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Biology – 328 Lab

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  1. Biology – 328 Lab Plants and People

  2. Objective • Understanding origin of flowers, its morphology and anatomy • To study flowers based on • Types of pollination • Presence of floral whorls • Presence of sexes • Line of symmetry • Sexual expression • Position of ovary • To study different types of inflorescences

  3. Background • Origin – Modified shoot • Floral Morphology • Calyx (sepals) • Corolla (petals) - 3’s in monocots and 4’s or 5’s in dicots) • Perianth (calyx + corolla) • Gynoecium (pistil- stigma, style, ovary) • Androecium (stamen- anther, filament) • Receptacle

  4. Floral anatomy • Locules – Open space inside ovary • Carpels – Basic developmental unit • Apocarpous (carpels not fused) • Syncarpous (carpels fused) • Pistil • Simple – Unicarpellate (1 carpel) • Compound – Syncarpellate (2 or more carpels FUSED)

  5. Types of flowers • Based on pollination • Entomophily (insect) • Anemophily (wind) • Based on presence of floral whorls • Complete flower - All 4 floral whorls present • Incomplete – Not all 4 floral whorls present • Based on presence of sexes • Perfect – Both sexes present • Imperfect – Not both sexes present

  6. Based on line of symmetry • Actinomorphic (regular)– more than one plane of symmetry • Zygomorphic (irregular)– One plane of symmetry • Based on sexual expression • Monoecious – “One house” (male and female part present in the same flower in the same plant or different flowers in the same plant) • Dioecious – “Two house” (male and female flowers in different flowers in different plants

  7. Based on ovary position • Hypogynous (superior ovary) – Floral whorls arranged below (=hypo) ovary (=gynous)

  8. Epigynous (Inferior ovary) – Floral whorls arranged above (epi) ovary (=gynous)

  9. Perigynous (superior ovary) – Floral whorls arranged around (=peri) overy (=gynous). Presence of well developed HYPANTHIUM (cup) made of receptacle and bases of sepals, petals and stamen

  10. Types of inflorescences • Raceme – Unbranched inflo. with pedicel and indeterminate (young flowers on top). Eg. Orchid, Milkwort

  11. Spike – Same as receme but no pedicel (sessile flowers) Eg. Gladious, Hyacinth

  12. Catkin/Ament - Same as spike, but unisexual Eg. Oak, Pecan, Birch, hickory, willow

  13. Umbel – All pedicels arise from a common point Eg. Onion, Garlic

  14. Compound Umbel – Group of umbels whose peduncles arise from same point Eg. All members of Apiaceae (carrot family) • Panicle – Inflorescence which branches and rebranches. For eg. Yucca, Lilac, Wisteria

  15. Head/Capitulum – Dense arrangement of sessile flowers on a common receptacle Eg. Sunflower, Daisy, Aster, Thistle

  16. Today’s Lab • Carefully EXAMINE all floral material provided using the following exercise and questions as a guideline.  To gain an ultimate familiarity with floral morphology, compare the material against descriptions and definitions in your lecture notes or textbook.  Become familiar with cross and long sections. • 1.  Flowers are arranged in groups called inflorescences.  We will examine some inflorescences particular to certain families later in the semester.  For now, know what an inflorescence is and which one we looked at today. • 2.  DRAW a longitudinal section of a typical flower labeling the following parts:  receptacle, calyx, sepals, corolla, petals, perianth, pedicel, ovary, ovule, style, stigma, pistil, gynoecium, anther, filament, stamen, and androecium.

  17. Today’s Lab • 3.  EXAMINE by dissection the floral material provided making long and cross sections of the flower and its parts.  On a separate sheet of paper, SKETCH the flowers and label the parts.  Then, FOR EACH FLOWER, answer the following questions: • Is the flower actinomorphic (regular) or zygomorphic (irregular)? • How many sepals are present?  Petals?  Stamens?  Carpels?  To count carpels, count the style branches and/or count the zones of placentation by cross- sectioning the ovary. • Is the ovary inferior or superior? • Is the flower from a monocotyledonous or dicotyledonous plant? • Is the flower perfect (both sexes present) or imperfect?  Complete (all four floral whorls) or incomplete?

  18. Summary Today’s Lab • Floral Origin, morphology and anatomy • Different types of flowers and inflorescence Next week’s lab – Fruits • Quiz on Flowers