Determinateindeterminate hypo under oral parts aached

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: reproduc�ve structures Placenta�on (fusion of carpels) Gynoecium ♀   Carpels (megasporophyll), 1-­‐many: –  Evolved from a leaf containing sporangia on its edges, leaf became curled to enclose the sporangia –  Simple, compound (fused) –  S�gma: receives the pollen –  Style: growth of pollen tube –  Ovary: encloses the ovules Placenta: part of ovary where ovules are a�ached –  Parietal (a) –  Axile (b) –  Free central (c) tomato cucumber hot pepper soap wort Ovary posi�on Inflorescence Hypogynous (superior ovary) Group or cluster of flowers arranged on a stem (peduncle), composed of a main branch or complicated arrangement of branches (stalk of each single flower is called a pedicel). –  determinate/indeterminate (hypo-: under) –  floral parts a�ached to receptacle, below and free from ovary Epigynous (inferior ovary) (epi-­‐: above) –  hypanthium fused with the ovary, floral parts above ovary Hypanthium (fused petal, sepal, stamen) Perigynous (superior ovary) (peri-­‐: around) –  hypanthium par�ally fused squash tulip 12 The angiosperm life cycle The angiosperm life cycle – alterna�on of genera�ons   Gametophytes are further reduced   Both antheridia and archegonia are lacking   Ovule develops into seed   Ovary develops into fruit The angiosperm life cycle Heteromorphic genera�ons The angiosperm life cycle Heteromorphic genera�ons 13 Forma�on of male gametophyte Forma�on of female gametophyte “Polygonum-­‐type”:   Single megasporocyte form within the ovule (1-­‐many ovules)   Divides into 4 haploid spores three of which die   Three mito�c divisions   Two groups of 4 nuclei each   One nucleus from each group migrate into center (central cell)   7-­‐celled (8-­‐nucleate) embryo sac (megagametophyte)   2 integuments   Microsporocytes develop within anthers   Each produces 4 haploid microspores (pollen grain)   Pollen grain develop a resistant outer wall (exine) and an inner wall (in�ne)   Each microspore divides into a tube cell and a genera�ve cell (2-­‐celled immature microgametophyte)   Genera�ve cell divide to form two sperm (3-­‐celled microgametophyte) (Figure 19-15) Pollina�on   Process by which pollen is transferred, enabling fer�liza�on   Interac�on between flower and vector   Abio�c vs. bio�c   Cross-­‐ vs. self-­‐pollina�on Double fer�liza�on   Pollen grains transferred to s�gma   Pollen tube grows down through s�gma to ovules   Enters ovule through micropyle   One sperm nucleus unites with egg cell, the other with central cell   Remaining nuclei degenerate   Fusion of sperm nucleus with polar nuclei results in (usually) triploid primary endosperm Nectar guides 14 Fruit development   Primary endosperm nucleus divides, forming the endosperm   Role of endosperm   Zygote develops into an embryo   Integuments develop into seed coat   Ovary wall (and other floral parts) develops into a fruit   Fruit encloses the seeds   Defining characteris�cs   Seed dispersal 15...
View Full Document

This note was uploaded on 02/25/2014 for the course BIO 318 taught by Professor Maryabisson during the Spring '11 term at SUNY Buffalo.

Ask a homework question - tutors are online