Plant Morphology: Types of Stem Modifications
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Questions and Answers

What is the characteristic feature of a sucker?

  • Horizontally growing underground stem
  • Lateral branch with short internode and each node bearing a rossette of leaves and tuft of roots at base
  • Main stem growing in the soil horizontally and branches developing obliquely from nodes above the soil (correct)
  • Reduced stem with disc-like structure and numerous fleshy scaly leaves

    • What is the function of underground stem modifications?

  • Food storage and vegetative propagation (correct)
  • Supporting the plant above ground
  • Protecting the plant from herbivores
  • Conducting water and minerals to the plant

    • What is a rhizome?

  • A fleshy and horizontally growing stem found below the soil surface (correct)
  • A type of leaf modification
  • A type of root
  • A type of stem modification found above ground

    • What is a corm?

    <p>A condensed structure that grows vertically under the soil surface</p> Signup and view all the answers

    What is the purpose of the 'eyes' found on tubers?

    <p>To serve as axillary buds</p> Signup and view all the answers

    What is a phylloclade?

    <p>A green, photosynthetic, flattened or rounded succulent stem</p> Signup and view all the answers

    What is an offset?

    <p>A lateral branch with short internode and each node bearing a rossette of leaves and tuft of roots at base</p> Signup and view all the answers

    What is a characteristic feature of a bulb?

    <p>Has a disc-like structure and numerous fleshy scaly leaves</p> Signup and view all the answers

    What type of inflorescence has florets that may be unisexual, bisexual, and sterile?

    <p>Heterogamous</p> Signup and view all the answers

    What is the term used to describe an inflorescence with a branched peduncle, where each branch bears a spike?

    <p>Spike of spikelet</p> Signup and view all the answers

    What is the characteristic feature of Asteraceae family?

    <p>Heterogamous inflorescence</p> Signup and view all the answers

    What is the type of cyme where the peduncle ends in a flower and from the base of it many lateral branches arise?

    <p>Multiparous cyme</p> Signup and view all the answers

    In a catkin, what is the peduncle like?

    <p>Thin, long, and weak</p> Signup and view all the answers

    What is the arrangement of flowers in a cyme called?

    <p>Basipetal succession</p> Signup and view all the answers

    What is the term used to describe an inflorescence with a thick, long, and fleshy peduncle?

    <p>Spadix</p> Signup and view all the answers

    What type of cyme has lateral branches that develop on the same side of the peduncle?

    <p>Helicoid cyme</p> Signup and view all the answers

    In a corymb, what is the arrangement of flowers?

    <p>All flowers are present at the same level</p> Signup and view all the answers

    What is the term used to describe an inflorescence with a branched peduncle, where each branch has a flower cluster?

    <p>Compound corymb</p> Signup and view all the answers

    What type of cyme has lateral branches that develop alternately on left and right side of the peduncle?

    <p>Scorpioid cyme</p> Signup and view all the answers

    Which of the following is an example of a heterogamous inflorescence?

    <p>Sunflower</p> Signup and view all the answers

    In an umbel, what is the arrangement of flower stalks?

    <p>Flower stalks are of more or less equal length</p> Signup and view all the answers

    What surrounds a heterogamous inflorescence?

    <p>Involucre</p> Signup and view all the answers

    What is the term used to describe an inflorescence with a branched peduncle, where each branch has a flower cluster, in plants like coriander?

    <p>Compound umbel</p> Signup and view all the answers

    What is the term used to describe an inflorescence with a retarded and broad peduncle?

    <p>Capitulum</p> Signup and view all the answers

    What is the term used to describe a leaf having more than four leaflets?

    <p>Multifoliate palmate compound leaf</p> Signup and view all the answers

    What type of phyllotaxy is characterized by a single leaf arising at each node?

    <p>Alternate or spiral</p> Signup and view all the answers

    Which of the following types of heterophylly is due to aquatic adaptation?

    <p>Environmental Heterophylly</p> Signup and view all the answers

    What is the term used to describe a leaf that is modified into a thin thread-like structure?

    <p>Leaf tendril</p> Signup and view all the answers

    Which of the following plants exhibits decussate phyllotaxy?

    <p>Calotropis</p> Signup and view all the answers

    What is the term used to describe the occurrence of more than one type of leaves on the same plant?

    <p>Heterophylly</p> Signup and view all the answers

    Which of the following plants exhibits habitual heterophylly?

    <p>Artocarpus</p> Signup and view all the answers

    What is the term used to describe a leaflet that is modified into a tendril-like structure?

    <p>Leaflet tendril</p> Signup and view all the answers

    What type of androecium is found in Cotton, Hollyhock, and Ladyfinger?

    <p>Monoadelphous</p> Signup and view all the answers

    In which type of cohesion are anthers as well as filaments of stamens united through their whole length?

    <p>Synandrous</p> Signup and view all the answers

    What is the term for when stamens are attached to petals?

    <p>Epipetalous</p> Signup and view all the answers

    In which type of cohesion are filaments united into more than two bundles?

    <p>Polyadelphous</p> Signup and view all the answers

    What is the term for when stamens are attached to tepals?

    <p>Epiphyllous</p> Signup and view all the answers

    In which type of cohesion are anthers united in a bundle but filaments remain free?

    <p>Syngenesious</p> Signup and view all the answers

    What is the term for when the floral parts of similar whorl are fused?

    <p>Cohesion</p> Signup and view all the answers

    When the stamens of an androecium are free from one another, it is called what?

    <p>Polyandrous</p> Signup and view all the answers

    Study Notes

    Plant Morphology

    Underground Stem Modifications

    • Sucker: a stem that grows horizontally in the soil, with branches developing obliquely from nodes above the soil (e.g., Mint, Pineapple, Chrysanthemum)
    • Offset: a lateral branch with short internodes, each node bearing a rossette of leaves and a tuft of roots at the base (e.g., Pistia, Eichhornia)
    • Tuber: the tip of an underground branch that becomes swollen in the soil, with eyes (axillary buds) covered by scaly leaves (e.g., Potato, Helianthus tuberosus)
    • Rhizome: a fleshy, horizontally-growing stem found below the soil surface, with small nodes and internodes covered by scaly leaves (e.g., Ginger, Turmeric, Canna, Water lily, Banana)
    • Corm: a condensed structure that grows vertically under the soil surface, with spherical nodes and internodes (e.g., Colocasia, Alocasia, Zaminkand, Saffron, Gladiolus, Colchicum)
    • Bulb: a stem that is reduced and has a disc-like structure, surrounded by numerous fleshy, scaly leaves; many roots arise from its base (e.g., Onion, Garlic)

    Special Stem Modifications

    • Phylloclade: a green, photosynthetic, flattened or rounded succulent stem with leaves that are either feebly developed or modified into spines (e.g., Opuntia, Casuarina, Euphorbia, Cactus)
    • Thorn: a modification of an axillary bud (e.g., Bougainvillea, Duranta, Carissa)

    Phyllotaxy

    • Alternate or spiral: single leaf arising at each node (e.g., Cyperus rotandus, Chinarose, Mustard, Sunflower)
    • Opposite: leaves occurring in pairs at each node
      • Decussate: leaves that stand at right angles to the next upper or lower pair (e.g., Calotropis, Mussaenda)
      • Superposed: successive pairs of leaves standing directly over a pair in the same plane (e.g., Psidium, Ixora)
    • Whorled: more than two leaves at each node (e.g., Nerium, Alstonia)

    Heterophylly

    • Developmental Heterophylly: leaves of different forms and shapes occur at different periods or places on the same plant (e.g., Mustard, Sonchus, Eucalyptus)
    • Environmental Heterophylly: an aquatic adaptation commonly found in rooted emergent hydrophytes, where submerged leaves differ from floating and aerial leaves (e.g., Limnophila, Heterophylla, Ranunculus aquatiles, Sagittaria)
    • Habitual Heterophylly: due to habit, mature leaves differ in their shape and incisions (e.g., Artocarpus, Jack fruit)

    Modifications of Leaves

    • Leaf Tendril: a whole leaf modified into a thin, thread-like structure (e.g., Lathyrus aphaca, Wild pea)
    • Leaflet Tendril: a leaflet modified into a tendril-like structure (e.g., Pisum sativum, Garden pea, Lathyrus odoratus, Sweet pea)
    • Leaf Spine: leaves or any part of a leaflet modified into a pointed spine (e.g., Achyranthes)

    Inflorescence

    • Spike: an inflorescence with a peduncle that is branched and each branch bears a spikelet (e.g., Family Gramineae)
    • Catkin: an inflorescence with a thin, long, and weak peduncle, with flowers that are sessile and unisexual (e.g., Mulberry, Betula, Oak)
    • Spadix: an inflorescence with a thick, long, and fleshy peduncle, with small sessile and unisexual male and female flowers covered by one or more green or colorful bracts (e.g., Colocasia, Maize, Aroids, Palms)
    • Corymb: an inflorescence with a short peduncle and all flowers present at the same level, due to the lower flower having a longer pedicel than the upper one (e.g., Candytuft, Iberis amara)
    • Umbel: an inflorescence with flower stalks of different lengths, arising from the same point, with a whorl of bracts forming the involucre (e.g., Centella)
    • Capitulum / Racemose Head: an inflorescence with a broad, flattened, or concave peduncle, with small flowers arranged on it (e.g., Sunflower, Zinnia, Marigold, Cosmos)

    Cymose Inflorescence

    • Uniparous Cyme / Monochasial Cyme: an inflorescence with a peduncle that terminates in a flower, producing a lateral branch at a time (e.g., Heliotropium, Saraca, Atropa, Datura)
    • Dichasial or Biparous Cyme: an inflorescence with a peduncle that ends in a flower, from which two lateral branches arise, which also terminate in flowers (e.g., Bougainvillea, Jasmine, Teak, Mirabilis, Dianthus, Nyctanthes)
    • Multiparous Cyme / Polychasial: an inflorescence with a peduncle that ends in a flower, from which many lateral branches arise, which also terminate in flowers (e.g., Michelia, Champa, Magnolia)

    Stamens

    • Basifixed: filament attached to anther by its base (e.g., Datura, Radish, Mustard)
    • Dorsifixed: filament attached to the back of the anther (e.g., Passion flower)
    • Versatile: filament attached to the back of the anther at a point only, allowing the anther to swing freely (e.g., Wheat, Grass, Maize)

    Cohesion of Stamens

    • Adelphous: when stamens are united by their filaments only (e.g., Cotton, Hollyhock, Ladyfinger)
    • Diadelphous: when filaments are united in two bundles, but anthers remain free (e.g., Gram, Pea, Bean)
    • Polyadelphous: when filaments are united into more than two bundles (e.g., Citrus, Castor)
    • Synandrous: when anthers as well as filaments of stamens are united through their whole length (e.g., Colocasia, Alocasia, Momordica, Cucurbitaceae family)
    • Syngenesious: when only anthers are united in a bundle, but filaments remain free (e.g., Compositae family)

    Adhesion of Stamens

    • Epipetalous: when stamens are attached to petals (e.g., Brinjal, Datura, Tobacco, Sunflower, Potato)
    • Epiphyllous: when stamens are attached to tepals (e.g., Onion, Lily)

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    Description

    This quiz covers different types of stem modifications, such as suckers and offsets, with examples of plants that exhibit these characteristics.

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