxylon mackei, a relative of club mosses (Lycopods).

Aglaophyton major, "pre-vascular" plant


Pl-6 Sphenophyta -- horsetails. The modern horsetail fern is a genuine "living fossil" on the same order of the Gincko tree. These small plants are commonly found in woods. Like true ferns, they reproduce by spores. They were abundant during the Carboniferous Era (450 Ma), growing to heights of ?? ft.


Carbonaceous horsetail
Figure ??
Horsetail Fossil
Carboniferous Era
National Geographic
   
Pl-6x Seed Ferns (Extinct) -- the First Seed Plants. Seed-bearing ferns are a phylum of plants -- the Pteridosperms -- that is now extinct. Ferns today are seedless -- Phylum Pl-7 Filicinophyta (Pteridophyta), the seedless ferns. This is the first appearance of seeds, and it is thought by many biologists that all seed plants descended from this phylum. Prior to the appearance of this phylum, all plants propagated sexually with spores. These are the first extinct phylum of vascular plants identified solely by examining the fossil record[FOOTNOTE: See Dr. Gerhard Leubner's website, The Seed Biology Place -- Seed Evolution for further information on seed evolution].

The Carboniferous era has been called the age of ferns -- actually, the age of seed ferns which often grew to the size of large trees.

Seed Fern
Figure ??
Adiantites machanekii
Seed Fern, Carboniferous Era
Teilia Quarry, England
Geological Conservation review, Fig. 5.42
<>


Seed Fern
Figure ??
Seed Fern
Carbonaceous (Pennsylvanian) Era (~300 Ma)
Wikipedia


Pl-7 Filicinophyta -- true ferns. The earliest fossils of true ferns occur in the Carboniferous era, contemporary with the seed ferns (see above). Ferns similar to modern families rose later, in the  Cretaceous era (145 to 65 Ma) during the heyday of dinosaurs, and also the era of the earliest flowering plants (angiosperms).

True Fern Pennsylvanian(?)
Figure ??
True Fern -- Pecopteris
Pennsylvanian Era (320-286 Ma)
Francis Creek Shale
Coal City, Illinoi
Mazon Creek Fossils
paleojk@earthlink.net

Pl-8 Cycadophyta -- Cycads. Cycads are gymnosperms -- "naked" seed plantsl; that is, they lack the food (derived from the ovaries) that surrounds other seeds. This phylum first appeared in the early Permian Era (299-251 Ma). "The Cycad fossil record is generally poor." -- Wikipedia. Cycads resemble ferns, but typically have fern-like leaves that surround a central seed cone. One variety is the Sago Palm (actually not a palm but a Cycad).

Cycad-Fossil Modern Cycad
Figure ??
Fossil Cycad
ca. 60 Ma??
Czeck Cycads
Polish site
Figure ??
Modern Cycad

 
Pl-9 Ginkgophyta -- Ginkgo tree. The modern Ginkgo Balboa tree is the only living species of this phylum which has a fossil record from the Permian Era. Note the leaf varieties in the fossil species, compared with the varieties in the modern Ginkgo Balboa -- all varieties can show up on a single tree (a similar variation occurs in sassafras trees).

Ginkgo Cordilobata
Figure ??
Ginkgo cordilobata
Lower Jurassic (~ 180 Ma)
Ishpushta, Afghanistan
Hans-Joachim Schweitzer Collection Paleobotanical collection, University of Jena

Ginkgo Leaf Variety Ginkgo Modern Leaf Variety
Figure??a
Fossil Ginkgo Leaf Varieties
Upper Cretatious and Jurassic Eras
Edward W. Berry, Smithsonian (1918)
Figure ??b
Modern Ginkgo Leaf Varieties
All varieties may occur on the same tree
Pencil and Leaf Blogspot


Pl-10 Coniferophyta -- Conifers. Conifers are woody gymnosperm plants that first appear in the upper Carbonaceous era but flourish in the Mesozoic Era
(250-67 Ma)
between the Permian Extinction (251 Ma) and the Chicxulub extinction (65 Ma), the K-T boundary which defined the end of the Cretaceous era and the start of the Tertiary Period. The Mesozoic Era begins with the Triassic Era (250-200 Ma) and ends with the Cretaceous Era.

Conifer Fossil
Figure ??
Conifer Fossil
Mid-Triassic (225 Ma)
Kühwiesenkoph Fossil Repository
Michael Wachtler


Pl-11 Gnetophyta -- Gnetophytes. These are also gymnosperms. Many of them are woody climbers.

Pl-12 Anthophyta -- Angiosperms = flowering plants. Flowering plants arose in conjunction with the arrival of bees and insects that are adapted specifically in pollenation. "flowering plants exhibit a number of evolutionary innovations that appeared rapidly, including novel structures like carpels and primitive petals and sepals, the sine qua non of flowering plants," dePamphilis said. Angiosperms also boast plenty of unique biochemistry. "They're a rich source of medicinal compounds. Even the kind of wood they make is special." http://paleoplant.blogspot.com/ The "Abominable Mystery". This phrase was used by Darwin with reference to the origin of flowering plants. The oldest flowering plants appear in the fossil record at the very start of the Creataceous Era, about 145 Ma. By the upper Cretaceous (around 65 Ma), many of the extant angiosperm families and subclasses had already differentiated. This is considered the rapid radiation of the angiosperms which proceeded to become the dominant component of the world's flora. In many if not most instances, specific angiosperm plant species arose in conjunction with specific insects and other creatures which adapted specifically to forage on them. "Angiosperms and insects are a good example of coevolution." -- Wikipedia. So, for example, bees first appear in the fossil record at 100 Ma.

This period is characterized by the appearance of very large animals -- it is still a feature today that the largest land animals feed on plants (perhaps because plants must be eaten in bulk in order to provide sufficient nourishment).


Archaefructus Sinensis Archaefructus Sinensis Reconstructed
Figure ??
Earliest Flowering Plant
ArchaefructusSinensis
Upper Jurassic Jianshangou Bed (145 Ma)
Liaoling Province, China
Sun, Dilcher, Ji, Nixon Virtual Fossil Collection (2002)
Figure ??
Earliest Flowering Plant
Reconstruction


Flowering plants appear to have developed concurrently with insects that could aid in pollination. "prior to the evolution of bees [angiosperms] didn't have any strong mechanism to spread their pollen, only a few flies and beetles that didn't go very far."[FOOTNOTE: ScienceNews October 26, 2006].

"Flowering plants, among other things, account for practically all of the food plants on Earth and much of the food supply for humans and many other animal species." [FOOTNOTE: ibid.]

Bee Fossil Amber Bee Fossil Amber Sketch
Figure ??a
Oldest Fossil Bee in Amber
Melittosphex burmensis
mid-Cretaceous (100 Ma)
Hukawng Valley of Myanmar (Burma)
Oregon State University, Oct. 2006
Figure ??b
Bee in Amber
Diagram


uua.cn


SHARP POINTS: THE ANGIOSPERM SEED (see remark in box above) and the concurrent development of angiosperms and the insects required to pollinate the flowers.


Grasses. only appear after 65Ma. A remarkable characteristic of grasses is that they grow from their base rather than from the tip. Thus damage to the blades by grazing animals do not kill the grasses, because they continue to grow from the base of the blade. Other plants, such as trees, grow from the stem and branch tips.


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NOTES


Plant Innovations
Ordovician (488 - 443 Ma) to Lower Carboniferous (Mississippian) (359 - 316 Ma) Eras.

Marine plants first appear late in the Ordovician Era, but the Devonian era (416 to 359 Ma) saw the
true "greening" of the land. The massive invasion of plants onto the continents had to wait until the ozone layer first grew to a level that could filter out the most harmful cosmic rays. This is a time in which many major innovations in plants occurred.

Plant Innovations
Figure ??
Plant Innovations
Ordovician to Carboniferous



Plant Body Plans







General plant structure (roots, etc.)

Algorithmic growth patterns -- leaves, tree shapes, etc.

Fractal design -- examples of fractal leaves, etc.




FractalLeaves.jpg

leaf structure algorithms -- general shape and venation

general purpose: veins carry nutrients throughout the leaves. The general logic is recognizable: capillary-size vein tips, which combine into progressively larger capacity veins, ending in the stem.

Branching logic. Can identify "primitive" venation, (mostly straight -- as in gincko? Vs .... Clearly the growth follows simple algorithms. For plants such algorithms replace the detailed topography of animal hox genes.



Microtubules




Food Sources
The very first living species had to rely on inorganic food sources.

Time Period
Living Forms
Food source
Problems
Solutions
3,500 Ma to 2,000 Ma
anoxic bacteria
soluble inorganic minerals
Protein Production
preservation of genetic code
Central Dogma



Source of Energy photosynthesis/ATP



Nitrogen deficiency Nitrogenase/Heterocysts
organic remains
nitrogen-fixing bacteria


organic bacterial remains


2,000 Ma to ±800 Ma
eukaryotes
microscopic organic remains


±800 Ma to 500 Ma
multicellular animals
microscopic organic remains

500 Ma to 350 Ma
marine plants
microscopic organic remains
inorganic minerals



marine animals
plants and animals



land plants
inorganic/organic remains
cosmic rays
Ozone layer developed
about 350 Ma
350 Ma to present
land plants
plants and animals
Nitrogen deficiency
organic remains
nitrogen fixing bacteria

land animals
plants and animals





Suspension of Life
One feature of plant life (and to an extent certain bacterial life) is the fact that it can enter a dormant stage when conditions are not suitable to carry on normal life functions. An interesting question is, how long can the dormant stage persist and still allow resuscitation.

• Water.  Water is essential to carry on biological activity in all species (??CHECK) of both plants and animals.  However many living forms can survive periods of water-deprivation, particularly in the form of spores and pollen. In fact, to survive freezing without mechanical damage, dessication is necessary.

• Vacuum.

• Low Temperatures.

Anecdotes about spores surviving for years in space (on moon, e.g.)



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REFERENCES

University of California Museum of Paleontology
    Introduction to the Plantae
       Plant Systematics
       Pl-3 Anthocerophyta -- Hornworts

Books included in the Golden Age of Geology Library.
    James D. Dana Manual of Geology (1896) -- many fossils presented in systematic manner.
            See in particular the illustrated contents.
    Sir Archibald Geikie, Text-Book of Geology (1902) -- fossils presented in Book VI Stratigraphical Geology.
    Gideon Algernon Mantell, Medals of Creation (1844) An early book with many fossil specimens.

Edward W. Berry, Paleobotany: A Sketch of the Origin and Evolution of Floras (Google Books) FROM THE SMITHSONIAN REPORT FOR 1918, PAGES 289-407

http://books.google.com/books/download/Paleobotany.pdf?id=wyEaAAAAYAAJ&output=pdf&sig=ACfU3U0Y93QQ0M589nrYDVbl-jkUuWtZ8w

Lynn Margulis, Kingdoms and Domains,

Eckart Schrank, Pollen and spores from the Tendaguru Beds, Upper Jurassic and Lower Cretaceous of Southeast Tanzania. (2010) Includes many good spore and pollen images.

Evolutionary history of plants


Patricia & Thomas Rich, Mildred & Carroll Fenton, The Fossil Book: A Record of Prehistoric Life, Dover, (1996), Chapter XXIII p. 372ff; XXXII, p. 534ff).
Warren Allmon & Barbara Page, Rock of Ages Sands of Time, U. Chicago (2001). A pictorial timeline of the fossil record.
Colin Tudge, The Variety of Life, Oxford, 2000.
A Review of the Universe - Structures, Evolutions, Observations, and Theories. This is a very useful review of the creation of the universe, prepared by a "retired physicist" and freely available for use and quotation. In particular the sections relating to plants are:  Evolution of micro-organisms and Plants,   and  Characteristics and Structures of Plants.

Taylor, Biology and Evolution of fossil Plants -- Anthocerophyta

HISTORY  OF  PALAEOZOIC FORESTS: FOSSIL  AND  EXTANT LYCOPHYTES,  PALAEOBOTANICAL RESEARCH GROUP
UNIVERSITY of  MÜNSTER
 
Sara Goudarzi (MSNBC) 10/25/2006 Oldest bee fossil creates new buzz: 100 million-year-old fossil found in a mine in Myanmar


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