Flower Anatomy Lesson Plan NRES B 5 6

Flower Anatomy Lesson Plan NRES B 5 -6

Anticipated Problems 1. What are the parts of a flower and their functions? 2. What are the types of flowers? 3. What is an inflorescence and what are the types of inflorescences?

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

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

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

Flowers: Parts and Functions l The male part of a flower is called the stamen. u u u 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.

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

Flowers: Parts and Functions l Below the stigma is a rod-shaped middle part called the style and a swollen base containing eggs called the ovary. u u 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.

Flowers: Parts and Functions l Flowers often have parts that are neither male nor female. u u 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.

Flowers: Parts and Functions l 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. u u When all the sepals are fused together, they form a calyx. Together, the petals and sepals are called the perianth.

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

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

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

Types of Flowers l 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. u u 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 imperfect flower.

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

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

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

Types of Inflorescence l Flowers are borne on plant stems in one of two ways. u u 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.

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

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

Classifying Inflorescence l 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. u liatris, kalanchoe, African violet

Classifying Inflorescence l 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. u u Indeterminate types of inflorescences are racemes, corymbs, heads, and umbels. Freesia, cineraria, snapdragon, and stock also have indeterminate inflorescence.

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

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

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

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

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

Varieties of Inflorescence l 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. u Yarrow

Varieties of Inflorescence l An umbel is an inflorescence having several branches arising from a common point. u u u 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

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

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

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

REVIEW 1. Name the male and female parts of a flower. 2. What makes a flower perfect? 3. How are monocot and dicot flowers different? 4. What is is an inflorescence having several branches arising from a common point?