Flower Anatomy

1. Flower Anatomy Lesson Plan NRES B5-6

2. Anticipated Problems • What are the parts of a flower and their functions? • What are the types of flowers? • What is an inflorescence and what are the types of inflorescences?

3. Terms • anther • bract • calyx • catkin • complete flower • corolla • corymb • cyme • determinate • dioecious • filament • head • imperfect flower • incomplete flower • indeterminate • inflorescence

4. Terms • monoecious • ovary • panicle • pedicel • peduncle • perfect flower • perianth • petals • pistil • pistillate • pollen • raceme • receptacle • sepals • spadix • spike • stamen • staminate • stigma • style • tepals • umbel

5. Flowers: Parts and Functions • Flowers are the most obvious part of most plants. • Purpose of flowers: for plants to be able to reproduce sexually • Made of many intricate and important parts • Most contain both male and female parts

6. Flowers: Parts and Functions • The male part of a flower is called the stamen. • The stamen is made of the stalk-like filament which holds up the sac-like anther. • The anther contains pollen, the grain released by flowers, which contains the sperm. • Flowers that have only male parts are called staminate.

7. Flowers: Parts and Functions • The female part of a flower is called the pistil. • The pistil is made up of a sticky tissue at its end called the stigma that is receptive to pollen.

8. Flowers: Parts and Functions • Below the stigma is a rod-shaped middle part called the style and a swollen base containing eggs called the ovary. • Once the pollen reaches the stigma, it forms a pollen tube down through the style to the ovary where sperm is deposited. • Flowers that have only female parts are called pistillate.

9. Flowers: Parts and Functions • Flowers often have parts that are neither male nor female. • These are the petals, usually colorful leaf-like structures that often attract animals and insects. • When all the petals are fused together, they form a corolla.

10. Flowers: Parts and Functions • Beneath the petals are more leaf-like structures that are often green, called sepals. The sepals support the petals and protect the flower before it opens. • When all the sepals are fused together, they form a calyx. • Together, the petals and sepals are called the perianth.

11. Flowers: Parts and Functions • With some plants, a clear distinction between petals and sepals cannot be made. • In these cases, the parts of the perianth are called tepals. • Tulip flowers and many monocots have tepals.

12. Flowers: Parts and Functions • Some plants have modified leaves at the base of a flower or floral inflorescence called a bract. • The bracts may be green but in some cases, such as the poinsettia, are colorful.

13. Flowers: Parts and Functions • The flower stem is referred to as the pedicel. • The portion of the pedicel that holds the flower parts is the receptacle.

16. Types of Flowers • Flowers come in many shapes, sizes, and colors. Not all of them have all the structures previously mentioned. Plants may produce flowers that are perfect or imperfect. • A flower that has both male and female parts is called a perfect flower. • A flower that is missing either male or female parts is called an imperfectflower.

17. Types of Flowers • Plants may have flowers that are complete or incomplete. • If a flower has sepals, petals, pistils, and stamens, it is referred to as a completeflower. • If a flower is missing one of these parts, it is referred to as an incompleteflower. • Imperfect flowers are always incomplete. • Incomplete flowers may or may not be imperfect.

18. Classifying Flowers • Plants may be classified as monoecious or dioecious. • Monoecious plants bear both male and female flowers on one plant. (corn, cucumbers, oaks) • Dioecious plants have male and female flowers on separate plants. (soybeans, asparagus, kiwi)

19. Classifying Flowers • A good way to tell the difference between a monocot and a dicot is to look closely at the flowers. • Monocots have flowers with flower parts in multiples of three. • Dicots have flowers with flower parts in multiples of four or five.

20. Types of Inflorescence • Flowers are borne on plant stems in one of two ways. • Some plants have solitary flowers, such as the tulip, narcissus, and rose. • Other plants have flower clusters, known as an inflorescence. An inflorescence is actually the branching system of the stem.

21. Types of Inflorescence • The main stem of an inflorescence is known as the peduncle. • Pedicels that branch from the peduncle support individual flowers.

22. Classifying Inflorescence • One way in which types of inflorescence are classified is by the sequence of flowering within the flower cluster.

23. Classifying Inflorescence • If the first flower to open is at the apex of the stem and the progression of flowering is downward or outward, the inflorescence is determinate. • liatris, kalanchoe, African violet

24. Classifying Inflorescence • If the last flower to open is terminal on the main axis and the progression of flowering is inward or upward, the inflorescence is indeterminate. • Indeterminate types of inflorescences are racemes, corymbs, heads, and umbels. • Freesia, cineraria, snapdragon, and stock also have indeterminate inflorescence.

25. Varieties of Inflorescence • There a variety of inflorescence types. Some common types are cyme, spike, raceme, panicle, corymb, umbel, spadix, catkin, and head. • The spike and the panicle types of inflorescence are the most common among monocot plants.

26. Varieties of Inflorescence • A cyme takes on several forms, although it is usually a flat-topped inflorescence. • Tomato, potato, and alstroemeria

27. Varieties of Inflorescence • A spike is an elongated inflorescence with a central axis along which sessile flowers are attached. • Wheat, barley, ryegrass, wheatgrass, gladioli

28. Varieties of Inflorescence • A raceme is an elongated inflorescence with a central axis along which are attached simple pedicels of more or less equal length. • Foxtail millet, snapdragon, delphinium, Scotch broom, and stock

29. Varieties of Inflorescence • A panicle is an elongated inflorescence with a central axis along which are branches that are themselves branched. • Rice, oats, sudangrass, Kentucky bluegrass, tall fescue, timothy, grain sorghum

30. Varieties of Inflorescence • A corymb is a short and broad, flat-topped indeterminate inflorescence having a main vertical axis and pedicels or branches of unequal length. The outer flowers open first. • Yarrow

31. Varieties of Inflorescence • An umbel is an inflorescence having several branches arising from a common point. • A simple umbel consists of flowers with single pedicels. • Compound umbels have secondary branching in the form of pedicels at the end of a ray. • Queen Anne’s lace and amaryllis

32. Varieties of Inflorescence • A spadix is a spike with a thickened, fleshy axis, usually enveloped by a showy bract called a spathe. • calla lily and anthurium

33. Varieties of Inflorescence • A catkin is a spike, raceme, or cyme composed of unisexual flowers without petals and falling as a unit. • willows, alders, oaks, birch fffffff

34. Varieties of Inflorescence • A head is a rounded or flat-topped cluster of sessile flowers. Head inflorescences of the aster family resemble single flowers. • These consist of centrally grouped flowers called disc flowers encircled by ray flowers. • Gerbera daisy, chrysanthemum, sunflower fffffff

35. REVIEW • Name the male and female parts of a flower. • What makes a flower perfect? • How are monocot and dicot flowers different? • What is is an inflorescence having several branches arising from a common point?