Angiosperm Lecture Notes

Flashcards on Angiosperm Reproduction

Angiosperm

Vascular seed plants that have seeds enclosed in ovaries that mature into fruits.

Flower

The part of the 2n sporophyte plant and has male and/or female organs.

Development of Pollen Grains

Male 2n anthers contain 2n microsporangia which produce n microspores (by meiosis).

Development of Female Gametophyte

One cell becomes the n megaspore that forms the reduced female n gametophyte (via mitosis).

Pollination

A pollen grain lands on a carpel’s stigma and one n cell starts dividing to form a pollen tube that grows down the carpel’s style, through the micropyle opening of the carpel’s ovule. It discharges its two haploid sperm cells into the ovule.

Double Fertilization

Occurs when 1st sperm fertilizes the egg & forms a 2n zygote and the 2nd sperm fuses with the 2 female polar nuclei & forms a 3n (triploid) cell that divides to becomes the 3n endosperm (cells will be food for the embryo).

Seed Development

Zygote becomes embryo, ovule becomes seed, ovary becomes fruit Seedling germinates into full sporophyte.

Fruit Development

Unlike gymnosperms, angiosperms have an ovary that develops into a fruit for seed dispersal by wind, water, or animals.

Asexual or Vegetative Reproduction

Detached vegetative (= non‐floral or non‐reproductive) plant fragments can regrow into entire individuals that are genetically identical to the “donor” plant (i.e., clones).

Prevention of Self Fertilization

Ensures “cross‐fertilization” between different parent plants to enhance genetic variability among offspring.

Self Incompatibility

A plant can biochemically reject its own pollen.