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Ryan N. Contreras, John M. Ruter, and Brian M. Schwartz

. Polyploidy in gymnosperms is rare ( Ahuja, 2005 ; Khoshoo, 1959 , 1961 ), but following the work of Blakeslee and Avery (1937) , there were a number of studies that attempted to induce polyploidy. The primarily goal of those studies was to develop more

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Robert J. Rouse, Paul R. Fantz, and Ted E. Bilderback

Japanese cedar [Cryptomeria japonica (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 Cryptomeria japonica cultivated in the United States is needed to address these problems.

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Jules Janick, Christiane Cabral Velho, and Anna Whipkey

Mature seed weight of loblolly pine (Pinus taeda L.) averaged 25 mg (dry weight), of which 55.0% was seedcoat, 38.5% megagametophyte, and 6.4% embryo. Fatty acid (FA) content (dry-weight basis) was 17.5% for whole seed, 0.4% for seedcoat, 36.2% for megagametophyte, and 51.2% for embryo. Distribution of FAs (16:0; 18:0; 18:1; 18:2; 18:3 Δ5,9,12; 18:3 Δ9,12,15; 20:0; and 20:3) differed in seedcoat, megagametophyte, and embryo, but 18:2 was the predominant FA in all tissues. Seed development was analyzed for 110 days from 25 July, the year following pollination. Embryos could be macroscopically observed on or about day 30. Embryo dry weight, length, and FA accumulation increased until about day 50 and then remained constant. Embryo density decreased from day 30 to 50 and then stabilized at ≈1.0366 g·ml-1 or 10% sucrose equivalent. Excised zygotic embryos did not germinate in vitro until after day 51; germination increased linearly after this date, reaching 80% by day 72.

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Robert J. Rouse, Paul R. Fantz, and Ted E. Bilderback

Japanese cedar, Cryptomeria japonica (Thunb. ex L.f.) D. Don [Cupressaceae Bartling, formerly assigned to Taxodiaceae Warm.] is increasing in popularity as a landscape plant in the eastern United States. A taxonomic study of cultivars grown in the eastern United States was conducted. Forty-five cultivars were recognized. Each cultivar bears synonymy, a quantitative morphological description newly described from field data, herbarium vouchers, references to original literature and observational notes. A glossary of taxonomic terms relevant to Cryptomeria is presented. A taxonomic key is presented for segregation of cultivars that should assist professional plantsmen in identification of taxa cultivated in the eastern United States.

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Manuela Baietto and A. Dan Wilson

occurred on sapwoods of angiosperm species (hardwoods) than on conifer species (gymnosperms) during the first and to a lesser extent in the second year of decay. Treatment effects on mean percent dry weight loss of wood blocks (the measure of decay) were

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Jason D. Lattier, Hsuan Chen, and Ryan N. Contreras

one gymnosperm ( Table 1 ). Plants were grown in a temperature-controlled glasshouse at Oregon State University. Although variable growth conditions would likely affect the quality of roots for cytology, all plants were grown under the same standard

Open access

Ying Yang, Xian-Ge Hu, Bingsong Zheng, Yue Li, Tongli Wang, Anket Sharma, Huwei Yuan, and Jian-Feng Mao

different stresses to conifers and other gymnosperms ( Li et al., 2017 ; Liu and El-Kassaby, 2017 ). miRNAs generally bind to the 3′-UTR (untranslated region) of their corresponding target mRNAs and restrain protein production by destabilizing the mRNA and

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Jack B. Fisher, Anders Lindström, and Thomas E. Marler

floriculture industries. The columnar stem of arborescent species lacks thin twigs found in other gymnosperms and is therefore classified as a pachycaulous tree ( Stevenson, 1980 ). Cycads are often grouped with palms that are also pachycaulous ( Norstog and

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Ting Liao, Guobin Liu, Liqin Guo, Ye Wang, Yanwu Yao, and Jun Cao

Plants in the Cupressaceae family, which are widely distributed in the southern and northern hemispheres, are the only gymnosperms distributed worldwide (Zheng and Fu, 1978). P. orientalis , a monotypic genus belonging to Cupressaceae, is one of