Angiosperm.html: 30_13mMonocotsEudicots-L.jpg
Monocot characteristics:

• One cotyledon
• Parallel leaf veins
• Stem vascular tissue scattered
• Floral organs usually in multiples of three

• Two cotyledons
• Netlike leaf veins
• Stem vascular tissue arranged in ring.
• Floral organs usually in multiples of four or five

Angiosperm_cycle.html: 30_10AngiospermLifeCycle.jpg
The life cycle of an angiosperm.

1. Anthers contain microsporangia; microsporocytes divide by meiosis to produce microspores.
2. Microspores form male gametophytes (pollen grains) which produce 2 sperm and a pollen tube.
3. Ovaries contain megasporangia; a megasporocyte divides by meiosis to yield 4 megaspores; one forms a female gametophyte (embryo sac).
4. 2 sperm nuclei reach an ovule and double fertilization occurs.
5. One sperm fertilizes the egg to form a zygote, the other fuses with 2 nuclei of the cetral cell to form a triploid endosperm.
6. The diploid zygote develops into an embryo within a seed.
7. A seed can germinate into a sporophyte.

Coniferophyta.html: 30_04aGymnospermConiferophyta.jpg
Coniferophyta. Pseudotsuga menziesii (Douglas fir) produces more timber than any other American forest species. Pinus longaeva (Bristlecone pine) can reach ages of more than 4,600 years. This Sequoia giganteum (Giant Sequoia) weighs about 2,500 metric tons (about 24 blue whales, or 40,000 people). The "berries" of Juniperus communis (Common juniper) are ovule-producing cones consisting of fleshy sporophylls.

Coniferophyta2.html: 30_04aGymnospermConiferophyta2.jpg
Coniferophyta. Pinus longaeva (Bristlecone pine) lives in the White Mountains of California, and can reach ages of more than 4,600 years. This Sequoia giganteum (Giant Sequoia) weighs about 2,500 metric tons (about 24 blue whales, or 40,000 people). The related Sequoia sempervirens (Coast Redwood) can grow to more than 110 meters, 1/4 the height of the Sears tower.

Cycadophyta.html: 30_04aGymnospermCycadophyta.jpg
Phylum Cycadophyta. Cycads have large cones and palmlike leaves and thrived during the Mesozoic era - "Age of Cycads" ("Age of Dinosaurs").

Gingkophyta.html: 30_04aGymnospermGingkophyta.jpg
Gingko biloba is the only extant species of phylum Gingkophyta. Landscapers usually plant only pollen-producing male trees because the fleshy seeds smell rancid as they decay.

Gnetophyta.html: 30_04aGymnospermGnetophyta.jpg
Gnetophyta. Gnetophytes live in tropical and desert environments.

• Welwitschia can absorb water through structures on its large leaves.
• Gnetum species are tropical trees or vines.
• Ephedra (Mormon Tea or Ma Huang) is a desert shrub.
  Ephedrine extracts have been used as a diet pill, but carries cardiovascular risks that may have led to deaths including Minnesota Viking Korey Stringer (2001) and Baltimore Orioles pitcher Steve Bechler (2003).

Gymnosperm.html: 30_UN593PlantPhylogeny.jpg

Gymnosperm_cycle.html: 30_06PineLifeCycle.jpg
Life cycle of a conifer (a gymnosperm).

1. Sporophytes bear pollen and ovulate cones.
2. Pollen cones contain microsporangia with microsporocytes.
3. Ovulate cones contain ovules, each with one megasporangium and a megasporocyte.
4. Microsporocytes undergo meiosis to produce male gametophytes (pollen grains).
5. The megasporocyte undergoes meiosis to produce a megaspore.
6. The megaspore develops into a female gametophyte containing eggs.
7. The pollen grain germinates a sperm cell which travels down the pollen tube to fertilize an egg to produce a zygote.
8. The ovule becomes a seed: an embryo, food supply, and seed coat.

dicot.html: 30_dicot.jpg

dispersal.html: 30_09FruitDispersal.jpg
Fruit adaptations that enhance seed dispersal. Wings enable maple fruits to be carried by the wind. Seeds within berries and other fruits are dispersed in animal feces. The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals.

flower.html: 30_07FlowerStructure_L.jpg
The structure of a flower. Sepals enclose the flower, petals may be brightly colored to attract pollinators. Stamens produce pollen, and carpels contain ovaries. An ovary caontains several ovules which develop into seeds after fertilization. The stamens collectively are called "androecium", while the carpels are called "gynoecium". A complete flower has all four basic floral organs. A perfect flower contains both male and female structures. _Vid_Campbell7e/FlowerTimeLapse-V.swf

fruit.html: 30_08Fruit.jpg
The wall of the fertilized ovary thickens into layers of pericarp surrounding a fruit. Fleshy fruits, such as tomato (2 soft layers), grapefruit (firm outer layer, soft inner layer), and nectarine (soft outer, firm inner pit), attract animals which eat the fruit and aid in dispersal of the indigestible seeds. Dry fruits, such as milkweed and hazelnut, are often adapted for dispersal by wind or water, or by animal carriers.

gameto.html: 30_02GametoSporophyteSeedless.jpg
Bryophytes have life cycles dominated by gametophytes. Seedless vascular plants have sporophyte-dominated life cycles, with small, free-living gametophytes. Gametophyte reduction continued further in seed plants, becoming microscopic and dependent upon the sporophyte for nutrition and protection.

gametophyte.html: 30_02GametoSporophyteSeeded.jpg
Seed plants are heterosporous. Different spores produce reduced male and female gametophytes, which in turn produce gametes. The tiny gametophytes are dependent upon the sporophyte for nutrition and protection.

megaspore.html: 30_03OvuleToSeedA.jpg
Unfertilized ovule.
In the ovule of a pine (a gymnosperm), a fleshy megasporangium is surrounded by a protective integument. (Angiosperms have two integuments.)

microspore.html: 30_06PineLifeCycle_1-L.jpg
Male gametophytes.
Pollen cones contain microsporangia where microsporocytes undergo meiosis to produce microspores, which develop into male gametophytes (pollen grains).

monocot.html: 30_monocot.jpg

ovule.html: 30_03OvuleToSeedB.jpg
Fertilized ovule.
A megaspore develops into a multicellular female gametophyte. A pollen grain (male gametophyte) enters through the micropyle, and develops a pollen tube in which the sperm can travel.

pollination.html: 30_13FlowerPollinator.jpg

A flower pollinated by honeybees. This honeybee is harvesting pollen and nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping mechanism that arches the stamens over the bee and dusts it with pollen, some of which will rub off onto the stigma of the next flower the bee visits. _Vid_Campbell7e/BeePollinating-V.swf		A flower pollinated by hummingbirds. The long, thin beak and tongue of this rufous hummingbird enable the animal to probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive.		A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate.

seed.html: 30_03OvuleToSeedC.jpg
Gymnosperm seed. After fertilization, the ovule develops into a seed A seed consists of an embryo along with its food supply packaged in a protective seed coat derived from the integument.

seed_plants.html: 30_01SeedPlantsMeds.jpg
A Sampling of Medicines Derived from Seed Plants. Seed plants provide many products including food, wood, and many medicines.