Cryptomeria japonica Seeds | Japanese Cedar
LATIN NAME: Cryptomeria japonica
COMMON NAME: Japanese Cedar, Sugi, Japanese Redwood
Plant Profile
Cryptomeria holds a single species, and its closest relative is the bald cypress of North America, a pairing that surprises anyone who assumes it must be related to the cypresses it resembles. Both sit in the same small group inside Cupressaceae, the family that absorbed the old Taxodiaceae when the conifers were re-sorted.
Seedlings and shaded shoots carry sharp awl-shaped needles; older, sunlit growth carries scale-like leaves packed along the twig, so both leaf forms can sit on one tree. Growers use the difference: cuttings taken from juvenile material root and grow more vigorously, and the weeping clone sold for gardens keeps the juvenile form for life.
Material from southeastern China has shorter needles and smaller cones than the trees of Japan, and botanists have argued for a century about what that means. Some treat it as Cryptomeria fortunei, others as a variety of the Japanese species.
Forestry relies on cuttings from selected trees, and somatic embryogenesis from immature seed has been worked out for the species, letting one elite tree be multiplied in quantity. Clonal planting produced the uniform stands.
Science & Biotechnology
Heartwood extractives give the timber its rot resistance. Cryptomeria heartwood carries the abietane diterpenoid ferruginol, together with the sesquiterpene cryptomeridiol, a compound named for the tree itself. Ferruginol has documented antimicrobial and termite-deterrent activity, which is the chemistry behind a light wood that lasts.
Two proteins carry most of the pollen’s allergenicity. Cry j 1 is a pectate lyase and Cry j 2 a polygalacturonase; both sit in the pollen wall, and both are used as the standards against which allergy tests and immunotherapy extracts are calibrated. Breeding programmes have selected trees with lower pollen output and later flowering, but the planted landscape is already vast.
Uses & Benefits
Cultivation of this tree is older than any garden catalogue, and its uses follow the wood.
The timber is light, straight-grained and slow to rot, which made it the wood of shrines and temples and of the casks used in brewing. The most famous commitment to it is the periodic rebuilding of a major shrine, where the structures are taken down and raised again on a fixed cycle of years using the same species.
Garden use follows two lines. The juvenile-foliage clone grown as a hedge keeps its soft needles and turns bronze in winter, while the rounded dwarf clones stay compact enough for a rock garden or a large pot; the named form Globosa Nana is among the smallest.
The social cost of the planting boom is counted in clinics. Thinning mature stands, removing trees close to housing and planting low-pollen varieties are the tools in use, and the species is now a case study in what happens when a forestry programme and public health collide.
Growing from Seed
Cryptomeria seed is small and light and loses vigour in storage, so sow it in the season it is collected. Surface sow onto a fine, moist mix of one part peat-free compost, one part leaf mould and one part grit, and press the seed down rather than burying it.
In its native range the species contends with a bark-boring beetle and with needle blights; elsewhere it is remarkably free of trouble. Wind is the greater enemy, since the roots are shallow and the crown catches a lot of air, and the winter bronzing of juvenile foliage is normal rather than injury.
Our Take
Plant the Chinese form, Cryptomeria fortunei, beside it to compare cone size, and give bald cypress the wet ground at the bottom of the garden. Lawson cypress makes a similar conical outline on a smaller scale.
Related Reading
Continue exploring with these related plants: