Sharing the Planet

From the study of fossilized cones, it’s known that redwood-like true conifer trees existed at least 240 million years ago, before the earliest known dinosaurs. A mere 50 million years later, trees of the redwood family and dinosaurs co-existed together. These early redwoods once grew across a wetter, warmer Northern Hemisphere. Over time, and as the climate changed, many redwood species became extinct, with only three species remaining today: giant sequoia (Sequoiadendron giganteum), coast redwood (Sequoia sempervirens), and dawn redwood (Metasequoia glyptostroboides), the smallest of the three species. Visitors to the Garden can see these majestic trees, including the most unique of the three: dawn redwood.

Dawn redwood is deciduous–its needles change color and drop in the fall, as seen in the circle of trees located in the Asian area at the Garden.

Unlike coast redwood and giant sequoia, which are evergreen, the dawn redwood is deciduous–its needles change to a rust-red color and drop in the fall. Deciduous conifers aren’t very common today, but quite a few evolved in warmer epochs. The artic circle then was clement enough to support dense, towering forests, but still experienced months of very little sunlight. Dawn redwood is one of the trees that adapted to the long, dark, but not so cold, winters.

Dawn redwoods are distinguished by the flowing, overlapping trunk structure at the base of the tree.

Dawn redwood has a fascinating history and connection with UC Berkeley. What was thought to be an extinct genus, it was described by scientists in 1941 from fossils found in Japan. However, it would be revealed that earlier, the discovery of North American fossil Metasequoia also happened at the University of California, Berkeley. James Ashley, an undergraduate student in Professor Ralph Chaney’s 1939 paleobotany class, delivered a term paper describing conifer fossils found in Nevada from the Eocene epoch. Ashley noted in his paper that there were two different leaf arrangements, opposite and alternate, and called them Taxodium 1 and 2, thinking they were in the same genus as bald cypress (Taxodium distichum). At the time, Professor Chaney did not recognize the significance of Ashley’s find, later realizing after the 1941 publication that the many fossils he had previously identified throughout western North America as coast redwood (Sequoia sempervirens) or bald cypress (Taxodium distichum), were actually dawn redwood (Metasequoia glyptostroboides).

Redwood trees are gymnosperms, plants that reproduce by bearing seed-filled cones. Redwood cones and seeds are surprisingly small. (Dawn redwood leaves and cones pictured.) The tallest tree living on the planet–the coast redwood tree–produces the smallest cones in the redwood group!

A Collection Expedition to China
In 1944 it was discovered that dawn redwoods were not extinct when a grove of approximately one thousand trees was found in a remote region in China. Professor Chaney visited China with a team in 1948 to collect seeds and seedlings of dawn redwood. These were widely distributed, including specimens to the Garden. Planted in 1949, these trees were some of the first to grow in North America in over 20 million years! Considered an endangered species, the Garden is preserving and protecting dawn redwood trees for future generations. Visit the Garden and experience the wonder and awe of these magnificent trees!