BOT 111.1 Lab exercise 8 PDF

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EXERCISE 8The FlowerName: Gwyneth N. Maratas Date performed: February 18, 2019 Section: BOT 111 BC Date submitted: February 28, 2019I. IntroductionFigure 1. Catharanthus roseus Flowering plants make seeds that are inside a covering. Angiosperm, the name for flowering plants, means “enclosed seed” (C...

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EXERCISE 8 The Flower Name: 2019 Section:

I.

Gwyneth N. Maratas BOT 111.1 BC

Date performed: February 18, Date submitted: February 28, 2019

Introduction

Figure 1. Catharanthus roseus Flowering plants make seeds that are inside a covering. Angiosperm, the name for flowering plants, means “enclosed seed” (Crosby, 2008). Members of the division are the source of most of the food on which humans and other mammals rely and of many raw materials and natural products. Included in the division are most shrubs and herbs, most familiar trees except pines and other conifers, and specialized plants such as succulents, parasites, and aquatic types. Flowering plants occupy almost every ecological situation and dominate most natural landscapes. The characteristic feature of angiosperms is the flower, the function of which is the reproduction of the plant through the development of seeds. Flowers are highly modified shoots made up of four fundamental parts arranged in separate series, or whorls, on specialized stem tips. The outer series consists of the sepals, which are modified leaves or bracts that are usually green. The next inner series, the petals, are also modified leaves, but they are usually finer textured and more conspicuously colored. The third series consists of the stamens, the pollenproducing male portion of the flower. The innermost series is the carpels, female structures that produce the seeds. Carpels are often fused into a structure called the pistil. Moreover, the flower is the main basis in plant identification and classification in traditional taxonomic methods. And in fact, even up to time, the flower is still very important to taxonomy and nomenclature. II.

Objectives The main purpose of the exercise is to observe the structure of a flower, and to identify the function of its parts.

III.

Materials and Methods The materials and equipment utilized in the exercise are the following:

Table 1. List of specimens used in conducting the exercise Hydrangea macrophylla (Big leaf hydrangea) Gladiolus sp. (Sword lily) Clivia miniata (Bush lily) Acalypha wilkesiana (Firedragon) Foeniculum vulgare (Fennel) Daucus carota var. carota (Carrot) Tagetes erecta (Marigold) Cosmos caudatus (Cosmos) Gerbera jamesonii (Daisy) Hibiscus rosa-sinensis (Gumamela) Phaseolus vulgaris (Sitaw) Zantedeschia aethiopica (Arum lily) Pisum sativum (Pea) Ipomoea batatas (kamote) Anthurium sp. Allamanda cathartica (Golden trumpet) Euphorbia pulcherrima (Poinsettia) Ixora coccinea (Santan) Rosa sp. (Rose) Caesalpinia pulcherrima (Peacock flower) Any grass flower Oryza sativa (Rice) Any rose flower Ageratum conyzoides (Goat weed) Table 2. List of materials and equipment used in conducting the exercise Materials and Equipment Function Used to cut and dissect the specimen to be Scalpel examined Used to observed the specimen in Light compound microscope microscopic level Used to mount the specimen under the Glass slides and coverslips microscope Part A. Flower Structure A relatively large open flower that has large, easy to see parts was obtained. The flower was examined and the petals and the sepals were located. Their numbers, size, color, and arrangement on the flower were observed and recorded. The petals and sepals were removed by carefully pulling them off of the flower stem. The stamens were located and the number of stamens were record. The pistil was located. With the scalpel, an anther from the tip of one of the stamens was cut and was examined it with the use of light compound microscope. The anther was placed on a microscope slide. Several drops of water were added to the slide. The slide with the anther under the microscope was examined. With the scalpel, the ovary at the base of the style was sliced in half lengthwise, from top to bottom. One half, cut-side facing up, was placed on a microscope slide. A drop of water was added and a cover slip was placed on the cut face. The many small round structures that fill the ovary half are ovules. Each ovule contains an egg cell and is attached to the ovary wall by a tiny stalk. The egg cells will be too small for you to see with the hand lens but you may be able to count the ovules. An illustration of the observed flower was made and labelled.

Part B. Morphology The type of flower, fusion of floral parts, variation in calyx, variation in corolla, leaf bases, shape of leaves, variations in leaf margins, degree of lobbing in leaves, leaf apex, leaf texture, leaf surface, and other taxonomic terms related to leaves were examined in each specimen. The flowers were classified whether they are regular or irregular, complete or incomplete. The different variation in floral parts were observed and noted in Table 5. The variation in the inflorescences, the cluster of flowers were examined. After examining the inflorescence of several specimens, observations were tabulated in Table 6. 5 flowers specimen were selected to determine the floral formula. Illustrations of the floral diagrams were made each. The different specimens were drawn. These were labelled with the following format. Common name: Scientific name: Inflorescence: IV. Results and Discussion Part A. Flower Structure Flowers typically are composed of four parts, or whorls, arranged in concentric rings attached to the tip of the stem. From innermost to outermost, these whorls are the pistil, stamens, petals, and sepals.

Figure 2. Parts of a flower According to Mauseth (2008), sepals, protective coverings that are closed over the bud before it blooms, are the outermost flower parts. One step inward lies the petals, which serve to attract pollinators using both coloration and scent-producing glands. Inside the petals are the

flower's sexual organs, the stamens and pistil. Each stamen, the pollen producing part of the flower, includes an anther and a filament. At the center of the flower is the pistil, composed of a stigma, a style, and an ovary. Within the ovary is a small cavity that contains the ovule, an eggshaped structure that, when fertilized, eventually becomes a seed.

Figure 4. Actual Hibiscus rosa-sinensis obtained during exercise

Figure 3. Parts of a Hibiscus rosa-sinesis

Hibiscus rosa-sinensis was selected to be examined due to its large, easy to see parts. The identified parts were petals, pistil, anther, style, ovary, and sepals. The specimen has a total number of five (5) petals and six (6) sepals. There were approximately 82 stamens counted in the specimen. There was only one (1) pistil located at the center of the flower which was made up of the anthers, style, and ovary. The observations in the specimen were tabulated in a table. Table 3. Observations of flower petals in Hibiscus rosa-sinesis Petals Number of petals

5

Size of petal (cm)

11

Color of petal

Pink, White and Red

Arrangement of petals

Pentamerous

Table 4. Observations of sepals in Hibiscus rosa-sinesis Sepals Number of sepals

6

Size of sepal (cm)

2

Color of sepal

Green

Arrangement of petals

Gamopetalous

Figure 5. Hibiscus rosasinensis anther in 40x magnification

Figure 6. Hibiscus rosasinensis anther in 100x magnification

Figure 7. Hibiscus rosasinensis pollen grain in 400x magnification

Figure 8. Hibiscus rosasinensis ovary 40X magnification

Figure 9. Hibiscus rosasinensis ovule 40X magnification

Figure 10. Hibiscus rosasinensis ovule 100X magnification

Pollination is the transfer of pollen grains from the male structure of a plant to the female structure of a plant. The pollen grains contain cells that will develop into male sex cells, or sperm. The female structure of a plant contains the female sex cells, or eggs. Pollination prepares the plant for fertilization, the union of the male and female sex cells. Pollen grains are microscopic in size, ranging in diameter from less than 0.01mm to a little over 0.5 mm (Dickson, 2008).

Figure 11. Flower pollination and fertilization Flowers contain the structures necessary for sexual reproduction. The male component, or stamen, consists of a thin stalk called the filament, capped by the anther. The female component, the pistil, includes the stigma, a sticky surface that catches pollen; the ovary, which contains the ovule and embryo sac with its egg; and the style, a tube that connects the stigma and ovary (A). Pollen is produced in the anther (B), and is released when mature (C). Each mature pollen grain contains two sperm cells. In self-pollinating plants, the pollen lands on the stigma of the same flower, but in cross-pollinating plants—the majority of plants—the pollen is carried by wind, water, insects, or small animals to another flower. If the pollen attaches to the stigma of a flower from the same species, the pollen produces a pollen tube, which grows down the neck of the style, transporting the sperm to the ovule (D). Within the embryo sac of the ovule, one sperm cell fertilizes the egg, which develops into a seed. The second sperm cell unites with two cells in the embryo sac called polar nuclei, and this results in the development of the endosperm, the starchy food that feeds the developing seed. The ovary enlarges (E) and becomes a fruit. Fertilization occurs when a sperm cell carried by the pollen tube unites with the egg. As the fertilized egg begins to develop into an embryonic plant, it produces a variety of hormones to stimulate the outer wall of the ovule to harden into a seedcoat, and tissues of the ovary enlarge into a fruit. The fruit may be a fleshy fruit, such as an apple, orange, tomato, or squash, or a dry fruit, such as an almond, walnut, wheat grain, or rice grain.

Part B. Morphology 1. Types of flower a. According to symmetry Symmetrical – the floral organs are the same in number. Actinomorphic – the floral parts are radially symmetrical, e.g. an imaginary line drawn through the middle along any plane will produce a mirror image of either side. Zygomorphic – bilaterally symmetrical, e.g. a longitudinal line drawn at the middle (antero-posterior plane) will produce a mirror image of the other. Asymmetrical – when there is variation from the standard number in one or more sets of organs. b. According to the presence or absence of floral parts Complete – when all four whorls, the calyx, corolla, gynoecium and androecium are present. Incomplete – when one or two of the whorls is/are lacking. Perfect or bisexual or hermaphrodite – when a flower contains both stamen and pistil. Imperfect or unisexual – if either the male or female reproductive organ is absent. Pistillate flowers - when only the pistil is present in a flower. Staminate flowers – when only the stamen is present. Review of flower parts Androecium – a collective term for the stamens or the male part of the flower. Calyx – a collective term for the sepals and is usually located next to the bracts, if the bracts are present. It is usually green in color. Corolla – the inner whorl in a flower, a collective term for the petals. Floral envelope – a collective term for the calyx and corolla. Gynoecium – a collective term for the pistils. Involucre – a collective term for the bracts, if present, it composes the outermost whorl in a flower. Nectary – a tissue that produces or contains nectar. Pedicel – the stalk of a single flower. Perianth – the collective term for the calyx and corolla especially when they are similar in appearance. Petal – an individual member of the corolla. It functions for the attraction of pollinating agents. These are usually conspicuous and brightly colored. Pistil – the female reproductive organ of the flower. It has the following parts: the ovary, which is the swollen basal portion. The ovary contains the ovules which after fertilization, become the seeds; the style, or the stalk of the pistil, and the stigma, the uppermost part of the pistil. The stigma receives the pollen grains during pollination.

Receptacle, torus, hypanthium or floral cup – the enlarged part of the pedicel where the floral parts are attached. This is a characteristic of hypogynous and perigenous flowers. Sepal – the individual member of the calyx. They form the whorl next to the involucre when present. Stamen – the male reproductive part of a flower. It consists of a stalk called filament that bears the anther at the tip. The anther bears the pollen grains. Tepal – an undifferentiated part of the perianth or a term to apply if the perianth parts are not differentiated into petal or sepal. c. According to insertion of the different floral parts relative to the position of the ovary. Epigynous – the sepals, petals and stamens are seemingly attached on top of an interior ovary. The floral parts are actually on the upper part of the hypanthium. Hypogynous – the calyx, petals and stamens are attached to the receptacle on the base of a superior ovary. Perigynous – the perianth and stamens are attached half-way to the ovary forming a cup-like structure called the hypanthium, or floral cup or receptacle. 2. Fusion of floral parts a. Adnate or adherent – when members of a set are more or less united with those of another set, e.g. stamen-petal b. Connate – when the same set of organs are fused or united, i.e. petal-petal c. Distinct or free – the floral parts are not in any way united or fused. d. Imbricate – when the sepals or petals overlap each other at their margins. e. Valvate – when the sepals or petals touch at their margins. f. Wanting – when a part is lacking or absent 2. Variation in the calyx a. Claw – the narrowed base in some sepals and petals. b. Distinct – the sepals are separate, not united. c. Nerve – these are the veins present in sepals, petals or bracts. d. Pappus – these are bristle or scales in some fruits which represents the persistent calyx. e. Polysepalous or chorisepalous – when the sepals are free or separate f. Scabrous – when sepals are rough to the touch g. Tubular – when the sepals are united except at the toothed margins. 3. Variation in the corolla a. Apetalous – without petals; sometimes the petals are reduced into inconspicuous scales. b. Bilabiate – when the united corolla becomes two-lipped at the rim. c. Campanulate – when the united corolla assumes the shape of a bell. d. Funnel-shaped or funnelform – when the corolla tube gradually expands upward like that of a funnel.

e. Gamopetalous or sympetalous – when the petals are united at their margins forming a corolla tube. Parts of gamopetalous flower Corolla tube – the contracted part of the flower Corolla limb or corolla lobe – the expanded part of a petal; this term may also refer to the expanded part of a sympetalous corolla. Throat – the junction between the tube and corolla lobe. f. Ligulate or strap-shaped – (this term is usually applied to family Asteraceae), the base of a short tube opening out into an elongated, flat, strap-like appendage. g. Ligule – a flattened part of a ray corolla. h. Lip – these are projections in a two-lipped or bilabiate corolla of an irregular flower. i. Papilionaceous – irregular flowers of family Fabaceae. The shape resembles that of a butterfly.

j. k. l. m. n. o. p. q.

Parts of a papilionaceous flower Keel – the 2 lower petals and usually smaller petals. Standard or vexillum – the largest upper and outer petal. Wings – the two lateral petals. Plicate – when the petals are folded in longitudinal plaits. Polypetalous or choripetalous – when the petals are distinct or free. Rotate or stellate – the petals are wheel-shaped; the lobes radiate from the base. Salvershape – the corolla tube is elongated and the short corolla limb spreads horizontally. Spur – a protruding structure of the corolla or calyx. Tubular – when the corolla tube is elongated, the size is almost uniform throughout the tube. Urceolate – when the corolla is shaped like an arm.

4. Variation in the androecium a. Androecium – the stalk of a group of stamens b. Anemophilous – these are wind-pollinated plants. c. Basifixed – when the anther is attached to the base. d. Connective – the part of the stamen that connects two pollen sacs in the anther. e. Diadelphous – when the filaments of several anthers are united into 2 clusters. f. Diandrous –having two stamens. g. Didynamous – when there are four stamens present, the two pairs are of unequal length. h. Dordifixed – when the filament appears to be attached to the side or back of the anther. i. Entomophilous – when the flower is insect-pollinated. j. Epipetalous – when the stamens are attached to the petals k. Exserted – when the stamens extend beyond the perianth.

l. Extrorse – when the anther is turned outward, i.e. the anther faces the periphery of the flower m. Filament – the stalk of the anther n. Included – when the stamens are confined inside the corolla o. Introrse – when the stamens are turned inward, e.g. the stamens facing the center. p. Monadelphous – the stamens are united by their filaments. q. Monandrous – having one stamen. r. Pollinium – a mass of waxy pollen grains. This is a characteristic of most orchids. s. Sessile – when the filament is absent. t. Staminal column or tube – when the filaments are united forming a tube. u. Staminode – a sterile stamen, it may be reduced in size. v. Syngenacious – when the anthers are united and the filaments are free. w. Tetradynamous – when there are six stamens, the two are shorter than the four stamens. x. Versatile – when the anther is attached near the middle to the tip of the filament. 5. Variation in the gynoecium a. Androgynophore – a common stalk supporting the androecium and gynoecium. b. Apocarpous – one of more separate pistils. c. Carpel – a simple pistil. d. Cell or lucule – a hollow cavity; it also refers to the chambers in an ovary. e. Compound pistil – when two or more pistils are united. f. Funiculus – the stalk of the ovule. g. Gynophore – an enlarged stalk which bears the pistil. h. Half-superior/half inferior ovary – when the floral parts are attached midway on the ovary. i. Inferior ovary – when all the floral parts are attached above the ovary. j. Micropyle – the minute opening in the ovule where the pollen tube enters during fertilization. k. Nucellus – a region around the embryo sac, the latter commonly called the megasporangium. l. Ovary – the expanded basal part of the pistil that contains the ovules. m. Ovule – these are rounded structures inside the ovary which becomes the seeds after fertilization. n. Placenta – a part of the ovary where the ovules are attached. o. Polycarpous – having many carpels. p. Polygynous – having many pistils or styles. q. Sessile – when the style is wanting or absent. r. Septum (septa) – the interior walls separating the locules into two or more – loculed ovary. s. Simple pistil – a pistil with one-celled ovary bearing a single ovule or row of ovules. t. Stigma – the anterior most part of the pistil that receives the pollen.

u. Style – the stalk of the pistil. v. Superior ovary – when the floral parts are attached below the ovary. w. Syncarpous – a compound pistil. 6. Variation in the ovule a. Amphitropous or half-inverted – an ovule that is half-inverted; when the developing ovule turns 90 degrees on its funiculus. b. Anatropous or inverted – an ovule that is inverted, the ovule has turned 180 degrees during its development so that the micropyle is situated next to the funiculus. c. Campylotropous or incurved – when the ovule is curved and the micropyle nearly meets the funiculus. d. Orthotropous or straight – an ovule that is straight and erect. 7. Types of placentation – placentation is the arrangement of the ovules in the ovary. There are five main kinds of placentation although there may be variation of the five types. a. Axile – when the ovules are attached to the center or axis of the ovary, the locules from several to many. b. Basal – when the central stalk is absent and the ovules are attached at the basal part or floor of the ovary, the ovary has one locule or unilocular. c. Free-c...