Plants II: Gymnosperms and Angiosperms

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Plants II: Gymnosperms and Angiosperms
2012-02-27 15:23:14
Bio 244 lab

Unit 13
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  1. Gymnosperms
    • naked seed plants
    • wind-pollinated trees, shrubs
    • monoecious
    • Divisions:
    • *Coniferophyta (conifers, pines, relatives; ex Pinus)
    • *Cycadophyta (the cycads)
    • *Ginkgophyta (Ginkgo only included plant)
    • *Gnetophyta (the genetophytes)
  2. Angiosperms
    • flowering plants
    • seeds have a casing (ovary-->fruit)
    • all are in the division Anthophyta
    • two types:
    • *Moncotyledonae (monocots)
    • *Dicotyledonae (dicots)
  3. monoecious
    unisexual male and female reproductive structures on different parts of the same plant
  4. homospory
    • produce one type of spore that gives rise to a gametophyte via mitosis
    • bryophytes and primitive vascular seedless plants
  5. heterospory
    • two different kinds of spores are produced, which differ in size
    • megaspores (large spores) give rise to female gametophytes
    • microspores (small spores) give rise to male gametophytes
  6. Leaves of a typical pine tree are usually needle-like and occur in fascicles (groups) of...
    ...1-8 leaves.
  7. microsporangiate cones (pollen cones)
    • clusters on the lower branches of a tree
    • consists of a central axis with hundreds of microsporophylls arranged in tight spirals
    • microsproangia - consists of a wall and the enclosed microspore mother cells; pairs on each microsporophyll
    • microspore mother cell undergoes meiosis and produces four haploid microspores --> each develops into a winged pollen grain
  8. pollen grain
    • made of four cells: two prothallial cells, a tube cell, a generative cell
    • the prothallial cells degenerate
    • tube cell --> pollen tube
    • generative cell undergoes mitosis to produce two new cells: sterile cell and spermatogenous cell --> spermatogenous cell undergoes mitosis to produce two sperm
  9. megasporangiate cone (i.e. ovulate cones, seed cones, female strobili)
    • upper branches of tree
    • require 18-24 months to reach maturity
    • consists of a central axis and spirally arranged scales (two ovules are borne on each scale)
    • ovule consists of: an integument, an enclosed megasporangium (nucellus) containing a megaspore mother cell (megasporocyte)
    • megasporocyte undergoes meiosis --> linear tetrad of megaspores --> three megaspores degenerate --> one megaspore undergoes mitosis --> forms multicellular female gametophyte (megagametophyte) --> 2+ archegonia produced at micropylar end of the megagametophyte, each with a functional egg
  10. development of the megagametophyte:
    • occurs simultaneously with the growth of the pllen tube through the megasporangial tissue
    • fertilzation occurs a year after pollination
    • fusion forms the diploid zygote --> undergoes mitosis to produce a new sporophyte embryo
    • energy for initial growth supplied by stored energy in the nucellus
  11. three distinct plant generations are represented in a pine seed:
    • seed coat - derived from the integuments of the parent sporophyte generation
    • remnants of the female gametophyte forms a nutritive food supply
    • within the remnants of the female gametophyte is the new diploid sporophyte embryo
    • (2 sporophyte, 1 gametophyte)
  12. parts of a flower:
    • flower - aggregation of specialized leaves arranged on a stem of determinate growth
    • possesses 4 whorls of these leaves
    • all attach to a stem at a site called the receptacle
    • from out to in: sepals(calyx) --> petals(corolla) --> stamens(androecium) --> carpels(gynoecium)
    • pistil, receptacle
  13. sepals
    • collectively called calyx
    • often green and leaf-like in appearance
    • enclose the other floral parts while the flower is still in the bud stage
  14. petals
    • collectively called the corolla
    • colored and conspicuous
  15. perianth
    collective name for calyx + corolla
  16. stamens
    • collectively called the androecium
    • highly modified microsporophylls
    • consists of a filament (stalk) and an anther
  17. anther (of stamens)
    • pollen-producing part
    • made up of 4 fused microsporangia
  18. carpels
    • collectively called the gynoecium
    • highly modified megasporophylls
    • each carpel encloses 1+ ovule
  19. pistil
    • may consist of 1+ carpels
    • three distinct parts: stigma, style, ovary
  20. receptacle
    enlarged portion of a stem that all flower parts are attached to
  21. complete flower
    all four whorls of floral parts are present
  22. incomplete flower
    a flower is lack 1+ of the whorls
  23. perfect flower
    if both stamens and carpels are present
  24. imperfect flower
    lacks either a stamen (carpellate) or carpels (staminate)
  25. dioecious
    staminate flowers are produced on one individual plant and carpellate flwoers on another individual
  26. regular/actinomorphic floral symmetry
    radially symmetrical
  27. irregular/zygomorphic floral symmetry
    bilaterally symmetrical
  28. cotyledons
    embryonic leaves
  29. monocotyledoneae (monocots)
    • one cotyledon
    • floral parts occurring in threes/mults of three
    • leaf veins are parallel
    • vascular bundles scarred through the stem
    • fibrous roots
  30. dicotyledoneae (dicots)
    • two cotyledons
    • floral parts occurs in 4-5/mults of 4-5
    • leaf veins form net-like patterns
    • vascular bundles arranged in a ring
    • taproots
    • technically a polyphyletic group
  31. microsproangia (in angiosperm gametophytes)
    • microspore mother cells undergo meiosis --> forming tetrads of haploid microspores --> each microspore divides mitotically --> forming a two-celled immature male gametophyte (pollen grains)
    • one nucleus --> tube cell nucleus
    • other nucleus --> generative cell nucleus, which divides mitotically to produce two sperm that do not have flagella (haploid nuclei)
  32. megasporangia (in angiosperm gametophytes)
    • 2 rows of ovules
    • each ovule consits of two integuments and the enclosed megasporangium
    • megaspore mother cell divides meiotically and gives rise to 4 megaspores --> 3 degenerate --> remaining megaspore undergoes three rounds of mitosis --> embryonic sac containing 8 haploid nuclei
  33. embryo sac (of angiosperm gametophytes)
    • 8 haploid nuclei
    • only 1 nucleus is the egg nucleus
    • megagametophyte - mature embryo sac
    • lacks distinct archegonia
  34. double fertilzation
    • one sperm nucleus fuses with the egg nucleus, thus restoring the diploid stage in the life cycle --> resulting zygote develops into an embryo
    • second sperm nucleus fuses with two polar nuclei within the embryo sac --> triploid endosperm tissue
  35. fruit
    • ripened ovary
    • the receptacle or other parts of the flower, along with the carpels, may sometimes make up the fruit
    • two types of fruits: dry and fleshy
    • distinction between the types depends on the wall of the fruit (pericarp)
  36. fleshy fruits
    • moist at maturity
    • three types:
    • *simple fruit
    • *aggregate fruit
    • *multiple fruit
  37. dry fruits
    • made of one ovary, with no fleshy materials
    • little pericarp present
    • two types:
    • *fruit that split when mature
    • *fruits that don't split when mature
  38. seed
    • ripened ovule
    • contains an embryo
    • external part of the seed consists of the seed coat
    • internal parts consist of the embryo, the endosperm, any remaining megasporangial tissues
  39. hilium
    scar formed by the abscission of the short stalk by which the seed is attached to the periderm
  40. simple fruits
    • derived from a single ovary that may consists of a single carpel or a number of fused carpels
    • three types:
    • *drupe - one seed surrounded by a hard outer covering (ex olives, cherries, peaches, coconuts)
    • *berries - ovary with many seeds (ex tomatoes, green peppers, grapes, lemons, limes, waterleon, cucumber, squashes, pumpkins)
    • *pomes - develop in part from the surrounding flower tissues, particularly the receptacle (ex apples, pears)
  41. aggregate fruits
    • derived from a gynoecium consisting of a number of unfused carpels
    • numerous distinct unicarpellate pistils of a single flower
    • ex: strawberries, blackberries, raspberries
  42. multiple fruit
    • derived from the fused ovaries of many flowers
    • ex: pineapples, figs
  43. fruits that split when mature (dry fruit type)
    • two types:
    • *legume - one cavity that splits along both sides of the ovary (ex beans)
    • *capsule - ovary consisting of several cavities containing seeds (ex lilies, irises)
  44. fruits that do not split when mature (dry fruit type)
    • four types:
    • *achene - thin pericarp, one seed; ovary wall and seed coat are fused together; seed attached to pericarp only at base (ex sunflowers)
    • *caryopsis - single seeds, fully attached to a thin pericarp (ex wheat, rice, corn, other cereal grains)
    • *samaras - winged seeds (ex maples, ashes, elms)
    • *nut - thick pericarp, ovary wall is separated from the seed (ex hickories, walnuyts, oaks, pecans)