Plants

C. Bustamante, M.Covington, M. Santistevan, A. Urias, & R. White

Introduction

1950’s classification two kingdoms: plants

and animals Advancement of

Technologies = ability to discern more subtle, yet profound differences in the living world

New 5-kingdom model evolved

Introduction continued… Based on the 5-

kingdom / 2-superkingdom model plants belong to the

superkingdom Eukarya and the kingdom Plantae

(Some authors differ about the definitions of the largest taxons placing Bacteria and Archaea on an equal footing with Eukarya)

Introduction continued…

Distinction of plants from other organisms life cycles rather than by their capacity for

photosynthesis few plants (beech drops, Epifagus,) are heterotrophs,

lost green pigment in the course of evolution and derive their organic material from other organisms

majority are photosynthetic autotrophs, use solar energy, atmospheric carbon dioxide, water, inorganic materials to synthesize organic compounds

dominant contribution: food, fiber, coal, oil, wood and other forms of stored

energy that sustain the rest of the biota, maintain oxygen in the atmosphere

Plant reproduction has the distinguishing characteristic of alternating generations of diploid (double-chromosome) sporophytes and haploid (single-chromosome) gametophtyes, illustrated here for a fern.

Introduction continued…

Some photosynthetic organisms once classified as plants due to color and sedentary habit no longer considered plants because they lack embryos and other criteria for plant classification Cyanobacteria (blue-green

algae), green algae lichens (fungi with bacteria or

protoctist symbionts

Introduction continued…

Differentiation Though cyanobacteria and plants utilize chlorophylls,

greenish pigments, that capture the energy of sunlight And Cyaobacteria were architects of the earth's

atmosphere through aquatic and photosynthetic characteristics,

it was the plants, which emerged to produce and maintain land-based life on the earth

Introduction continued…

All plants, algae, and cyanobacteria that photosynthesize contain chlorophyll “a”

There is also chlorophyll "b", which occurs only in "green algae" and in the plants

Introduction continued…

To date there are some half-million species of plants identified – new ones found each year.

Oldest fossils-430 million years old in the Phanerozoic eon

Have aquatic ancestors appear to have evolved from only a small group of

green algae

Plant Evolution

Prerequisites for survival sunlight for energy, air for carbon dioxide, crucial inorganic nutrients, and water

Coping with life on the land Sunlight, air, and nutrients readily available Need for water to support metabolism and

reproduction drives evolution

Plant Evolution continued…

12 plant phyla divide into two major groups 3 phyla of non-vascular plants (Bryata or, informally,

bryophytes) and 9 phyla of vascular plants (Tracheata or

tracheophytes)

Bryata are most closely related to plant ancestors among the green algae (Chlorophyta)

Non-Vascular Plants (Bryata)

The three Bryata phyla are Hepatophyta (liverworts) Anthocerophyta (horned worts) Bryophyta (mosses)

Non-Vascular Plants (Bryata) Bryophytes differ from vascular plants lacking

vascular tissue plant body is typically a low-growing organism that

lacks differentiated leaves, stem, and roots Absorb nutrients directly from the environment,

anchoring to soil, tree bark, and rock via rootlike structures called rhizoids

in contrast to the vascular plants, the dominant phase of the lifecycle is the gametophyte phase

Non-Vascular Plants (Bryata) continued… Bryophyte sperm have undulipodia (flagellae)

that enable them to swim to the female gametophyte, but require fresh water to bear them to the egg

They may also exhibit asexual reproduction, by fragmentation

Uses of Bryata moisture-holding capacity of soils, and when dried, used as fuel

Vascular Plants (Tracheata)

Non-seed-bearing (4 phyla) All reproduce by means of spores rather than seeds

Seed-bearing (5 phyla) “Naked” seeds (Gymnosperms; 4 phyla) Seeds enclosed in the fruits of flowers (Angiosperms)

Contain lignified fluid-conducting vessels Two kinds of vascular cells

Xylem carries water and minerals from the roots to the rest of the plant

Phloem transports photsynthate to other tissues

Seedless Vascular Plants Four Phyla

Lycophyta (club mosses) Psilophyta (whisk ferns)

Seedless Vascular Plants continued… Four Phyla

Sphenophyta (horsetails) Filicinophyta (ferns).

Seedless Vascular Plants continued…

The earliest seedless vascular plants lacked differentiation of tissues between root and shoot, and between stem and leaf.

The evolution of these tissues enabled plants to reach great sizes.

In all vascular plants, the sporophyte is the dominant life-cycle phase.

Seedless Vascular Plants continued…

Some uses include lubricants fireworks medicines

Some are edible for humans, but poisonous to livestock.

Ferns provide food, thatch, tea, dyes, medicines, and even pillow stuffing.

Gymnosperms (Naked seeds)

A seed is a mature ovule enclosing an embryo and stored food within a durable coat. It provides enormous advantages in survival over freely

dispersed spores. Gymnosperms, like seedless plants, are

heterosporous. i.e., sharp differences between male microspores

(pollen grains) and female megaspores They include 5 orders, 15 families, about 70

genera, and 730 species.

Gymnosperms (Naked seeds) continued…

Four gymnosperm phyla are Cycadophyta (cycads), Ginkophyta (represented by the a single surviving

species Ginkgo biloba), Coniferophyta (conifers), and Gnetophyta (gnetophytes),

Gymnosperms (Naked seeds) continued… Seed production evolved

by at least 360 million years ago. extinct progymnosperms

produced seeds, but no flowers or fruits

Cycad cones exhibit an early (possibly the earliest) animal pollination system, attracting insects with odors and heat

Gymnosperms (Naked seeds) continued… Cycads - palm-like, but

not true palms live in the tropics and

subtropics; are listed as endangered species

uncooked seeds are toxic to humans and livestock,

cooked seeds are edible leaves are used as thatch

and dressing for wounds

Gymnosperms (Naked seeds) continued… Ginkgo- leaf veins

that split into two smaller veins edible; leaf extracts have

found medicinal uses

Gymnosperms (Naked seeds) continued…

Confers — largest gymnosperms Uses include

lumber and other wood products pulp, resin products, edible seeds, and medicinal

Gymnosperms (Naked seeds) continued… Gnetophytes – live in a wide variety of regions

Namibian Desert, North America, Mediterrenean, and Himalayas to Mongolia

Uses include: Medicinal, and Limited as food

Angiosperms (flowering fruit bearing) Anthophyta – the most

abundant plants produce flowers, wherein

fertilized eggs become seeds surrounded by nutrient-bearing fruits

include plants as grasses (e.g. corn, wheat, barley), lilies, daffodils and palms

Flowers may be single or clustered

reproductive elements of the flower are the stamen and the pistil

Angiosperms (flowering fruit bearing) continued…

Provide the basis for most human foods and the source of most pharmaceuticals.

Plant Relationships

Plants occur in many ecosystems and adapt to climate and precipitation, elevation, and soil types.

Plant communities that are found over large areas are referred to as biomes.

Plant Relationships continued…

Plants provide (living) structure to the ecosystem as cover soil (grass), middle canopy (shrubs), upper canopy (trees)

And additional surface area as roots, leaves, stems, branches,

and trunks Which it provide a means of

exchange for materials and energy as well as habitat for other organisms

Plant Relationships continued…

Biodiversity - amount of different kinds of living organisms in an ecosystem

Can also be described by the differences between individuals of the same

species (intraspecific diversity). Studies show that stability of an ecosystem is

positively related to the diversity present.

Plant Relationships continued…

Plants are producers in ecosystems. Autotrophs – produce their own food. Derive energy from the sun Convert atmospheric carbon into sugar

(photosynthesis). Consumers get their energy from consuming

producers. Carbon is the basis of life on Earth and is largely made

available to the other kingdoms by the plants. Plants provide carbon in the form of dead plant matter

(shed leaves, needles, stems, twigs, rotting trunks, etc.) to the soil environment

Plant Relationships continued…

Plant respiration produces oxygen! Oxygen is central to the metabolism of the other

kingdoms, especially the animal and fungi kingdoms.

Integral with the production of biomass, plants require sugar to provide energy for growth, defense, and reproduction.

Plant Relationships continued…

Herbivory primary producers and

provide the basis for secondary productivity (herbivory or grazing) Energy relationship between

primary and secondary producers may differ by an order of magnitude (i.e., as little as 10% of the biomass consumed becomes biomass for the consumer).

Plants are central to the survival of consumers by the transfer of biomass

Plant Relationships continued… Herbivory continued…

plants also provide nitrogen. although the atmosphere is

largely composed of nitrogen (79%), the gaseous phase of nitrogen (N2) is not available to living systems

nitrogen pathways are complex and mediated by a plethora of bacteria species.

Nitrogen, fixed by bacteria and assimilated by plants is available to other kingdoms by grazing (animals) or decomposition (bacteria and fungi).

Nitrogen Cycle

Nitrogen Cycle

Water Cycle

Plant Relationships continued…

Plant Communication Respond to light, gravity, nutrients, and touch Signal via sight, smell, touch, and chemical signals

Plant Relationships continued…

Disturbance and Succession – unable to move Disturbances can be any event that drastically alters

the structure and function of an ecosystem such as fires, floods, landslides, or any other natural (or unnatural) disaster.

Plants will begin to reestablish themselves in the cleared area by a process of succession.

Plant Relationships continued… Co-evolution wind, earth, fire, and water are central to the

survival of plants and other kingdoms Many plant species would not be able to

continue without the relationships with other organisms

bacteria and worms are central to maintenance of fertile soils and process organic matter

Animals are important to seed germination and dispersal

Mycorrhizal fungi connect roots of the plant Human agriculture

Conclusion

Plants are primary producers in terrestrial ecosystems

Convert abundant sunlight, carbon dioxide from the atmosphere, plus water and minerals from the soil, into energy-bearing food for organisms in all the other kingdoms.

Plant Evolution continued…

Vascular plants divide further non-seed-bearing (4

phyla) and seed-bearing (5 phyla),

with seed bearing

fossil record includes extinct plant phyla Zosterophyllum and Rhynia with the oldest vascular plants, the lycopods (club mosses)