The current Cucumis taxonomic classification places C. hystrix Chakr. in subgen. Cucumis based on its morphological similarities to cucumber (C. sativus L., 2n = 14). However, the chromosome number of C. hystrix was identified as 2n = 24, the same number as in subgen. Melo. Cucumis hystrix is therefore considered the first wild Cucumis species of Asiatic origin possessing 12 basic chromosomes. Thus, any research regarding its biosystematics would challenge the basic chromosome number and geographic location theories that govern the current taxonomic system. The production of the amphidiploid species (Cucumis ×hytivus Chen and Kirkbride, 2n = 38) obtained from the cross between C. hystrix and C. sativus and subsequent chromosome doubling would provide an effective means of investigating the relationship between Cucumis species with two different basic chromosome numbers. Thus, RAPD markers were used to study the taxonomic placement of C. hystrix and its interspecific hybrid with cucumber. Of the 220 arbitrary primers screened, 31 were used for analysis where 402 (96.3%) fragments were polymorphic among the germplasm examined. A UPGMA-based cluster analysis partitioned 31 accessions into two main groups [C. sativus (CS) and C. melo (CM)]. Under the similarity coefficient threshold of 0.23, these two groups can be further divided into five clusters with C. hystrix, C. ×hytivus, and C. sativus as separate clusters in the CS group. A modified taxonomic system is proposed based on these results and findings of a previous chloroplast DNA analysis with the genus Cucumis containing subgen. Cucumis with three species and subgen. Melo with six series.
Fei-Yun Zhuang, Jin-Feng Chen, Jack E. Staub and Chun-Tao Qian
Arthur O. Tucker
Paul R. Fantz
Liriopogons (Liriope, Ophiopogon) are versatile landscape plants with a complexity of taxonomic problems. A taxonomic revision of liriopogons cultivated in the United States is needed; one that includes an inventory of taxa, quantitative descriptions of species and cultivars, keys and other aids for segregation and identification of taxa, documentation of taxa with vouchers deposited in herbaria, and establishment of a living germplasm collection that can serve as a standard for the nursery/landscape industries.
Geoffrey C. Denny and Michael A. Arnold
The appropriate taxonomy and nomenclature for plant taxa (taxonomic groupings) are often overlooked by the nursery industry and may seem of little importance. However, names frequently do not reflect the most current taxonomic classification. This
Paul R. Fantz
A taxonomic revision of liriopogons (Liriope Lour., Ophiopogon Ker-Gawl) cultivated in the United States is in progress at North Carolina State Univ. Germplasm was obtained from nurseries, botanical gardens/arboreta, and private collectors. Nearly 17% of the germplasm was misidentified to genus; nearly 36% misidentified to species; and nearly 14% received under one name from one source contained mixed germplasm. Preliminary analysis of data indicate a minimum of five species of Liriope and eight species of Ophio-pogon are in cultivation. Six additional taxa have not flowered. Polygonal graph analysis was used to visualize biometrical data and observe relationships among taxa. Additional taxonomic publications for segregation of genera and species of liriopogons, including an inventory of taxa, quantitative descriptions, illustrations, and keys, are in progress.
Monica L. Elliott, J.A. McInroy, K. Xiong, J.H. Kim, H.D. Skipper and E.A. Guertal
examined microbial community diversity in general, taxonomic diversity within these communities has not been examined except in a broad sense based on semiselective media and techniques for particular bacterial groups. Thus, it is not known which culturable
Chao Yu, Le Luo, Hui-tang Pan, Yun-ji Sui, Run-hua Guo, Jin-yao Wang and Qi-xiang Zhang
of chromosomes can rationalize and accelerate the exploitation of genetic variation from wild relatives of crops ( Baenziger et al., 2006 ). What is more, the results might be helpful in elucidation of some taxonomical problems and relations between
Alice Le Duc, Robert P. Adams and Ming Zhong
Van Melle (1947) proposed that juniper cultivars of the Pfitzer Group were of hybrid origin and ascribed the name Juniperus ×media Melle. This purported hybrid of J. chinensis L. × J. sabina L. has not been accepted unanimously by the horticultural community. Random amplified polymorphic DNAs (RAPDs) were used to analyze and establish new evidence for the hybrid origin of the Pfitzer Group, using both parents and seven cultivars of the Pfitzer Group. Principal coordinate analysis (PCO) of 122 RAPD bands demonstrated that samples of J. chinensis cluster tightly together, as do the J. sabina samples. Cultivars of the Pfitzer Group lacked affinity with either species, but stood apart as a distinct cluster. The data support Van Melle's conclusion that the Pfitzer Group is separate from J. chinensis and indicate hybrid origin from parents J. chinensis and J. sabina. We recognize Juniperus ×pfitzeriana (Späth) Schmidt [Pfitzer Group] as the correct name for cultivars of Pfitzer junipers. Juniperus ×media, proposed by Van Melle, was rendered illegitimate because of the earlier name J. media V.D. Dmitriev.
Paul R. Fantz and Donglin Zhang
Horticultural Science in the past quarter of a century has been shifting to increased emphasis on ornamental plants due to the growth of the modern green industry. Numerous species are being introduced into the exterior and interior landscapes. For popular species, the cultivar, as defined by the International Code of Nomenclature for Cultivated Plants (ICNCP), has become the basic taxon of cultivated plants. Named ornamental plant cultivars are rising at a rapid rate creating identification and segregation problems in the landscape industry, nurseries, botanic gardens, arboreta, and breeding programs. Government regulations and legal issues are beginning to infringe as solutions to the problems. There is a critical need existing for taxonomic research on ornamental cultivars utilizing classical morphological analysis supplemented with modern biotechnological techniques (e.g., anatomical, chemical, cytological, DNA, Sem analysis). Taxonomic research on existing and newer cultivars can provide quantitative botanical descriptions, keys of segregation, correct identification, determination of correct names and synonymy, improved cultivar documentation, and grouping of similar cultivars in large complexes. The taxonomic research is basic science that has immediate applied application within the horticultural society, and results should be published in the journals of ASHS.
M.G. DeWald, G.A. Moore and W.B. Sherman
Genetically characterized isozyme loci are useful for taxonomic studies. In an initial study a few Ananas genotypes were used to determine which enzyme systems would give well-resolved banding patterns on starch gels. The enzyme-staining systems that resulted in well-resolved banding patterns were used to survey more Ananas genotypes to identify and characterize isozyme polymorphism. Genetic studies were performed using seedling populations to determine the basis of variability observed among genotypes. Two peroxidase loci and three phosphoglucomutase loci were identified and characterized. Information from these studies, was used to formulate a system by which species and plant introductions could be identified and distinguished.