H. capitata is found in the southern part of the Korean peninsula and in Japan. It is physically isolated from other Korean species, which explains its isolation on the family tree, as well (see the figure below). Morphologically, it is similar to the Japanese species Hosta nakaiana, but according to Suave, et al., it is genetically quite different. The tall scapes are characteristic throughout the species, but, depending on population source, there is considerable variation in leaf size. The leaves on this medium-sized plant have rippled margins. The purple flowers are tightly arranged in clusters. 

H. capitata has not been used much in hybridization, but some variations and hybrids do exist. H. 'Shirobana Kanzashi' is a white-flowered form. H. 'Nakaimo', a hybrid with H. montana, has a good flower display. It was developed in Japan and brought to the U.S. prior to 1939. H. 'Amanuma', a hybrid with H. venusta, forms a compact mound and has a good flower display. H. 'Show Piece' was also selected for its outstanding flower display. It is a hybrid with H. nakaiana.  H. 'Tatted Lace', a hybrid with the cultivar 'Ruffles', differs little from H. capitata itself. So, despite the ruffled margins of the species, breeders seemed to be more interested in the flower display, a characteristic that few hybridizers are interested in today. 

H. clausa, a medium-sized species, with the broadest geographic range of any of the Korean species, also shows the most species variation. There are four varieties in existence. H. clausa var. clausa is a triploid and is rarely found in the wild because of its genetic abnormality. The flowers of this rhizomatous spreading plant remain closed, and the plant does not form seed pods. H. clausa var. ensata has narrow lanceolate leaves. It is rarely found commercially. Another rarity is Hosta clausa var. stolonifera. Spreading by rhizomes, it never produces flowers or scapes. The variety that has been used significantly in breeding programs is H. clausa var. normalis. It is a diploid with a normal breeding program. Along with H. tsushimensis and H. yingeri, it is a major contributor to the red coloration in hosta petioles and up into the leaves. Though the oval leaves are normally a dark green, a sport with golden leaves was discovered by R. Herman and registered in 1996 as 'Golden Arrow'. H. 'Purple Lady Fingers, a hybrid with H. longissima, has a prolific display of closed purple flowers. H. 'Beauty Little Blue', a cross between H. clausa var. normalis and the cultivar 'Blue Cadet', has narrow blue foliage and spreads by rhizomes. H. 'Brooklynn's Baby Doll', a cross with H. venusta, has rippled, twisted, greenish-yellow foliage. The diminutive leaves are only three inches long.  

A characteristic of H. clausa, that Bob Solberg has attempted to take advantage of, is the purple coloration found in the petioles. He crossed 'Strawberry Banana Smoothie', a cross between 'Whiskey Sour' and a sibling, to get 'Mango Salsa', ‘Peach Salsa’, 'Lemon Ice', and 'Smiley Face'. All have red petioles, bright yellow foliage, and maintain their color in the shade. 

H. yingeri is found only on the islands of Taehuksan and Sohuksan off the southwest coast of Korea. It is found among the rocks of shady, northwest facing slopes and hillsides, often in pine forests. It was discovered in 1984 by plant collector Barry Yinger and named for him by Samuel B. Jones in 1989. The size of H. yingeri varies from 9 to 19 inches tall. Leaf size and shape are variable. Leaves are thick and succulent, with top and bottom leaf surfaces very shiny. Veins are inconspicuous on the flat leaves. A unique characteristic of the species is that the flowers are evenly spaced around the scape. The lobes of the deep lavender flowers are spread out in a spider-flower fashion. H. ‘Lily Pad’, a Bob Solberg selection with blunt leaves, is typical of those found in the wild. H. ‘Treasure Island’, another seedling selection, made by Tony Avent, has puckering between the veins. A white-margined sport of H. yingeri showed up in the tissue-culture lab of Mark Zilis, and he named it ‘Gentle Spirit’.

H. laevigata is found on the same islands as H. yingeri and is closely related to it, but has lighter green lanceolate leaves with a wavy margin. It also claims the spider flower characteristic, but they are larger than those of H. yingeri. Unfortunately, it is difficult to hybridize because it does not readily form seed pods. George Schmid crossed the pollen of H. laevigata onto H. longipes f. sparsa to get a seedling, which he then crossed with H. yingeri. The result is the cultivar 'Gosan Leather Strap'. A few sports also exist, most notably 'Ray of Hope'. This heavily streaked plant sported in the tissue culture lab of Mark Zilis, resulting in the selection 'Roller Coaster Ride'.  

H. venusta is only found on Cheju Island off the southern coast of Korea. The phenotype imported and available in the trade is a miniature form, although much larger forms of H. venusta exist in the wild, but are not available. Maximum height on this natural dwarf is six inches. Because of its diminutive size, it has been much used in hybridizing. Though much variation exists in the wild, some even with a piecrust margin on the leaves, up until 1990 only one type existed in the U.S. The cultivars 'Minuta', 'Minima', 'Rock Princess', 'Thumbnail', 'Suzuki Thumbnail', 'Tiny Tears', and 'Akarana' are all selfed forms of H. venusta that are essentially look-alikes to that original introduction. 

H. 'Gemstone' H. 'Riviera Sunset' H. 'Lakeside Neat Petite' Three examples of hybrids where H. venusta was the pod parent are 'Gemstone', 'Lakeside Neat Petite', and 'Masquerade'. H. 'Gemstone' is a cross with 'Dorset Blue' and resulted in a low mound of blue-green foliage, essentially inheriting the best qualities of both parents. H. 'Lakeside Neat Petite', a cross between H. venusta and 'Blue Cadet', develops into an eleven inch mound of heart-shaped green foliage. It has a notable display of bright purple flowers formed on scapes just above the foliage. H. 'Masquerade' is a well-known cross between H. venusta and a sport of H. sieboldii. It forms an attractive six inch mound of white-centered, green-margined foliage. Unfortunately, it has a tendency to sport green-leaved shoots. A fine stable sport of it, though, is 'Little White Lines'. Discovered by Mark Zilis in his lab, it forms a small mound of white-margined foliage.  Many crosses have also been made using H. venusta as the pollen parent.  Bob Solberg crossed H. venusta with 'Shining Tot' and got 'Cody' as a result, a six inch mound of dark green leaves with good substance. Tony Avent used multiple crosses which included H. venusta. Among his introductions are 'Hush Puppie' and 'Appetizer'. H. 'Hush Puppie' is a small mound of green-centered, white-margined foliage. H. 'Appetizer' is a small mound of green-centered, yellow-margined foliage.   Korean species map H. 'Imp'

Mark Zilis wondered what would happen if he crossed the largest hosta known at that time ('Sum and Substance') with the smallest. A wide variety of progeny resulted, including 'Leather Sheen' and 'Little Razor'. H. 'Leather Sheen' forms a medium-sized mound of shiny, dark green foliage with a rapid growth rate. H. 'Little Razor' is a small plant with golden foliage. Three other cultivars from that same cross are 'Golden Decade', 'New Wave', and 'Courtesy'.  Don Dean went one step further, crossing 'Leather Sheen' with 'Beatrice'. The result, 'Riviera Sunset', is ten inches tall and has an orangey-golden edge surrounding a green center.  Hans Hansen made an interesting complex cross where H. venusta was in both the pod and pollen parents. He first crossed 'Yellow Splash' with H. tibae and then crossed this plant with H. venusta. The resulting seedling was then used as the pod parent.  The pollen parent was a seedling, which came from a cross between H. venusta and 'Shining Tot'. The end result was a plant the size of H. venusta he named 'Imp', which has white margins on shiny, slightly wavy leaves.

Taxonomically similar to H. venusta, according to Chung, et al., is H. minor.  It is found in the southern and eastern regions of Korea and is distinguished by the distinctive ridges along the scape. Similar to H. venusta, it reaches a height of just eight inches. The problem with using this species in breeding programs is that most of the plants listed as H. minor in the US are not actually H. minor. It is not only confused with H. venusta, but with H. nakaiana and H. sieboldii as well. A rare hybrid of H. minor is called 'Mrs. Minky'. It is a cross with 'Piedmont Gold' and forms a small mound of chartreuse foliage with rippled margins. No other hybrids are known at this time.  H. tsushimensis is only found on Tsushima Island, which is in the Korean Strait between the Korean peninsula and Kyushu Island in Japan. Though it is typically about 12 inches tall, other characteristics are quite variable. The leaf margins may be smooth or wavy. Inflorescences are branched in some populations, not branched in others. Moreover, it may be found on moist or dry sites. Though normally found with light purple flowers, a white-flowered form known as 'Shirobana Tsushima', exists too. A rare yellow-flowered form, obtained by Mark Zilis from friends in Japan, will soon be on the market.  H. 'Cody'   H. 'Leather Sheen'

Taxonomically similar to H. tsushimensis is H. jonesii. M. G. Chung discovered it in 1989 and named it after another plant explorer, Sam Jones. It is found on several islands off the southwest coast of Korea and differs from H. tsushimensis by having a creeping rhizome and reddish-purple scapes. The average size of this species is about 13 inches tall. George Schmid states that it is a worthy plant, but, as of now, no cultivars or selections exist. Though you may be inclined to add H. jonesii to your breeding program, be forewarned that most plants sold as this species in the U.S. are not correctly identified. 

Knowing the characteristics of hosta species and isolating those characteristics in breeding programs may result in unique plants for the hosta market. Bob Solberg states that he never intended to just use the Korean species for producing red in the petioles, but the similarity of the genes of the Korean species may have helped push the red color further into the leaves. Crossing a plant with red in the flowers (i.e., H. tsushimensis) with one that has red in the petioles (i.e., H. clausa var. normalis) may result in further concentration of the red pigments.  

In addition to the red pigment, the Korean hostas have many desirable features. It is time more hosta hybridizers took a closer look at them for their breeding programs.
 

References: 

1.       Chung, M.G., Jones, S.B., Hamrick, J.L., and Chung, H.G.  "Morphometric and Isozyme Analysis of the Genus Hosta (Liliaceae) in Korea."  Plant Species Biology, 6 : 55-69.  1991. 

2.      Schmid, W. George. The Genus Hosta - Giboshi Zoku. Timber Press, Portland, OR. Batsford Ltd. London. P. 64-65, 316; 1991. 

3.      Suave, R.J., Zhou, S., Yu, Y., and Schmid, W.G.  "Random Amplified Polymorphic DNA Analysis in the Genus Hosta.  HortScience.  40(5): 1243-1245.  2005. 

4.      Schmid, W. George. “The Ridged Hostas of Korea”. The British Hosta and Hemerocallis Bulletin. P. 38-45; 1997.