Scientific Name: Gunnera tinctoria
Common Names: Chilean rhubarb, giant rhubarb, dinosaur food
Plant Type: Clump-forming, herbaceous perennial. Fast-growing, huge!
Environment: Partial sun to partial shade, organically rich, needs wet or consistently moist soil.
Bloom: In late spring very small, rusty-red flowers emerge, clustered on robust, 1.5 foot-long corn cob-like spikes.
Uses: Dramatic foliage in very wet areas. Used as a water garden accent. Needs lots of space!
Mesoamerican Cloud Forest 14A;
Camellia Garden: 58A, 58F;
Ancient Plant Garden 67A, 68A, 68B, 68E
One of the most distinctive, largest-leaved specimens in our collection is Gunnera tinctoria, commonly called Chilean rhubarb. With prickly leaves that can reach 6 feet in diameter and an overall plant that is equally as tall, Gunnera tinctoria is a force to be reckoned with. A native to both Chile and Argentina, this eye-catching monster appears both tropical and prehistoric... right out of a deep jungle with other giants, such Apatosaurus or Tyrannosaurus.
Although Gunnera tinctoria does not fit the "tropical" moniker, many other of the over 70 accepted species of Gunnera do. Likewise, this genus is definitely prehistoric, with pollen grain fossils found in strata dating back at least 95 million years. By comparison, unearthed Apatosaurus fossils date back as far as 152 million years, and Tyrannosaurus fossils date back "only" as far as 68 million years. Was Chilean rhubarb food for herbivorous dinosaurs? In its native region today, petioles (commonly called leaf stems) and young shoots, collectively called nalcas by locals, are peeled and eaten raw or as a cooked vegetable.
Different species of Gunnera can be found living around the globe today, from Mexico to Latin America, Hawaii, islands in the South Pacific, Southeast Australia, New Zealand, Africa, and Madagascar. In spite of this apparent broad distribution, pollen fossils from around the world indicate Gunnerapopulations were much more expansive in the distant past, with pollen specimens found in Russia, India, Eastern Europe, and North America, among other locations. Researchers propose the decrease in distribution may be related to the decrease in rainfall and increase in temperature fluctuations experienced by these earlier-inhabited regions. Today, all Gunnera species are isolated to environments with heavy rainfall.
With an introduction to ornamental horticulture, Chilean rhubarb has become invasive in environments where humidity and water are readily available. The United Kingdom, the Azores Islands of Portugal, New Zealand, and the coastal Bay Area of California have all become satellite homes to this strong competitor. Both Point Reyes National Seashore and Tomales Bay State Park host naturalized colonies of Gunnera tinctoria. With this species’ affinity for our maritime climate and small seed that is likely distributed by wind and water (and perhaps on the feet of birds), this is a specimen that should be cultivated with caution in our region. At the San Francisco Botanical Garden, flower stalks responsible for producing seed are pruned and composted annually prior to seed maturation.
IN BLOOM CONTRIBUTORS: Text by Corey Barnes and Profile by Mona Bourell. Photos by Joanne Taylor and David Kruse-Pickler.