Biology Lab Manual (EN)

Exercise 11 Aim: Study and describe flowering plants of families Solanaceae, Fabaceae and Liliaceae. Principle: Taxonomy deals with identification, nomenclature and classification of organisms. Bentham and Hooker's system of classification is universally used for classification of plants. Field identification of plants is based primarily on morphological features particularly the floral characters. Requirement: Locally available plant specimens of Solanaceae, Fabaceae and Liliaceae. (minimum 3 species for each family other than the ones described for reference in the manual); each specimen should have at least a small branch with a few inter nodes, leaves, flowers and fruits; glass slides, cover glass, water, 100 ml beakers, petridish, razor, blade, needles, brush, hand lens, dissecting microscope and compound microscope. Keep the twigs in beakers containing water. Make yourself familiar with the terms given to describe the habit of plant, its root system, stem and leaf, inflorescence and flowers. Describe the vegetative and floral features of the plant in the same sequence using terms described therein. Observe the flower bud under dissection microscope or a hand lens and note the aestivation patterns of calyx and corolla, number of sepals and petals (tri, tetra, pentamerous), number of stamens. Cut LS of the flower, place it on a slide and observe under the dissecting microscope to study: • Position (attachment) of stamens – opposite/alternate to petals; free or epipetalous; extrorse/ introrse anthers (anther lobes in the bud face away from axis – extrorse; anther lobes in the bud face towards the main axis – introrse). • Number of carpels (mono, bi, tri- carpellary); Position of the ovary (epigynous, perigynous, hypogynous). Mount a stamen on a slide and study the attachment of filament to anther (basifixed, dorsifixed, versatile, adnate), dehiscence pattern of anther (porous, longitudinal), number of anther lobes (monothecous, dithecous). Mount the pistil and study the ovary, style and stigma. Also cut a TS of the ovary to study the number of locules and placentation. Write the floral formula and draw the floral diagram of each specimen based on the description. Identify features of the different parts of flower on the basis of descriptions given in Table 11.1. Compare the characters with those given in the table and identify the family to which the plant belongs to. Note: For ready reference some plants are described for each family. The students are required to study the plants other than one described here-under. Questions 1. Draw the floral diagram and write the floral formula from the below given description of a flower- Bisexual, actinomorphic, hypogynous, sepals 5, gamosepalous, petals 5, free, imbricate aestivation, stamens 6, arranged in 2 whorls, ovary superior, trilocular, axile placentation. 2. In which type of placentation would the ovary be always unilocular? 3. If a flower is epigynous what is the position of floral parts? 4. What in the fruit is equivalent to the ovule of the ovary? Laboratory Manual: Biology Table 11.1 Description of parts of flowers: Calyx/Corolla Aestivation Arrangement of sepals and petals with respect to one another Aestivation (i) Valvate: The sepals/peta ls close to each other without (Fig 11.1 a–e) overlapping or may be in contact with each other. (ii) Twisted: Overlapping is regular, i.e., one margin of the sepal/ petal overlap the next member and the other margin is overlapped by the previous. (iii) Imbricate: Out of five sepals/petals one is completely internal being overlapped on both margins and one is completely external with the rest of the members arranged as in twisted aestivation. (iv) Quincuncial: Out of five sepals/petals two are completely internal, two external and one has one margin external and the other margin internal. (v) Vexillary: Out of five sepals/petals the posterior one is the largest and external almost completely covering two lateral members which in turn overlap the two small anterior sepals/petals Number of stamens The number of stamens may vary from a few to many in different flowers Cohesion (Fig. 11.2 a-e) Stamens may be free or united. If united they can be of the following type: (i) Syngenesious: Filaments free and anthers united, e.g., Sunflower. (ii) Synandrous: Stamens fused all through their length. e.g., Cucurbita. (iii) Adelphous: Anthers remain free and filaments are united. Adelphous condition can be:(a) Monoadelphous - United to form 1 bundle. e.g., China rose. (b) Diadelphous - United to form 2 bundles. e.g., Pea. (c) Polyadelphous- United into more than two bundles. e.g., Lemon. Adhesion Fusion of stamens with other parts of the flower. (Fig. 11.3) (i) Epipetalous: Stamens fused with petals e.g., Sunflower, Datura. (ii) Epiphyllous: Stamens fused with perianth e.g., Lily. Attachment of filament to anther (Fig. 11.4 a-d) (i) Basifixed: Filament attached to the base of anther. e.g., Mustard. (ii) Adnate: Filament attached along the whole length of anther. e.g., Michelia, Magnolia. Exercise 11 (iii) (iv) Dorsifixed: Filament attached to the back of anther, e.g., Passion flower. Versatile: Anther lobes attached with filament in the middle portion with both ends free. e.g., Gramineae family. Lobes of anther (Fig. 11.5 a,b) (i) (ii) Monothecous: Anther single lobed. Dithecous: Anther bi-lobed. Dehiscence pattern (Fig. 11.6 a,b) (i) (ii) Porous: Pollens released through pores, e.g., brinjal, potato. Longitudinal: Pollens released through the longitudinal slit of anther lobes, e.g., China rose, cotton. Gynoecium Position of ovary (Fig. 11.7 a-d) Cohesion (Fig. 11.8 a-c) Number of locules in ovary Placentation (Fig. 11.9 a-e) (i) Epigynous: Position of ovary inferior to other floral parts. e.g., mustard, China rose. (ii) Perigynous: Other floral parts (organs) are attached around the ovary. e.g., apple, guava. (iii) Hypogynous: Position of ovary superior to other floral parts e.g., sunflower. If number of carpels is more than one, they may be (i) Apocarpous: Carpels are free. Each carpel has its own style and stigma. e.g., rose. (ii) Syncarpous: Carpels are united, e.g., lady finger, tomato. Vary from one to many (i) Unilocular: One locule, e.g., rose, pea. (ii) Bilocular: Two locules. e.g., datura. (iii) Multilocular: Many locules, e.g., lady’s finger, China rose. (i) Marginal: The placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge e.g., pea. (ii) Axile: The ovary is partitioned into several chambers or locules and the placentae are borne along the septa of the ovary. e.g., tomato, China rose. (iii) Parietal: The ovules develop on the inner wall of the ovary or on peripheral part. Ovary unilocular but in some cases becomes two chambered due to formation of a false septum. e.g., mustard. (iv) Free central: Ovules are borne on the central axis and septa are absent. e.g., carnation, chilly. (v) Basal: Placenta develops at the base of the ovary. e.g., sunflower. Laboratory Manual: Biology (b) (c) (a) (d) (e) Fig. 11.1 Aestivation (a) Valvate (b) Twisted (c) Imbricate (d) Quincuncial (e) Vexillary Fig. 11.2 Cohesion of stamens (a) Syngenesious (b) Synandrous (c) Monoadelphous (d) diadelphous (e) Polyadelphous (a) (b) (c) (d) Fig. 11.4 Attachment of filament to anther (a) Basifixed (b) Adnate (c) Dorsifixed (d) Versatile (a) (b) Fig. 11.5 Anther lobes (a) Dithecous (b) Monothecous Laboratory Manual: Biology (c) (d) (b) (a) Fig. 11.7 Position of ovary (a) Epigynous (b-c) Perigynous (d) Hypogynous (c) (a) (b) Fig. 11.8 Cohesion of carpels (a) Apocarpous (b-c) Syncarpous Laboratory Manual: Biology Annexure 1 Characteristics Solanumnigrum(Makoi, Petunia alba Lathyrus sp. Pisum sativum Asphodelustenuifolius Black night shade) HabitRootStemLeafInflorescence HerbaceousannualTap rootErect,herbaceous,branched, solid,cylindrical,greenEx-stipulate,petiolate orsessile, simple,alternate,reticulatevenationCymose HerbaceousannualTap rootErect,herbaceous,branched, solid,cylindrical, greenEx-stipulate,sessile, simple,alternate in thebasal parts andopposite decussatein upper parts,reticulate venationSolitary Herbaceous annual,climberTaproot, the lateralroots may havenodules whichcontain nitrogenfixing RhizobiumbacteriaWeak, cylindrical,branched,herbaceous, aerial,climbing with help ofleaf tendrils, greenStipulate (stipulesfoliaceous and inpairs), modified into atendril, simple,alternate, reticulatevenationRacemose Herbaceous annual,climberTaproot, the lateralroots may havenodules whichcontain nitrogenfixing RhizobiumbacteriaWeak, cylindrical,branched,herbaceous, aerialclimbing with help ofleaf tendrils, greenStipulate (stipuleslarge, ovate,foliaceous), petiolate,imparipinnatelycompound, (leaf lets 4or 6) the commonrachis ends in abranched tendril,terminal leaflet isalways a tendril;alternate leaflets withreticulate venationRacemose Herbaceous annualFibrous rootVery small butscape formed inreproductivephaseFistular, slenderRacemose Laboratory Manual: Biology Fig. 11.11 Lathyrus (a) A twig (b) LS of flower (c) Floral diagram Annexure 2 Other Examples Family : Solanaceae Family : Fabaceae Family : Liliaceae Physalis Solanum xanthocarpum Solanum melongena Solanum tuberosum Nicotiana tabacum Hyocyamus Atropa belladonna Withania somnifera Cestrum nocturnum Datura Phaseolus moong (Urad) P. vulgaris (Kidney bean, French bean) P. aureus (Moong) Trigonella (Fenugreek) Cajanus cajan (Arhar, pigeon pea) Dolichos lablab (Sem, Hyacinth bean) Cicer arietinum (chana, gram, chickpea Indigofera (Indigo) Abrus (Ratti) Arachis hypogea (groundnut) Medicago sativa (Alfalfa) Allium cepa (onion) Gloriosa superba Aloe barbendesis Heterosmilax Asparagus officinale Yucca gloriosa Lilium candidum Smilax spp IDENTIFICATION AND SYSTEMATIC POSITION- Family : Solanaceae 1. Leaves reticulate venation, flowers tetra or pentamerous, tap root system. Dicotyledons 2. Petals fused, Gamopetalae 3. Ovary superior, carpels usually two, stamens alternate with the corolla lobes, number of stamens equal or fewer to the number of corolla lobes. Bicarpellatae 4. Herbs or twiners, leaves alternate, flowers actinomorphic, stamens epipetalous, ovary superior two carpels, bilocular, axile placentation, ovules few or many in each carpel. Polemoniales 5. Herbs and shrubs, leaves simple, alternate, gamosepalous, stamens 5, epipetalous, ovary superior, bicarpellary syncarpous, bilocular, sometimes four locules due to false septum, many ovules in each locule, swollen placenta, ovary obliquely placed in the flower, axile placentation, fruit a berry or a capsule. Solanaceae IDENTIFICATION AND SYSTEMATIC POSITION - Family : Fabaceae 1. Leaves with reticulate venation, flowers tetra or pentamerous, tap Dicotyledons root system. 2. Petals free or not united. Polypetalae 3. Flowers hypo or perigynous; regular or irregular (vexillary). Calyciflorae 4. Flowers zygomorphic and papilionaceous, descending imbricate aestivation of corolla, 1 standard, 2 wings and 2 keels; Fabaceae stamens10, mono or diadelphous (9+1) ovary superior, marginal placentation, ovules many. IDENTIFICATION AND SYSTEMATIC POSITION - Family : Liliaceae 1. 2. 3. Leaves usually with parallel venation, flowers trimerous, fibrous root system, embryo with one cotyledon Ovary superior, trilocular, 6 tepals in 2 whorls of 3+3, petaloid Perianth petaloid, 6 tepals free or connate below. stamens 6 in two whorls of 3+3, opposite to tepals, epiphyllous, ovary tricarpellary, syncarpous, trilocular, 2 or more ovules per locule fruit 3 celled berry or capsule. Monocotyledonous Coronariae Liliaceae

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