Mr. Bouyer
Day 1 - 2 | Day 3 | Lab | Vocabulary Test

Describe each part of a flower and its function. Communicate the importance of angiosperms in the world. Recognize flower modifications. Name the arrangements of multiple flowers on a single peduncle. Use PowerPoint to make study slides.

Plant Identification Assignment.

What is the scientific name of the Pecan, Texas' state tree?

Through the long span of geological time, major groups of vascular plants have risen to dominance, only to decline to a minor remnant in the earth's flora. The angiosperms or flowering plants, are the group that is now in the full flush of its evolutionary development. We are living in the "age of the angiosperms". There are more than 250,000 species, grouped into 12,500 genera and about 300 families. Angiosperms dominate in almost every terrestrial habitat, the tundra and northern coniferous forests being among the few exceptions.

Because of their abundance and widespread distribution, angiosperms constitute a major part of the environment of other organisms. As such, they have exerted a profound effect on other organisms, particularly the animals that feed on them. For example, the evolution of herbivorous mammals has correlated with the worldwide spread of grasses, legumes, and other herbs. Most modern birds have evolved as organisms that feed on either the seeds, fruits, or buds of flowering plants, or on the insects that feed on angiosperms.

Despite their large numbers and diversity, the flowering plants are believed to be a unified group with a common origin. Although there are many variations in the species of angiosperms, the success of the group relates directly to the successful traits of the reproductive structures, flowers, of their ancestors. Flowers are organs of sexual reproduction. In addition to the genetic variation provided by sexual reproduction, flowers are also organs of locomotion. All angiosperms have a specific way of dispersing their seeds, allowing a plant species to move great distances in a relatively few generations.

Basic flower parts:

Receptacle, the top of the stem supporting a flower. The receptacle forms the cup, hypanthium, from which all flower parts arise but is not usually a large or obvious part of the flower.

Sepals collectively are called the calyx, CA. They are the outermost floral parts and are commonly leaf-like and green. The sepals enclose the flower bud and may or may not survive for the life of the flower.

Petals collectively are called the corolla, CO. Found just inside the sepals, petals are usually delicate and brightly colored to attract insects. The sepals and petals together are called the perianth.

Actinomorphic sepals and petals can be divided into equal parts through several longitudinal planes. This is called a "regular" flower.
Zygomorphic sepals and petals can be divided into equal parts through only one longitudinal plane. This is called an "irregular" flower.

Stamens (male reproductive structures) collectively are called the androecium, A. They are the male reproductive parts of the flower and are located inward from the perianth.
• Parts of a stamen:
  • Anther - the sac-like part which contains the pollen.
  • Filament - the stalk connecting the anther to the flower.
• Stamens usually attach to the hypanthium, but may be:
  • Attached to the corolla, epipetalous.
  • Attached to the pistil, gynandrous.
• Stamens may attach to each other:
  • By union of their filaments into a single group, monadelphous.
  • By union of their filaments into two groups, diadelphous.
  • By union of their anthers into a ring, syngenesious.

Pistils (female reproductive structures) collectively are called the gynoecium, G. The female reproductive parts of a flower, the pistil, is located in the center of the flower. A gynoecium may be a single pistil or many pistils, but pistils generally are composed of:

• Stigma - the pollen-receptive part at the top of the pistil.
• Style - the stalk-like portion leading from the stigma to the ovary.
• Ovary - the enlarged portion at the pistil base where egg cells are produced. The basic unit of construction of the ovary is the carpel. Each carpel will eventually produce a seed. One can determine the number of carpels in a pistil by making a cross-section of the ovary and counting the number of partitions, or by counting the number of stigmas or styles.
  • Ovary position:
    • Hypogynous--The flower is hypogynous if the ovary is situated above the calyx and there is no floral cup around it. The ovary is superior.
    • Perigynous--The flower is perigynous if the ovary is situated within (and free from) a floral cup or hypanthium. The ovary is superior.
    • Epigynous--The flower is epigynous if the ovary is situated below the calyx. The ovary is inferior.

In-class Assignment 102:
This assignment must be turned in by the end of class tomorrow to receive credit.

Review the construction of an essay.

1. Use this essay planning guide to write an essay about Angiosperm ancestors.

Day 3

What is a peduncle?

Some flowers do not have all of the basic parts.

Flower types, based on the presence of parts:
• Complete flowers have sepals, petals, stamens, and pistils. The flower pictured at the right is a complete flower.
• Incomplete flowers are missing one of more of the four basic parts.
• Perfect flowers have both stamens and pistils. The flower pictured at the right is a perfect flower.
• Imperfect flowers have either stamens or pistils, but not both.
  • Staminate flowers have only stamens.
  • Pistillate flowers have only pistils.
  • Monoecious plants have imperfect flowers with both sexes growing on the same plant.
  • Dioecious plants have imperfect flowers with only one sex growing on each plant.
• Regular flowers have petals and sepals that are similar in size and shape.
• Irregular flowers have petals and sepals that are dissimilar, the flower is not symmetrical.

Inflorescence types: the arrangement of flowers on a plant.
The main supporting stalk of the whole inflorescence is called a peduncle.
The stalks supporting single flowers are called pedicels.

• Dichasium - A peduncle bearing a terminal flower and a pair of branches producing lateral flowers.
• Monochasium- A peduncle bearing a terminal flower and , below it, one branch producing a single lateral flower.
• Panicle - An elongated inflorencence with branched branches along the central axis.
• Raceme - An elongated inflorencence with simple pedicels along the central axis.
• Spike - An elongated inflorencence with flowers along the central axis that are sessil (do not have pedicels).
• Corymb - A flat-topped inflorenscence with the pedicels of different length.
• Head - A rounded or flat-topped cluster of sessil flowers.
• Umbel - An inflorescence having several branches arising from a common point at the end of the peduncle. If the branches end in flowers, it is a simple umbel. If the branches branch again before reaching the flowers, it is a compound unbel.
• Catkin - A spike or raceme composed of unisexual flowers without petals. The flowers are usually very small and fall as a group.
• Spadix - A spike with a thickened, fleshy axis, usuall enveloped by a conspicuously colored bract called a spathe.

Computer Homework Assignment 103:
This assignment must be completed by the beginning of class tomorrow to receive credit.
PowerPoint Evaluation Rubric
1. Use PowerPoint to make a presentation about flower structure. Each slide should have labeled diagrams or pictures demonstrating each of these flower types:
   1. Slide 1: complete and incomplete
   2. Slide 2: perfect and imperfect
   3. Slide 3: regular and irregular
   4. Slide 4: a flower forming an umbel
   5. Slide 5: a flower forming a compound umbel
2. After these slides are made, use the PowerPoint rubric to add to your presentation, making it as professional appearing as you can. Your facilitator will evaluate your presentation using the rubric.

   Save this file on your computer.
   Show the PowerPoint presentation to your science facilitator.

Research Links:

• Lecture Notes - Botany 201, Texas A&M
• Flower Lab - Botany 201, Texas A&M