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Peter Del Tredici and Jianhua Li

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Michael S. Dosmann and Peter Del Tredici

The 1980 Sino-American Botanical Expedition (SABE) to the Shennongjia Forest District, Hubei Province, China was the first botanical collecting trip by American scientists to that country since 1949. This collaborative venture with Chinese botanists yielded 2085 herbarium and 621 germplasm collections from the species-rich region. Our analysis tracked the fate of the SABE germplasm after its introduction to North America and represents one of the few case studies of its kind. Two hundred and fifty-eight of the original germplasm collections still survive and are in cultivation in at least one of 18 botanical institutions. Yet 115 of these (45%) are represented by a single accession growing in a single location, which suggests that the plant introduction process is more tenuous than is generally assumed. The scientific value of documented wild germplasm warrants that careful measures are in place to ensure that significant collections do not vanish. This case study outlines steps that can be taken throughout the introduction process (from propagation to distribution and follow-up) to prevent any such loss. In particular, the role of data sharing among institutions is highlighted as a means of identifying collection uniqueness, and assessing environmental adaptability and invasiveness.

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Jianhua Li, Michael S. Dosmann, Peter Del Tredici, and Susyn Andrews

Sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA were used to examine genetic divergence of the two species of katsura [Cercidiphyllum japonicum Sieb. & Zucc. and Cercidiphyllum magnificum (Nakai) Nakai] and four clones of weeping katsura (`Amazing Grace', `Tidal Wave', `Pendulum', and `Morioka Weeping'), and to characterize the affinity of these weeping katsura to both species. Our results indicate that C. japonicum and C. magnificum are genetically distinct, supporting the recognition of them as separate species. Based on our DNA sequence data and morphological evidence, all weeping selections are phylogenetically derived from C. japonicum, not C. magnificum; nor are they of a hybrid origin between C. japonicum and C. magnificum. We propose the new cultivar-group Cercidiphyllum japonicum Weeping Group to include all katsura clones of weeping or pendulous habit, and recognize the cultivar epithet `Morioka Weeping' and its application to the excurrent and upright clone obtained from Japan and distributed in North America by the Arnold Arboretum.

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Jianhua Li, Jeremy Ledger, Peter Del Tredici, and Donglin Zhang

The identity of heath-leaved cypress is controversial. In this study nucleotide sequences of nuclear ribosomal DNA were used to identify heath-leaved cypress (Chamaecyparis `Ericoides') species. Sixteen individuals were sampled representing the five species of Chamaecyparis, `Ericoides', and four other genera of Cupressaceae (Cupressus, Fokienia, Juniperus, and Thuja). The results placed `Ericoides' unequivocally to Chamaecyparis thyoides, supporting a conclusion derived from wood anatomy. This study supports the usefulness and integrity of using molecular data to identify the genetic affinity of cultivars that are morphologically different from the parent species.