Flowering now in the garden is the Japanese wild ginger, Asarum fudsinoi. The glossy foliage on this 15″ wide clumper makes it one of the largest of the Japanese native Asarum species. Because of its tropical roots from the Southern Ryukyu Island, Amami-Oshimi (just south of Okinawa), it’s used to flowering quite early in the year. We typically wouldn’t expect a plant from such a tropical climate to be winter hardy down to single digits F, but plants from the Ryukyu Island are evolutionarily fascinating, and far more winter hardy than their surrounding would indicate.
The Northern Ryukyu Islands are volcanic, but the Southern Ryukyu Islands, where this ginger occurs, were formed by subduction. In this case, the Philippine Sea Tectonic plate is regularly being sucked below the Eurasian plate. This makes the adjacent land unevenly rise and fall. Most of the Southen Ryukyu Islands have spent much of their lives submerged, then rising to almost 2,000′ tall, before sinking again. Most of the flora on these islands is endemic, meaning it only occurs here, hence the regions’ common name, the Asian Galapagos.
Many of these islands have only been above water level most recently for less than 500,000 years. During their Atlantian time below the surface, plants that can’t migrate well goes extinct, while those which can move, relocate to a non-submerged land mass. Temporary land bridges between the islands provide a pathway back home for flora and fauna, when they too protrude temporarily from the water. Genetic tests have shown that most of the current crop of endemic plants of the Southern Ryukyu Islands, had their genetic origin either from Mainland China or Japan. As we constantly have to remind people, native is not a place in location, but only a place in time.
I am constantly delighted by these posts! They brighten my day and broaden my knowledge. This one is especially fascinating. Back when the earth was cooling and plate tectonics only a “theory” (to others, perhaps, but not to my geology professor!) I toyed with having geology as a major and loved geomorphology. The earth has so many wonders if only one pays attention!
That was indeed fascinating. Regarding Ryukyu nomenclature, I remember entering the Naha airport terminal after landing on Okinawa and seeing a palm tree growing in a bed inside the building. The botanical label read, as I recall, Satakentia liukiuensis (I’m sure of the specific epithet) and I was immediately reminded of the oriental tendency to confuse the pronunciation of “l” and “r”.