Problems Identifying Japanese Cedar Cultivated in the United States

Abstract

<jats:p>Japanese cedar [<jats:italic>Cryptomeria japonica</jats:italic> (Thun. ex L.f.) D. Don. (Taxodiaceae)] cultivars have become quite popular in the U.S. landscape and nursery industries. Their popularity is expected to increase as more attractive and adaptable horticultural selections gain recognition. Taxonomic problems include an inadequate inventory of selected variants cultivated in the United States, instability of names at the infraspecific taxonomic level, poor descriptions of the cultivars, and a lack of representative specimens and identification aids to help horticulturists identify unknown specimens. A study of <jats:italic>Cryptomeria japonica</jats:italic> cultivated in the United States is needed to address these problems.</jats:p>

Descriptions and a Key to Cultivars of Japanese Cedar Cultivated in the Eastern United States

“…The large number of cultivars selected of japanese cedar provided problems in segregation and the proper name to use (Rouse et al, 1997). This treatment provides new quantitative descriptions based upon field data, proper names with synonyms, and a taxonomic key to assist professional plantsmen in segregation and identification of cultivated taxa in the eastern United States.…”

Plate 371. Cryptomeria japonica

“…Another difference, commonly stated (and copied), namely that the Chinese taxon has only 2 seeds per scale (e.g. Cheng & Fu, 1978;Rushforth, 1987;Rouse et al, 1997) is certainly erroneous. The number of ovules is correlated with the number of teeth: at the base of each ovule one (very rarely two) tooth develops (Takaso & Tomlinson, 1989, ®gs.…”

“…This material does not differ from so-called C. fortunei or from C. kawaii in any of the characters mentioned, but of course nobody called it C. fortunei or any other name but C. japonica. It must be emphasized that Cryptomeria japonica is a genetically variable taxon, from which numerous cultivars have been selected, many of them well before Europeans got involved, as early reports and the occasional herbarium specimens testify (see also Rouse et al, 1997). Regional races are distinguished in Japan (Muto, 1975; see also Tomaru et al, 1994), but in view of the above mentioned uncertainties about provenances even in that country it is unlikely that genetic variation (still) correlates with chorology.…”

“…As we have seen, both Chinese and Japanese provenances were introduced, among which were forms with tortuous leaves now recognized as cultivars. Confusion has arisen as to the proper distinction and naming of the numerous cultivars currently known to be planted (Rouse et al, 1997). These authors and Tripp (1993) and Welch (1991Welch ( , 1993 compiled lists of current names, sometimes with synonyms.…”