Introduction to the Angiosperms

Topics: Pollen, Flower, Ovule Pages: 5 (1124 words) Published: April 5, 2011
Chapter 19 – Introduction to the Angiosperms
I. Diversity in the Phylum Anthophyta
II. The Flower
a. The flower is a determinate shoot – that is, a shoot with the growth of a limited ruation, that bears sporophylls, which are sporangium-bearing leaves b. Carpel
* Contains the ovules, which develop into seeds after fertilization * The Vessel
c. Inflorescense
* Flowers that may be clustered in various ways into aggregations d. Pedicel
* The stalk of an individual flower in an inflorescense
1. The Flower Consists of Sterile and Fertile, or Reproductive, Parts Borne on the Receptacle a. Many flowers include two sets of sterile appendages, the sepals and petals, which are attached to the receptable below the fertile parts of the flower, the steamns and the carpels b. Sepals

* Attached to the receptacle below the fertile parts of the flower c. Androecium
* Microsporophylls
* House of man
d. Gynoecium
* The carpels, house of women
* Megasporophylls that are folwed lengthwise enclosing one or more ovules e. Stigma
* Receives the pollen
f. Ovary
* Enclosed the ovules
2. The Ovules Are Attached to the Ovary Wall at the Placenta a. Placenta
* The portion of the ovary where the ovules originate and to which they remain attached until maturity b. Placentation
* The arrangement of the placentae
* Consequently of the ovules varies among different groups of flowering plants 3. There Are Many Variations in Flower Structure
a. Perfect- The majority of flowers include both stamens and carpels b. Imperfect - If either stamens or carpels are missing
c. Staminate- Depending on the part that is present
d. Carpellate
e. Monoecious- If both staminate and carpellate flowers occur on the same plant as in maize and the oaks f. Dioecious
* If the staminate and carpellate flowers are found on separate plants * As in the willows and hemp
g. Hypogynous
* In terms of their points of insertion, the perianth and stamens are said to be it * When situated on the receptacle beneath the ovar and free from it and from the calyx h. Epigynous
* Arising from the top of the ovary
i. Perigynous
* With the stamens and petals adnate to the calyx and thus forming a short tube arising from the base of the ovary j. Regular
* Tulips
* In some flowers the members of the different whorls of the flower are made up of members of similar shape that radiate from the center of the flower and are equidistant from each other * They are radially symmetrical

k. Irregular
* Bilaterally symmetrical flowers
* snapdragons
III. The Angiosperm Life Cycle
1. Microsporogenesis and Microgametogenesis Culminate in the Formation of Sperm a. Sporogenous
* Cells become discernible within the anther
b. Tapetum
* The innermost layer of the pollen sac wall
c. Tube cell
2. Megasporogenesis and Megagametogenesis Culminate in formation of an Egg and Polar Nuclei a. Funiculus
* The ovule is a relatively complex structure consisting of the salk * Bearing a nucleus enclowed by one or two integruments
b. Chalazal
* at the end of the third mitotic division, the eight nuclei are arranged in two groups of four, one group near the micropylar end of the megagametophyte and the other at the opposite end c. Polar nuclei

* One nucleus from each group migrates into the center of the eight nuclearte cell * These two nuclei are then called polar nuclei
d. Embryo sac
* The eight nucleate seven celled structure is the mature female gametophyte 3. Pollination and Double Fertilization in Angiosperms are Unique a. Dehiscence
* Shedding of its contents
b. Pollination - The process where by this transfer occurs; The pollen grains are transferred to the stigmas in a variety of ways c. Stigmatic tissue
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