Plants II: Gymnosperms and Angiosperms

• 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)

• flowering plants
• seeds have a casing (ovary-->fruit)
• all are in the division Anthophyta
• two types:
• *Moncotyledonae (monocots)
• *Dicotyledonae (dicots)

unisexual male and female reproductive structures on different parts of the same plant

• produce one type of spore that gives rise to a gametophyte via mitosis
• bryophytes and primitive vascular seedless plants

• 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

...1-8 leaves.

• 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

• 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

• 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

• 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

• 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)

• 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

• collectively called calyx
• often green and leaf-like in appearance
• enclose the other floral parts while the flower is still in the bud stage

• collectively called the corolla
• colored and conspicuous

collective name for calyx + corolla

• collectively called the androecium
• highly modified microsporophylls
• consists of a filament (stalk) and an anther

• pollen-producing part
• made up of 4 fused microsporangia

• collectively called the gynoecium
• highly modified megasporophylls
• each carpel encloses 1+ ovule

• may consist of 1+ carpels
• three distinct parts: stigma, style, ovary

enlarged portion of a stem that all flower parts are attached to

all four whorls of floral parts are present

a flower is lack 1+ of the whorls

if both stamens and carpels are present

lacks either a stamen (carpellate) or carpels (staminate)

staminate flowers are produced on one individual plant and carpellate flwoers on another individual

radially symmetrical

bilaterally symmetrical

embryonic leaves

• one cotyledon
• floral parts occurring in threes/mults of three
• leaf veins are parallel
• vascular bundles scarred through the stem
• fibrous roots

• 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

• 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)

• 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

• 8 haploid nuclei
• only 1 nucleus is the egg nucleus
• megagametophyte - mature embryo sac
• lacks distinct archegonia

• 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

• 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)

• moist at maturity
• three types:
• *simple fruit
• *aggregate fruit
• *multiple fruit

• 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

• 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

scar formed by the abscission of the short stalk by which the seed is attached to the periderm

• 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)

• derived from a gynoecium consisting of a number of unfused carpels
• numerous distinct unicarpellate pistils of a single flower
• ex: strawberries, blackberries, raspberries

• derived from the fused ovaries of many flowers
• ex: pineapples, figs

• 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)

• 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)