Plants
Dec 29, 2015
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