What are Adaptations?
Background information for the teacher
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The special characteristics that enable plants and animals to be successful in a particular environment are called adaptations.

The ability of a cactus to store water or a passionflower vine to climb towards the sun are adaptations to environmental conditions-the dry desert, a crowded jungle floor. Adaptations are all strategies to meet the basic needs of a plant species.

To begin exploring adaptations, recall plants' basic needs:

• Sunlight to manufacture food through photosynthesis, typically undertaken in the leaves and stems.
• Water usually taken up from the soil through their roots.
• Air is necessary for the photosynthesis process as the plant takes in carbon dioxide and releases oxygen.
• Nutrients are typically absorbed from the soil through the root system.

The three galleries we'll be visiting on the Adaptations Tour represent three tropical environments, each with its own set of challenges for plants. The Lowland Tropics gallery is filled with tropical plants from the hot, steamy rainforest and other sea level areas of the tropics. The Highland Tropics gallery contains plants growing in the cool, higher elevations. And, the Aquatic Plant gallery returns to sea level with a collection of plants found in the rivers, lakes and bogs of the world's tropics.

How do these environments affect plant populations?

The heat and moisture of the lowlands are ideal for plant growth and it's a very lush, dense place. In the Lowland Tropics gallery, you'll encounter:

• Very tall plants, all competing with one another to reach the sunlight.
• Plants with very big leaves to trap sunlight for photosynthesis.
• Vines crawling up tree trunks to reach sunlight.
• Leaves with a "drip tip" at the end that gently channels the water off the leaf and onto its roots. In the warm, steamy tropics, plants need to shed water to avoid growth of molds, moss, algae and lichens on their leaves.
• A multitude of other leaf shapes designed to drain water, and/or withstand winds-the palm leaf, philodendron leaf and banana leaf with its ability to tear in the wind and still survive.
• Plants with above- ground stilt roots that provide support for plants growing in the shallow, wet soils of the tropics.

In the Highland Tropics gallery where it's much cooler, windy and just as wet, you'll encounter:

• Epiphytes, plants growing on plants where they're closer to the sun.
• Bromeliads, an epiphyte, whose leaves form a tight cup to hold water.
• Orchids, another epiphyte, with aerial roots designed to absorb moisture from the air and hold water like a sponge.
• Orchids with water-storing (succulent) stems and leaves. (Plants growing high in the air, don't have access to the moist soil below. They have many of the same adaptations as plants from drier environments.)
• Relatively small leaves found on many of the plants from the mountainous regions of the tropics lose less water during transpiration (the release of the byproducts of photosynthesis, oxygen and water).

And finally, in the Aquatic Plants gallery with its collection of plants from the rivers, lakes and bogs of the world's tropics, you'll encounter:

The giant amazon lily with many adaptations including:

• Razor sharp spines to protect it from predators.
• A super strong structure allowing the leaves to grow to six feet wide.
• Waxy surface on the leaves allowing water to easily run off.
• Turned up rim on the leaf is thought to serve as a bumper preventing leaves from overlapping one another, blocking sunlight.
• The slit in the rim allowing water to drain off.
• Hollow stems allowing air to reach the roots.

Carnivorous plants

• These plants are native to nutrient poor bog and soils. To gain needed minerals, the plants developed a series of devices to trap insects, and on occasion small mammals.
• In the pitcher plant, insects are lured into the pitcher by the scent of nectar, once inside the waxy tube, the insect slides into the base of the pitcher where a pool of enzymes waits to decompose the victim.

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