Biology – 328 Lab Plants and People

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

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

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)

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

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

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

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

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

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

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

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

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

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

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

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.

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?

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