A revision of Rhododendron. IV Subgenus Tsutsusi
A revision of Rhododendron subgenus Tsutsusi is presented: section Tsutsusi with 66 species is equivalent to series Azalea subser. Obtusum; and section Brachycalyx with 15 species includes some species previously placed in subser Schlippenbachii. One new species in section Tsutsusi, R. arunachalense Chamberlain & Rae, sp. nov., is described. Distribution maps are provided for most of the species.
Available from: Yuanwen Teng
- "It is not surprise to see different cultivars sharing the same name or the same plant called differently. On the contrary, a lot of work has been done on evergreen azalea morphology in Europe, including diversity of flower colors (Heursel, 1981), corolla size, number of stamens and percentage of plants with petaloid stamens (Heursel & Garretsen, 1989) and other taxonomic characters (Chamberlain & Rae, 1990). "
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ABSTRACT: Azaleas are among the 10 famous traditional flowers in China having a long cultivation history since the Tang Dynasty. Today, there are probably over 300 evergreen azalea cultivars preserved in different nurseries, all of which are usually classified as belonging to East, West, Summer and Hairy groups. Numerical taxonomy was carried out to determine the phenetic relationships between cultivars. Sixty six evergreen azaleas cultivars were studied based on 30 morphological characters (13 qualitative and 17 quantitative). Cluster analysis using unweighted pair group method with arithmetic average (UPGMA) and principal coordinate analysis (PCO) was performed by using NTSYS software. Mantel's test showed a good fitness between the cluster analysis and Euclidean distance matrix. The first three axes in PCO explained 49.94% of the total variation, and revealed that 14 characters, most of which are related to flowers, played an important role in numerical taxonomy. Both cluster analysis and PCO suggested that cultivars in the East and summer groups were distinct from other groups in the 4 group classification system based on the morphological characteristics, but the West and Hairy groups were closer when concerned primarily with phenetic relationships.
Available from: Akira Nakatsuka
- "In addition, our previous study of " sai-zaki " , which has choripetalous corollas that consist of 5 independent narrow petals, using old cultivars of R. macrosepalum suggested that one of the mutational cultivars might have had a similar mutation in the growth of the lateral organs in the transverse plane (Tasaki et al., in press). The " sai-zaki " cultivars are also found in a group of R. kaempferi, which grows from the extreme south to central Hokkaido in Japan (Chamberlain and Rae, 1990; Kumakura, 1976; Yamazaki et al., 1979; Wilson and Rehder, 1921; Yamazaki, 1996). This group includes various cultivars that have mutations in their floral organs, including narrow and staminoid petals, and their variation seems to be related to the floral identity genes. "
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ABSTRACT: The morphological traits of the floral mutation cultivars ‘Kagaribi’, ‘Kinshibe’ and ‘Kin-kujyaku’ of Rhododendron kaempferi that characteristically exhibit extremely narrow and/or staminoid petals were investigated. In addition, to confirm the causes of the mutations in these cultivars, the MADS-box C class AG gene homologues in R. kaempferi were isolated, and the MADS-box gene expression patterns in the floral organs of the wild-type plants and cultivars were analyzed. A morphological observation of the epidermis showed that the ‘Kagaribi’ and ‘Kinshibe’ cultivars formed staminoid flag petals and staminoid organs in whorl 2, respectively. The epidermal cells of the staminoid organs of whorl 2 in ‘Kagaribi’ and ‘Kinshibe’ resembled those of the stamens in whorl 3. In ‘Kin-kujyaku,’ the petals in whorl 2 and leaves were extremely narrow. The sepals in whorl 1 were absent, and the style in whorl 4 was split into 5 parts. The epidermal cells of the petals in whorl 2 in ‘Kin-kujyaku’ were dissimilar to the epidermal cells of the stamens in whorl 3. The deduced amino acid sequence of the isolated AG homologue from R. kaempferi was well-conserved among the AG orthologues. The expression levels of RkAG in whorl 2 to whorl 3 of ‘Kagaribi’ and ‘Kinshibe’ was approximately 27% and the same level, respectively. In ‘Kin-kujyaku,’ the expression pattern was similar to that of the wild type. These results suggest that the ‘Kagaribi’ and ‘Kinshibe’ floral mutations might be caused by the expression of RkAG in whorl 2.
Available from: Thomas Ranney
- "It has been applied to two sizable groups of Rhododendron species that bear little resemblance to one another. There are approximately 100 species of azaleas included in the evergreen sections Tsutsusi and Brachycalyx (Chamberlain and Rae, 1990), while in the deciduous section Pentanthera there are 16 to18 species also commonly known as azaleas. Besides these well-delineated groups, a few additional species are also called azaleas, as exemplified by R. vaseyi Gray, R. nipponicum Matsumura, R. schlippenbachii Maximowicz, R. albrechtii Maximowicz, and R. albiflorum Hooker. "
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ABSTRACT: A new species of deciduous azalea, Rhododendron colemanii R. Miller (Red Hills azalea), from the upper Coastal Plain of Alabama and Western Georgia, USA, has been characterized based on morphology, flowering phenology, habitat, native range, position in a molecular phylogeny, and genome size. Though specimens have previously been confused with Rhododendron alabamense Rehder or its hybrids, phylogenetic relationships based on sequences of the nuclear gene RPB2-I gene showed R. colemanii to be a coherent species in a clade of section Pentanthera G. Don along with R. luteum Sweet and the Southeastern U.S. azaleas R. atlanticum (Ashe) Rehder, R. austrinum (Small) Rehder, and R. calendulaceum (Michaux) Torrey. Flow cytometry showed R. colemanii to be, like the other azaleas in this clade, tetraploid. A detailed morphological description and Latin diagnosis are provided.
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