Collector’s Choice: Rhodea japonica

As a gardener in the chilled wash of the maritime Pacific Northwest, I have always been a bit skeptical of growing any plant I meet thriving in the summer-baked gardens of the southeastern states, which is where I first came upon Rohdea japonica. Since I first learned about it from the late J. C. Raulston of North Carolina, this species has become more familiar to me through its plethora of cultivars. I have developed a sincere admiration for its invincible nature and unique, varied ornamental qualities, which refuse to discriminate between the right and left coasts of our continent.

What Raulston shared with me was a division of an evergreen perennial from the Convallariaceae, a family including numerous well-known horticultural stalwarts, such as lily-of-the-valley (Convallaria), fairy bells (Disporum), Solomon’s seals (Polygonatum), and false Solomon’s seals (Smilacina). The year-round presence of Rohdea, however, reveals its relationship to other evergreen members of the family, such as Aspidistra and Reineckia.

As its specific epithet makes clear, Rohdea japonica is found throughout the Japanese archipelago. A primary component of the forest flora in heavily shaded sites, R. japonica produces dense rosettes of deep green, leathery, straplike leaves to 15 inches in height. In spring, tightly packed racemes of creamy white flowers appear near the base of the plants. These in turn become large succulent red or orange fruits that remain ornamental for many months. The only other species, R. watanabei, from Taiwan and mainland China, is somewhat larger in all aspects, and reportedly fragrant in flower—though I find it superficially quite similar to its Japanese cousin.

In traditional Japanese horticulture, R. japonica is known as o moto, which translates as “big base,” refering to its broad leaf base. During the prosperous and peaceful Edo Period (1603-1837), o moto came to be associated with long life and good fortune, with the species cultivated in containers near the entry to courtyards and homes. During this time, interest in breeding and selecting for colorful, contorted, ridged, dwarf, giant, or variegated plants of R. japonica rose to a fever pitch—to such a degree that the Japanese government prohibited its sale in 1852.

The cultivation of plants in containers is par for the course in Japan, and R. japonica proves no exception. In fact, in many ways it was the inspiration behind the tradition. The method of growing, displaying, and describing the variations in its 600 selected cultivars set the trend for numerous other genera of plants, from orchids to hepaticas, that have since become popular as containerized subjects throughout the country. Once again a legal commodity, societies and nurseries devoted to o moto abound, with vendors displaying the rarest and most expensive cultivars in locked cages.

Though named cultivars do have a certain collectible appeal and can be found in North American horticulture, the wild species possesses ornament enough to justify its inclusion in any garden found in USDA Zones 6 through 10. Hardy as far north as Boston on the East Coast and more than tolerant of the cool Pacific Northwest, R. japonica makes a superb low evergreen groundcover for shaded sites, while adding a vertical line that pleases the eye. 

TYPE OF PLANT: rhizomatous perennial groundcover FAMILY: Convallariaceae ORIGIN: Japan, southwest China HEIGHT/SPREAD: 10 in./8 in. LEAVES: deep green, straplike, leathery, forming rosettes; numerous cultivars have ridged, variegated, or otherwise peculiar leaves FLOWERS: creamy white or greenish white, bell shaped; borne in racemes in early spring FRUIT: red or orange plump berries lasting several months

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