Plants

Plants

• Plants are a fascinating group of eukaryotes that have special features that are uniquely adapted to life in water and on land

• These fascinating creatures are often forgotten or ignored

• Remember, they make up the largest part of our trophic pyramid

Plants

• For this chapter we are going to focus on the plants that are on land

• This will focus our ideas to a large section of plants that we interact with everyday

• Land plants make up a large majority of complex plant species

Plant Adaptations

• Plants are non-mobile organisms that draw resources from the land and the air

• Plants anchor themselves in the ground with a group of absorbent cells called roots

• These cells are designed to take in water and various nutrients while keeping plants in position and upright

Plant Adaptations

• Water can easily be lost in any part of the plant that is exposed to sunlight, is warm or is not kept moist

• Most areas of plants that are exposed to the air are covered by a waxy cuticle

• This is a lipid layer designed to prevent moisture loss

Plant Adaptations

• Most O2 and CO2 is absorbed and released through small openings call stomata

• These cells are located on the bottoms of most leaves and open to the air

• They are normally located on the cool and dark side of the leaf to limit water loss

Plant Growth

• Most plants grow very specifically

• Their roots do not grow from all sections at once

• The roots generally only grow from the tip of the plant at a point called the apical meristem

• This allows the root to grow in directions that lead the roots to resources

Plant Growth

• Some plant cells are also elongated by darkness

• Many times plant cells in the stems of plants will elongate when they are in a shadow

• This allows the plants to grow towards sunlight

Plant Transport

• A plant has to connect its soil systems with its air systems to function correctly

• Most plants have specialized tissue that accomplishes this

• The specialized tissue is called vascular tissue

Plant Transport

• There are two types of vascular tissue

• Xylem are dead cells that form microscopic tubes that send nutrients and water from the roots– “Roots to Shoots”

• Phloem consist of (mostly) living cells that distributes sugars through the plant– “Leaves give these”

Plant Reproduction

• Reproduction on land is challenging for a plant

• It must mate to exchange its information without moving

• Their embryos must be kept protected from drying out

• The plant has to get its next generation away from its valuable resources

Plant Reproduction

• Flowering plants produce pollen grains

• These pollen grains contain a male gamete

• These male gametes are dispersed through the air or by animals

• Pollen must travel to a new part of a plant to fertilize

Plant Reproduction

• Once the pollen reaches the female part of a plant, a zygote is formed

• The developing embryo remains attached to the plant and is fed by the parent

Plant Reproduction

• Eventually the embryo is detached from the plant

• If the embryo starts to germinate too close to the parent plant, it would have to compete for resources

• This means somehow the embryo needs to be carried away from the plant

Flowers

• Flowers are a bit deceiving

• Most people think that flowers are a beautiful and sweet smelling thing that a plant produces for every other organism can enjoy

• Flowers have a purpose that is set aside for the plant

Flowers

• Flowers have a bright and sweet smelling appearance to attract organisms to the flower

• It is a devious ploy to help organisms notice them and be attracted to them

• Imagine trying to find these flowers in a forest

Flowers

• If a flower is more fragrant and colorful it will be easier for another organism to find

• This will increase the chances of reproduction

• This is a basic and rudimentary example of fitness

Parts of a Flower

• Flowers do not exist as one part

• They have many different parts that all function and a have a separate and defined function

Parts of a Flower

• The outer part of the flower is commonly surrounded by a protective barriers called sepals

• These generally surround and protect the flower while it develops

Parts of a Flower

• The outermost layers of the flower consist of several specialized leaves called petals

• These petals are designed to make sure that pollinators are attracted to the flower

• They also make sure that pollinators come in contact with pollen

Parts of a Flower

• If you removed the petals you would see a several long rods

• These long rods contain pollen are the male part of the flower

• The anther is a small sack that contains pollen

• The filament holds up the anther

• The stamen is the term used to describe the anther and filament

Parts of a Flower

• Aside from having male parts, flowers also have female parts that accept pollen

• The stigma is the opening that accepts pollen to the female parts of the plant

• The style is the tube that connects the stigma to the rest of the flower

Parts of a Flower

• The ovary of the plant is located below the stigma and the style

• These ovary will have several small eggs inside of it

• Number of eggs will vary based on the plant and flower

• The total of the female reproductive parts is called a carpel