Diapensia on Cheju Island, South Korea....... and Musings on Origins

Well north of Okinawa and 270 km south of the Democratic Republic of Korea (South Korea) is the roughly oval and largely volcanic island of Cheju (33,30 N,). It is best known as a resort island, a big producer of mandarin oranges, and having the longest lava caves in the world. It is also the only place to find Diapensia lapponica subspecies obovata in Korea. This plant is an evergreen, woody, white-flowered cushion-plant with leaves changing from a burgundy-wine colour in the cold periods to an olive green in summer. The plant has dispersed around the northen arctic-subarctic world and colonized some temperate alpine areas in New England, Japan and Scotland. Water bodies pose a small barrier. Diapensia seed is carried on the wet feet of birds and/or blows across sea ice. It even reached Iceland.

Some Background Research
I studied Diapensia for several years in Newfoundland and most of what I learned/discovered is collected in the bibliography of my Atlas of Labrador Plants Vols. 1 & 2 (Memorial University, Queen Elizabeth Library, Newfoundland). Internet correspondent Prof. Ulf Molau (Gothenburg U.) has extended some of this work in northern Sweden by measuring plant clump diameter and thus estimating age of individals. Some large plants are more than 700 years old. 20% of the northern Swedish study population has been killed off by global warming (discussed, 2002, Rural Delivery magazine, Nova Scotia). Newfoundland and Korean populations are not being monitored for die-off.

Mount Halla and Destructive Hikers

High on top of Mount Halla (1950 meters) at the center of Cheju Island is the extinct volcanic cone, last active about 1007 AD, around 200 years before the Mongol invasion (1230 AD). As I climbed I felt more and more at home surrounded by twisted spruce, fir and birch. I even saw a minature Gentian growing in wet gravel. It had a single blue bloom like Newfoundland's G. nesophila. The subarctic and temperate alpine regions are really very much alike. Near the crater cone is where Diapensia grows in the cool air, often surrounded by fog. You may think I saw the plant with my own two eyes but I did not, though I have visited Cheju three times since 1997. The last few kilometers on the trail to the volcanic cone are closed to the public, and guarded, and have been since I arrived in 1996. Disappointing. Korean hikers typically stray off the paths crushing the plants and soil and this has produced severe erosion. I have even witnessed hikers breaking off walking sticks along the way. Most mountain vegetation can sustain small impacts but Korea's 45 millions put a lot of strain on the trails. The park authorities have placed soil-filled, beige, plastic, mesh bags over the eroded areas. These are gradually being colonized, especially by rushes and sedges.

Some History of Cheju Island

Cheju was not an island in the last glacial period (10,000 BP). The sea level was about about 100-125 meters lower and Cheju was connected to China and S. Korea, perhaps Japan. At that time the climate was colder and the vegetation and animal life had a more northern character. Diapensia may have dispersed to Cheju in these colder periods.?The original people inhabited Billemot Cave as early as 40,000 B.P. in the mid-paleolithic period and Eurasian Brown Bear also lived in this same cave (now extirpated or killed out). Sitka Deer, Boar and a small wild cat species have been killed out in recent times, as a result of human pressures. The original people of Cheju were the Tamna or Tamla and I believe they spoke a different language from the mainland Koreans. Remnants of this language have survived and is now incorrectly referred to as a dialect. The original matrilineal Tamna people have been culturally and genetically swamped by patrilineal Koreans since contact with the Baekjay Kingdom period (18 BC-600 AD), though this is not acknowledged or discussed here.

Diapensia in the Chinese Himalayas..home origins

Years ago, 1980-81, while at the U. of Ottawa, I borrowed numerous Diapensia species from Edinburgh's Royal Botanic Gardens. This great garden and herbarium has been a center of study of alpine plants for decades, with special expeditions into the Tibetian, Chinese and Nepalese Himalayas. Explorers collected some new Diapensia species and viable seed. After examining these plants I concluded informally that D. lapponica was most similar, in fact, almost identical to white-flowered north Chinese specimens of D. purpurea! In other words, D. purpurea is almost identical to D. lapponica other than the fact that its flowers are violet-purple.

Here then in northern China was the likely home of D. lapponica, and from here it struck north, both east and west into the circumpolar arctic during one of the earth's many glacial occillations.

The purple flower colour is a minor trait and the two species may best be lumped. The name Diapensia lapponica has priority and D. purpurea would be discarded, as Carl Von Linnaeus described it very early after his Lapland plant collecting in 1731. Mainland Chinese botanists (and the staff at the Edinburgh Gardens) are in the best position to answer this question. An alternative view/hypothesis would be that Diapensia lapponica actually grows in north China but has been mislabeled as D. purpurea var. alba. This needs to be sorted out. Any new students interested? There would be some hurdles. Diapensia is notoriously difficult to cultivate at low altitude/latitude, but Edinburgh has succeeded.

Evolution of Diapensia

Diapensia is adapted to a cool, humid, arctic-alpine environment. Diapensia's early ancestors would have had larger leaves and more flowers on the stalk. They probably looked very like the bigger evergreen members of the family in the distant past, species such as Shortia and Galax. These resemble the Pyrolas. Today Diapensia resembles Pyxidanthera most closely. This trailing, evergreen, small-leaf genus grows only in the New Jersey Pine Barrens, and is threatened by habitat loss. Diapensia may have been adapted originally to life under an open forest canopy. Many alpine species are believe to have started this way and were literally lifted to high altitude over geological millenia while evolving more compact forms. Someone else said it before: these alpine plants are truly older than the hills. In their history and protoplasm they hold many untold stories.

This article was first published in the wildflower magazine of Newfoundland and Labrador: Sarracenia

Copyright 2006 Robin Day