In a tropical rain forest, there can be 42,000 species of plants in just two and a half acres of land. There are a total of 1500-2000 known species of trees.

Because of the competition between trees for light, tree trunks don't have any branches until way up high, and have flat, dense tops-so dense, it can take 10 minutes for water from a "driving tropical downpour" (Christopher Baker) to reach the ground. In fact, half to three-quarters of the total rainfall never even touches the floor! Many trees have thin bark that can soak up water as it runs down the trunk.

The canopy is continuous, and when a tree falls, new trees instantly grow up, seeing who can fill the gap quickest. The fast-growing trees have an advantage over slow-growing trees to fill gaps, but stronger slow growing trees can eventually catch up and take over.

In the Pacific Northwest, nearly all the trees are conifers-only one thousandth of the trees are broadleaf. It is about the opposite in tropical forests. Conifer and broadleaf trees are both evergreen, but are very different. Conifers are named because they have cones, and they have needles, not leaves. Broadleaves have very big leaves, for example, elephant ears and poor man's umbrella.

The advantage of conifers over broadleaves is that needles can last 15 years and are not very hard to grow, but "broad leaves" only last five months, and are huge and harder to grow. In tropical rain forests, though, broadleaf trees can get enough sunlight and nutrients to grow new leaves, and the old leaves' nutrients are soaked up again.

In tropical forests, the tree's roots are near the surface because they don't have to worry about getting enough water because of the high amount of rainfall and humidity. Also, most of the nutrients are high up. But in temperate forests, the roots go deep into the ground so that they can get more water and because more of the nutrients are down low. In old growth forests, so many epiphytic plants live and die on the branches, especially where they meet the trunk, a thick layer of soil, rich in vitamins and minerals develops. Trees have learned to use this extra source of protein and actually send roots down the trunk, way up in the canopy, to tap the nutrients of this treetop soil.

In temperate forests with heavy rainfall, such as the Olympic Peninsula, fog condenses on trees and drips to the ground like rain. One douglas fir can contain 5000 gallons of water.

In both kinds of forest, epiphytes grow on all levels of the forest, wherever there is an empty space. In tropical rain forests, this includes many orchids, mosses, bromeliads, and many more. In temperate forests, there are mostly mosses, lichens, liverworts, etc. Temperate forests have more epiphytic growth than tropical, but in both rain forests, the epiphytes can get so heavy, they can pull whole branches down.

Although there are some kinds of vines in temperate forests, such as vine maple and ivy, there are more in tropical rain forests. Vines and lianas (a type of vine) start on the floor and then climb up trees. Once they reach the canopy, they spread out to receive more light. Like epiphytes, the vines can get so heavy that the tree comes down.

An extreme example of this is the strangler fig. A seed is dropped into the canopy by bats or birds that eat the fruit, and if the seed lands somewhere there's soil, it grows up while sending a root down to the ground, soaking up whatever nutrients it can on the way down. Once the root touches the ground, the plant sends more roots down and grows higher. As it grows higher and sends more roots down, it eventually "strangles" the host tree, using up the nutrients and blocking it's light. Although this doesn't seem very moral to us, the tree provides excellent burrows for small mammals and other animals.

Below the canopy in tropical rain forests, trees that haven't reached their full height make up the understory, and the ground is covered with herbaceous plants, especially ferns. There is much more ground cover in temperate forests because more light reaches the floor. A common ground cover is salal.

The fern is the most abundant plant in tropical rain forests, and is also very common in temperate forests. They are primitive plants, living 280 to 325 million years ago. The 20,000 known kinds of ferns live all over the world, but the most diversity is found in tropical rain forests. They can be huge, tiny, ground cover, and epiphytic. Ferns average around one to two feet long, but the biggest can be 60 feet long, and the smallest can be only a half inch long. Tropically, most are epiphytes, but many more live on the forest floor. They are plentiful on the floor because not very many kinds of plants can survive with that little light.

In both rain forests, rivers and streams are very important for plants, animals, and the rain forest itself. Many plants live along riverbanks where they can get more sunlight than in the forest, and lots of animals rely on streams for water.

Orchids are one of the most diverse and amazing flowers in the world. There are an estimated 18,000 species in the world, but most live in tropical rain forests and many are in danger of becoming extinct. This is because there are so few of each kind and they are sold illegally because of their beauty. Also, many orchids rely on just one species of pollinator.

Tropically, they are mostly epiphytes, rather than ground cover, and are so diverse, there are more species of orchids in Central and South America than species of trees, herbs, and grasses in all of Europe! There are orchids in the Pacific Northwest, but with much less diversity than in tropical rain forests.

Orchids can be truly amazing. For instance, "many orchid species are marked with lines and spots like an airfield, to show the insect where to land and in which direction to taxi" (Christopher Baker). Probably the most amazing known species of orchid has a marked place for the pollinator to land near the nectaries. The nectar drugs the insect, which loses its balance and falls into a cup-shaped leaf. The only way to get out is through a tunnel, and as the drugged insect wobbles out, it hits a bar which sprays pollen on its back. By then, the pollinator is hopefully revived enough to move on to the next flower.