How thick is the bark of a redwood tree?
Sequoia sempervirens
Coast redwood reproduces both sexually by seed and asexually by sprouting of buds, layering, or lignotubers. Seed production begins at 10–15 years of age. Cones develop in the winter and mature by fall. In the early stages, the cones look like flowers, and are commonly called "flowers" by professional foresters, although this is not strictly correct. Coast redwoods produce many cones, with redwoods in new forests producing thousands per year.[18] The cones themselves hold 90–150 seeds, but viability of seed is low, typically well below 15% with one estimate of average rates being 3 to 10 percent.[34][18] The low viability may discourage seed predators, which do not want to waste time sorting chaff (empty seeds) from edible seeds. Successful germination often requires a fire or flood, reducing competition for seedlings. The winged seeds are small and light, weighing 3.3–5.0mg (200–300 seeds/g; 5,600–8,500/ounce). The wings are not effective for wide dispersal, and seeds are dispersed by wind an average of only 60–120m (200–390ft) from the parent tree. Seedlings are susceptible to fungal infection and predation by banana slugs, bush rabbits, and nematodes.[16] Most seedlings do not survive their first three years.[18] However, those that become established grow very fast, with young trees known to reach 20m (66ft) tall in 20 years.