In the last issue of the Hosta eNewsletter, I began a series on the Japanese hostas, talking about Hosta alismifolia. Continuing the series, this article will discuss H. nakaiana (Kanzashi Giboshi,) the Ornamental Hairpin Hosta.
Populations of Hosta nakaiana are found in various sites throughout Japan. Speculation is that it evolved from displaced specimens of H. capitata, but it may also have developed from interspecific crosses with other Japanese hostas. At one time it was included with the species H. capitata, but the two differ in several significant features. The underside leaf veins of H. capitata are papillose (covered with tiny protruding cells), whereas those of H. nakaiana are smooth. H. capitata has scapes that are 22 to 32 inches long, whereas those of H. nakaiana are 15 to 23 inches. H. nakaiana has 10 to 22 flowers per scape, H. capitata only 5 to 10. In addition, the two are quite different genetically.
Hosta nakaiana forms a dense mound, up to 12 inches tall and 32 inches wide, though usually smaller. The leaf is somewhat heart-shaped, medium to dark green above and lighter green below. The underside of the leaf is shiny. Flowers are pale purple-violet with white markings. Flower scapes are exceedingly abundant. Because of the good fertility that this species exhibits, many hybrids have been produced. During the 1970’s it was one of the favorite species of hybridizers, especially Eunice Fisher and Robert Savory.
Among the cultivars derived from H. nakaiana is ‘Golden Tiara,’ a classic hosta and matriarch of the “Tiara” family. No less than 34 hosta cultivars are in the hosta database with ‘Tiara’ listed as part of its origin, and 29 have ‘Tiara’ as part of its name (though at least one of these, ‘Royal Tiara,’ has a different derivation.) Among the most popular are ‘Diamond Tiara’ and ‘Grand Tiara,’ as well as ‘Jade Scepter,’ ‘Emerald Scepter,’ and ‘Golden Scepter’. In addition ‘Teaspoon’, one of my favorites, is a cross between ‘Birchwood Parky’s Gold’ and ‘Golden Tiara.’
Many other excellent hostas are derived from H. nakaiana, either as sports or hybrid crosses. ‘Warwick Curtsey,’ a gold-margined small hosta, is the product of a cross with the well-known streaked parent ‘Dorothy Benedict’. ‘Candy Hearts,’ perhaps the most widely grown of H. nakaiana seedlings, and ‘Lemon Lime,’ which forms a greenish-gold mound, are both sports of H. nakaiana hybrids. ‘Pearl Lake’ is a dense, medium-sized hosta with heart-shaped leaves. ‘Allan P. McConnell,’ a H. nakaiana seedling, has dark green leaves with a white edge. ‘Birchwood Parky’s Gold,’ a cross between H. nakaiana and ‘Sunlight’, has chartreuse to golden yellow foliage. These are only a few of the many crosses and mutations that have H. nakaiana in their lineage.
The small, dense form of H. nakaiana makes it, and many of its progeny, an excellent edging plant. When in full bloom, a bed edged with H. nakaiana grabs the eye. Though it has now fallen somewhat out of favor with hybridizers and hosta enthusiasts, perhaps it deserves a second look.
The Cottage Gardener 