Topics: Fruit, Leaf, Seed Pages: 13 (2155 words) Published: March 16, 2013

- phlya Ginkgophyta, Gnetophyta, Cycadophyta and Coniferophyta - vascular plants with true roots
- gymnosperms = “naked seeds”
- cones/strobili
- have seeds that develop on the surfaces of sporophylls instead of in ovaries like angiosperms - microsporangium produces pollen grains (sperm) and the megasporangium produces the egg - sporophyte generation is dominant

- no water needed for fertilization – pollen travels with the wind

Pine trees
- monoecious (separate male and female cones on the same plant) - have needle-shaped leaves that adapt the tree to dry conditions - produce cones – male and female
- male cones produce microsporangia (pollen sacs) that produce microspores (4) which mature into pollen grains (microgametophyte) with wings for wind dispersal - female megasporocytes within the ovule undergo meiosis early producing megaspores (4) of which three degenerate and one is functional – this one undergoes mitosis to produce the female gametophyte (megagametophyte) = egg which lies in the archegonium - Fertilization – pollen sticks to female scales to a drop of fluid which evaporates moving the pollen closer to the megasporangium and then the scales close. Pollen tube then grows down into female gametophyte and the pollen divides into 2 sperm – one fertilizes the egg to produce a zygote and the other disintegrates. - Seed coat then surrounds embryo and wings develop for dispersal

Pine Life Cycle:
(Vodopich and Moore, pg 307)

Leaves arranged in bundles (fascicles)
http://www.science.siu.edu/landplants/Coniferophyta/images/Pine.needles.JPEG Female (Ovulate) Cones

Immature female cones (winter)


Male (Staminate) cones


- woody plants that produce seeds
- resemble palms
- dioecous
- male and female cones
- insect pollinated
- Zamia genus in the US
- variation in trunk length
- life cycle similar to other gymnosperms

Zamia Male strobilus



Zamia Female Stobili




- flowering plants
- angiosperm = seeds in a fruit
- vascular seed plants
- produce reproductive structures - flowers and fruits
- differ from gymnosperms in that they produce seeds which are enclosed in ovaries as they develop



- sporophyte generation dominates the life cycle
- ovary develops into a fruit
- ovules develop into seeds
- flower produces microspores that are contained within pollen grains and the egg develops within the ovules - Fertilization (double) involves the release of pollen that sticks to the stigma and then a pollen tube grows down the style toward the ovules releasing 2 sperm - 1 of the sperm fertilizes the egg to forming a diploid zygote (2n) which will develop into a seed - the second sperm unites with the large center cell (polar nuclei) of the female gametophye resulting in a triploid (3n) cell which develops into the endosperm (surrounds the embryo and provides nutrition for the seed until it can photosynthesize on its own)

Life cycle of a typical angiosperm

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