Sequoia sempervirens

The Sequoia sempervirens (coast redwood, giant redwood, or California redwood) is the only living member of the Sequoia genus of trees in the Cupressaceae (formerly Taxodiaceae) family. It is one of the three alive species considered redwoods, with the other two being Sequoiadendron giganteum, the Giant Sequoia, and Metasequoia glyptostroboides, the Dawn Redwood. It is an evergreen, long-living, monoecious tree living from 2500 to 3500 years, and often times more. This species has the tallest trees on Earth, with the tallest tree being 379.3 feet tall (Hyperion) and 25.9 feet diameter at breast height (Lost Monarch). It is found in coastal California, and southwestern Oregon of the United States.

Description
Sequoia sempervirens have conical crowns with horizontal or slightly drooping branches. The bark of the Coast Redwood is up to 1 feet thick, soft, and fibrous with red-brown color when newly exposed, turning darker with time. The system of roots is made up of shallow, widely-spreaded linear roots. Leaves are variable, 0.59-0.98 inches long, and are usually flat on young trees, shaded in the lower crown of older trees on shoots. In the upper crown, where there is more sunlight, shoots reach 0.2-0.39 in. long. The leaves are dark green above, but on their underside are two blue-white stomatal bands below. The leafs are arranged in a spiral, but the larger shaded leaves are twisted in shape. The cones are ovular, 0.59-1.3 inches long, with 15-25 scales, each bearing 3-7 seeds 0.12-0.16 inches long, and 0.02 inches broad. These seeds are released when the scales dry out, and open. Pollen cones are ovular, 0.16-0.24 inches long. It is monoecious, with male and female pollen cones on the same individual tree.

In conifers, the genetic makeup is unusual, being a hexaploid (6n) and possibly allopolyploid (AAAABB). The mitochondrial genome is paternally inherited.

Range and ecology
Coast redwoods live in a narrow strip of land approximately 470 miles long, and 5-47 miles in width along the Pacific coast of North America, in the United States at elevations of 98-2,460 miles, and occasionally sea level up to 3,000 feet. They usually grow in the mountains, where there is more precipitation. The tallest and oldest members of this species are found in valleys and gullies, where year-round streams flow, and fog is common. The trees above the layer of fog, above 2300 feet are shorter and smaller, due to being drier, windier, and colder. In addition, Lithocarpus densiflorus, the tanoak pine, and Douglas-fir often times crowd out coast redwoods at this elevation. A small amount of redwoods grow near the ocean, due to the water being salty, sand, and wind. Condensation from fog makes up a large amount of the trees' needs for water.

The northern boundary of its range is marked by two groves on the Chetco River, 15 miles north of the California-Oregon border. The largest and tallest members of this species are found in Redwood National and State parks, in Del Norte and Humboldt counties, down to Santa Lucia Mountains of Monterey County, California.

The native area of these trees is unique, with heavy seasonal rains of up to 100 inches each year. Cool air from the coast, and fog keep the forests damp throughout the year. Though the moisture is beneficial to the trees in many ways, it also creates a soil that has less nutrients than the coast redwoods need, making them depend on the biotic community of the forest, and complete recycling of dead trees. The community of these forests include the Coast Douglas-fir, Western Hemlock, Tanoak, Pacific Madrone, and several other trees, along with several ferns, Redwood sorrel, mosses and mushrooms. The habitat of coastal redwoods proves to be home to several birds, mammals, reptiles, and amphibians.

The bark is thick and tannin-rich, which combined with foliage starting high above the ground provides good protection from fire and insect damage, the reason to the long-lived life of this tree. The oldest known coast redwood is 2,200 years old, with several others that have lived past 600 years. Because of their seemingly-timeless lifespan, and deemed the name "everlasting redwood". In Latin, sempervirens means "evergreen" or "ever lasting".

Members of this tree's genus were found almost everywhere but Antarctica, until about 5 million years ago.

Reproduction
Coast redwoods can reproduce sexually and asexually. The trees start the production of seeds from between 10-15 years old. Large seed crops occur frequently, but the viability of the seed is low, usually below 15%. The low viability may discourage predators, which won't want to waste time sorting the empty seeds and the edible ones. The winged seeds are small and very light, weighing 5,600-8,500 seeds/ounce. The wings don't help much in the movement of the seeds, only traveling 200-400 feet from the parent tree with the wind. The seedlings grow very fast, with some growing to 65 feet tall in only 20 years. Coast redwoods also reproduce asexually by layering or sprouting from the roof crown, stump, or fallen branches. If this tree falls over, it will generate a row of new trees along its trunk. This is the reason why many of this species are found in a straight line. The sprouts originate from dormant or adventitious buds at or under the surface of the bark. The dormant buds are stimulated when the main stem of the adult gets broken, or begins to die. Several sprouts can spontaneously erupt and develop from around the circumfrence of the trunk. This ring is called a "fairy ring". The sprouts can reach up to 8 feet in one growing season.

Redwoods can also reproduce using burls. These burls can sprout into new trees, when detached from the parent (this process has yet to be studied). Shoot clones are common, and are often turned into decorative hedges when found in suburbs.

This species is very resistant to flooding, and flood deposits, beacuase the roots rapidly grow into the silt deposits after the floods.

Cultivation and uses
The coast redwood is used as a valuable timber wood, with 364,000 hectares of redwood forest managed for timber production. The lumber is prized for its beauty, light-weight, and resistance to decay. Its lack of resin also makes it resistant to fire.

Because of its resistance to decay, the wood has been used for railroad ties and trestles throughout California. Many older ties have been recycled to use in gardens, steps, etc. The burls are used for making table tops, veneers, and turned goods.

The coast redwood is locally naturalized in New Zealand, and are also cultivated in Great Britain, Italy, Portugal, Hawaii, central Mexico, and the southeast United States, from Texas to Maryland.

Statistics
Trees over 200 feet are common, and many are over 300 feet.

The current tallest tree is the Hyperion, standing 379.3 feet tall. When it was discovered during the summer of 2006, Chris Atkins and Michael Taylor, where they measured it to be the tallest organism on Earth. The previous holder of this record was the Stratosphere Giant, about 370 feet tall.
 * Tallest:

There are only 41 measured trees that are over 361 feet tall.

There are 178 measured trees that are over 350 feet tall, but it is believed that hundreds of unmeasured trees over this height exist.

A tree was claimed to be 380 feet tall, but was cut down in 1912.

The theoretical maximum height of coast redwoods is between 400 and 425 feet due to gravity and friction between the water and the vessels through which it flows. The largest known coast redwood in volume is the Lost Monarch, at about 42,500 ft3. Among current trees that are alive, 6 known Giant Sequoias are larger; these are shorter, but have thicker trunks, giving the largest known member of the Sequoiadendron, General Sherman, the largest organism, at 52,510 ft3. A redwood that was cut down in 1926 was claimed to be 63,350 ft3, but this hasn't been verified.
 * Largest:

Only about 50 'albino' redwoods (mutated redwoods that can't produce chlorophyll) are known to exist, growing up to 66 feet. These trees only survive as parasites by grafting their root systems with ones of other trees.
 * Mutated members:

Largest trees
The nine largest redwoods by total volume in the trunk and stems combined as of 2009.

The order of largest and tallest can change at any given time, due to new discoveries, loss of stem or foliage, growth, and new measurements.

Tallest trees
Trees over 367.5 feet as of 2010.