Plant Science: An Introduction to Botany

Although almost every child knows the difference between an elephant and a giraffe, few people of any age can name the plants they see out their window every single day. Solve this "plant blindness" by learning about the fascinating lifeforms to whom we owe so much: oxygen, food, medicine, materials - but also fascination and joy.

Although our biology is significantly different than that of plants, scientists are discovering more and more similarities. We share quite a bit of DNA, thrive in moderate temperatures, have a circadian rhythm of rest and activity, require water for life, and can sense our environment and respond. Some scientists suggest that plants might even have developed a type of "hearing."

More than 425 million years ago, a group of plants called bryophytes developed two special adaptations that allowed them to inhabit dry land. Why are these early plants still so important today, both environmentally and commercially? And how does one of these most ancient species engineer its own habitat to the exclusion of more modern competitors?

Botanists still struggle to unravel the full evolutionary history of ferns, hardy plants of staggering reproductive and colonization power. With billions of lightweight spores produced by each individual and the vasculature to transport nutrients throughout the plant, ferns are found in low-light and bright-light environments from the arctic regions to the tropics.

Photosynthesis might be the "star," but what takes place under the soil is just as imperative for plant survival. In fact, the root is so important that it's the first evidence of germination in the seed. Learn how roots physically support the plant, absorb water and minerals, and store carbohydrates, almost always relying on symbiosis with bacteria and fungi.

Learn how the pressure flow hypothesis models the movement of sugars through the plant's phloem and xylem, and what plant structures determine whether the organism will grow in height, girth, or both. And while the stem functions to support the plant's branches and leaves, in some plants the stem is also the site of photosynthesis.

Plants "know" when to shed their leaves or grow new ones via the same mechanism that causes the many developmental changes in our own bodies: hormones. Learn about the hormones that affect leaf growth and abscission - and the role played by Charles Darwin in their discovery.

Green plants generate their mass - whether the mass of the smallest blade of grass or the tallest tree on Earth - by synthesizing food from carbon dioxide and water via the energy from sunlight with the help of appropriate enzymes. See how the fascinating details of photosynthesis separate the plants from the animals.

How do plants "choose" the best time to flower? Do they sense the daylight hours becoming longer in the springtime? Or do they sense the nights becoming shorter? Learn which pigments interact with sunlight to serve as chemical clocks for flowering plants and what roles are played by messenger RNA and temperature - including their part in climate change.

While spores have continued to provide effective reproduction through the millennia, evolution has led to several successful alternatives. In a little package of embryonic roots, stems, leaves, and nourishment, a seed offers the ability to lie dormant until conditions are right for the highest chance of survival. Learn about the unique properties of the cycads, gingkos, and gnetophytes.

Meet the conifers, well-adapted to snow, wind, fire, and low-nutrient soils. Learn how the unique properties of conifers allow them to claim the largest forest on Earth, the oldest living tree, and the tallest plant - with a growth rate of up to six feet per year. Conifers are also the source of one of the most prescribed cancer drugs on the market.

Flowering plants arrived relatively late in geological time. But once here, they evolved quickly and often displaced many other types of plants. In fact, in terms of species, flowering plants are the dominant plant form on Earth today with more than 300,000 types. Learn how their unique reproductive mechanisms led to this explosion of speciation in such a relatively short time.

Which came first - the pollen or the pollinator? Learn about the special evolutionary relationship between specific flowers and the insects, birds, and mammals that play a necessary role in plant reproduction. The flowers' morphology, color, and quality and quantity of scent are all related to "their" animals' body shape, sense organs, and more in this never-ending co-evolutionary tango.

If you think you know the difference between a fruit, a nut, and a fungus - think again. Learn the real difference between nuts, fruits, and seeds, and why so many foods we eat carry misleading common names. As for those beautiful and tasty fungi, you might be surprised to find out they have more in common with you than with plants!

The evolution of the seed was a major advantage for land plants. But unlike gymnosperms, the flowering plants produce a fruit around that seed, aiding in germination, dispersal, or both. Learn about the many fascinating ways seeds are dispersed - from animal deposition, to wind and water dispersal, to seed explosion.

Learn how seagrasses, mangroves, and other aquatic plants evolved to tolerate low light levels, anaerobic and nutrient-poor sediments, and the difficulty of getting CO2 into submerged leaves and stems. They also benefit surrounding ecosystems by keeping excess nutrients from the ocean, trapping river and ocean-floor sediments, and providing habitat and protection for animals.

From the shade-adapted plants living on the rainforest floor to the epiphytes in the top of the canopy - and the myriad plants and animals in between - tropical regions are the most diverse ecosystems on land. Learn about the unique ways in which bromeliads, orchids, and lianas, among others, "make their living" near the top of this diverse ecosystem.

The grassland ecosystem - steppe, prairie, savanna, and rangeland - is found on every continent except Antarctica. Estimated to cover almost one-third of the land area of the planet, grasses developed unusual adaptations related to the location of their growth tissue and their specific mechanism of photosynthesis. Learn how grasses play a major role in the development of human society.

Not an herb and not a tree, shrubs' in-between status carries ecological advantages allowing them to grow almost everywhere. Many are fire-adapted, some communicate through volatile organic compounds released by the leaves, and others exude chemicals from their roots that prevent other plants from growing nearby.

Deserts contain the largest variety of plant shapes on earth. Along with these multiple morphological adaptations to a lack of water, desert plants have also developed an alternative pathway to photosynthesis, opening their stomata at night, storing the CO2, and using it during the day with closed stomata, thereby avoiding daytime water loss.

Trees are a wonderful example of convergent evolution. While many trees are evergreen and others are drought deciduous, temperate trees lose their leaves in the winter because the trade-off of keeping a leaf from freezing doesn't offset the photosynthetic gain. But even after the leaves turn color and drop, the tree roots of some trees can still forage through the soil for nutrients.

Alpine plants face a short growing season, freezing nights almost year-round, extraordinarily high light levels on cloudless days, fierce wind, and severe lack of moisture. Learn how the unique rosette and cushion morphologies allow alpine plants to thrive in this environment - as well as provide a sheltered place for other plants to germinate - and how heliotropism aids in pollination.

About 600 species of plants eat animals. Others are outfitted with poison-injecting hairs you do not want to trigger. And then there are the "everyday" poison oak, ivy, and sumac. But the real plants to fear? The invasive species that have taken over millions of acres, to the detriment of species diversity, animal habitat, and entire economic systems.

Genetically modified organisms are in the news almost every day. They are lauded for solving numerous agricultural problems and reviled for their perceived "Frankenstein" nature. But what is the truth about GMOs? Learn what scientists have accomplished, what might be possible in the future, and the very real dilemmas we face in this brave new world of plant science.