The spread of invasive taxa, including Lythrum salicaria, Typha X glauca, Myriophyltum spicatum, Phalaris arundinacea, and Phragmites australis, has dramatically changed the vegetation of many wetlands of North America. Three theories have been advanced to explain the nature of plant invasiveness. Aggressive growth during geographic expansion could result because 1) growth is more favorable under new environmental conditions than those of resident locales (environmental constraints hypothesis); 2) herbivores may be absent in the new locale, resulting in selection of genotypes with improved competitive ability and reduced allocation to herbivore defenses (evolution of increased competitive ability hypothesis); and 3) interspecific hybridization occurred between a new taxon and one existing in an area, resulting in novel phenotypes with selective advantages in disturbed sites or phenotypes that can grow under conditions not favorable for either parent (introgression/hybrid speciation hypothesis). A review of published literature found few studies that compare the growth and dynamics of invasive populations in their new range versus those in historic ranges. However, there is evidence that hydrologic alterations could facilitate invasions by Typha × glauca and Phalaris arundinacea and that increased salimty promoted spread of Typha angustifolia (parental taxon) and Phragmites australis, The potential for reduced herbivory causing aggressive growth is greatest for Lythrum salicaria. Introgressive hybridization is potentially a cause of invasiveness for all five species but has been established only for Typha × glauca and Lythrum salicaria.

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Self incompatibility was investigated in the hexaploid garden chrysanthemum, a member of Compositae. Nine sibling clones selected from a highly compatible cross were all self incompatible. 14.8% of the crosses between these sibs in diallel were compatible, but one sib, 67-111-42, accounted for 10 of the 12 compatible crosses. 67-111-42 was also more compatible than the remaining 8 sibs in crosses to other closely related plants. Crosses of the 9 sibs to 12 unrelated tester clones indicated that none were male or female sterile. Inbreeding via pseudocompatibility was successful in increasing homozygosity at the S loci. The percentage of compatible crosses obtained in 3 sib diallels of I 2 clones from crosses of 67-111-42I 1 plants approached that of the original 9 × 9 diallel, but no one individual accounted for most of the compatible crosses. It was possible to separate the 9 sibs into 9 incompatibility patterns from the pollinations made in this study. The evidence suggests that the self-incompatibility reaction in the garden chrysanthemum is sporophytic and involves more than 1 locus.

Three new Chrysanthemum ·hybrida, garden chrysanthemum cultivars: Red Daisy, White Daisy, and Coral Daisy, are the first in the Mammoth TM series that are advanced interspecific hybrids derived from an open-pollinated cross between hexaploid C. weyrichii (Maxim.) Tzvelv. · C. ·grandiflora Tzvelv. These cultivars are backcross or inbred derivatives of the original interspecific F 1 hybrids. All three cultivars are U.S. Department of Agriculture Z3b (-34.4 8C to -37.2 8C) winter-hardy herbaceous perennials exhibiting a shrub habit with the cushion phenotype. Additional traits exhibited by these three cultivars are butterfly attractants, frost tolerance of the flowers, and genetic 'self-pinching.' These Mammoth TM cultivars are clonally propagated, virus indexed, protected by U.S. Plant Patents and Canadian Plant Breeder's Rights, and are available from the North American exclusive licensee Ball Seed Company.Chrysanthemums (Chrysanthemum ·grandiflora Ramat.; =Dendranthema · grandiflora Tzvelv.) are popular cut flowers, potted flowering plants, and perennial garden favorites worldwide with thousands of cultivars available (Anderson, 2006). Garden chrysanthemums are the number one herbaceous perennial in the United States, with a wholesale farmgate value of $141.845 million in (U.S. Dept. Agr, 2006. Numerous factors contribute to the long-term popularity of garden chrysanthemums, including fall flowering (most cultivars are obligate shortday plants), a wide range of flower types and colors, distinct plant habits (upright, cushion, groundcover), and winter hardiness (particularly for northern gardeners

Commercial garden and greenhouse chrysanthemums [Dendranthema ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum xmorifolium Ramat.)] are facultative short-day plants for flower bud initiation, obligate short-day plants for flower bud development, and are categorized into short-day response groups. Flower initiation can be delayed by high night temperatures. Recent research has identified true day-neutral genotypes. The purpose of this investigation was to test environments for selecting genotypes that are both day-neutral and heat-delay insensitive. One greenhouse and 18 garden genotypes were selected. A series of environments were used to select for day-neutral genotypes and then differentiate between these genotypes for heat delay insensitivity: short days, long days/red light, long days/far red light and high temperatures, and natural day lengths under field conditions. Day-neutral selections from these environments were then grown in a fifth environment of long days/continuous far red and red light with high temperature. Data were collected on the number of days to first and third flower, long day leaf number, stem length, number of strap-shaped leaves subtending the terminal flower, internode lengths, number of nodes with axillary branching, and flower bud development of the first to the sixth flowers. Genotypes required 3 to 8 weeks for complete flower bud initiation/development. Flowering responses in the first four environments were highly significant for both the first and third flowers. Genotypes ranged from obligate short-day to day-neutral for the first six flowers. Three day-neutral genotypes were selected that differed significantly for all traits in the fifth environment; flower bud development with the first six flowers occurred with only one genotype, 83-267-3. Broad sense heritability estimates ranged from h2 = 0.75 for number of nodes with axillary branching, h2 = 0.79 for long day leaf number and number of strap-shaped leaves, to h2 = 0.91 for stem length. An ideotype for day-neutral and heat-delay-insensitive garden chrysanthemums was developed for use in breeding programs.