Flowering Events Research Articles

TIME, SPACE, LIGHT AND DARKNESS IN THE METABOLIC FLARE-UP OF THE SAUROMATUM APPENDIX*

SUMMARY In order to arrive at a better understanding of the flowering events in certain arum lilies, an effort has been made to integrate the relevant information provided by plant physiologists, naturalists, and plant biochemists with our own recent experiments. In Sauromatum guttatum Schott, the metabolic flare-up which, on the first day of flowering, occurs in the so called appendix of the inflorescence, is triggered by an agent (Van Herk's calorigen) that arises in the male flower primordia when these are exposed to the proper regime of light and darkness. A single, 5 to 6 hour exposure to darkness of an inflorescence kept in constant light suffices to induce the flare-up, a peak in heat- and CO2-production occurring about 40 to 45 hours after the beginning of the “dark shot”. Repeated exposures to darkness, at 24-hour intervals, shorten both the 40 to 45-hour lag-time and the critical length of each dark period, so that good responses occur after about 36 hrs. with a series of dark shots of 2 to 3 hours duration. The available evidence indicates that the site for perception of the second effective dark shot is in the appendix. After a single 6-hour dark shot, amputated appendices still develop heat and smell, provided the amputation is carried out at least 8 to 9 hours after the end of the dark shot. This indicates that the active principle formed in the male flower primordia as the result of the dark shot is not immediately released into the appendix. However, distribution in the appendix must be fast, since the various parts of the latter (base, middle and tip) heat up almost simultaneously, even though they do not display demonstrable differences in true lag-time, i.e., in the period between the release of the triggering compound and the peak in metabolic activity; injection of extracted calorigen into properly treated appendix-sections always leads to a peak in metabolic activity about 30 hours later. In intact inflorescences, amputation or wounding of the spathe leads to a metabolic flare-up 36 hours later. The implications of the uncovered facts are briefly discussed.

Seasonal succession of bloodsucking Diptera in Wisconsin during 1965.

Abs:ract : The seasonal sequences of species of Culicidae, Simuliidae, Tabanidae and several other bloodsucking Diptera as determined by CO&rap c01kcti0n.s are reported, as are the dates of first flowering of a number of plant species. Insect species that appeared th- p earliest as bloodseeking females were the mosquitoes, Cuiiseta inoranta and Ano@& punctipennis, and the black flies, Cnephia tamiatifrons and Simulium johannseni, each of which was active before the first flowering of such earlyflowering plants as Juneberry, wild plum and pin cherry. Considered as groups, mosquitoes of genera that mostly hibernate as adults (Culiseta, Ano@&s, C&x) were first to appear zs bloodseeking females followed closely by the Simuliidae, then the eariier aedine mosquitoes, and, finally, the Tabanidae and Ceratopogonidae. Among the Tabanidae, species of Chqsops and f&/bon&a appeared much earlier than species of Tabanxc. In 1965 a trapping program for bloodsucking Diptera was started as part of a study of the host relationships of bloodsucking arthropods, their roles in the ecology of arboviruses in Wisconsin, and as pests in recreational and agricultural lands. In this program we had,the following objectives: 1. To determine the seasonal sequence of bloodseeking adults of the families Culicidae, Ceratopogonidae, Simuliidae, and Tabanidae. Such information, in conjunction with data on host-preferences, would be useful both in determining with which arthropod species a vertebrate might have had contact before acquiring an arbovirus infection, and in revealing the sequence of problems posed by the various species as biting pests in recreational areas. 2. To determine how closely the seasonal appearances of the adults parallel those of flowering and other phenological botanical events. Many variables are involved. But if a predicatable parallel exists, easily observed plant events might serve as useful indicators of the progress of the season, not only for entomologists, but also for nonentomologists such as park and forest administrators who must deal with problems posed by biting insects. 3. To establish a continuing surveillance of arboviruses in arthropods-this surveillance to

Some long‐term means from The Phenological Reports (1891–1948) of the Royal Meteorological Society

AbstractThe Phenological Reports 1891–1948 of the Royal Meteorological Society are discussed; interpolated values in floral records have been re‐calculated, and 58‐yr district and British Isles weighted means, and annual differences from these, have been calculated for 11 flowering events. 20‐yr means and differences have been similarly calculated for a further 14 events, and the former approximately corrected to the 58‐yr means. For 11 main flowers in The Phenological Reports, the mean difference in flowering dates between south and north Britain was 21 days later for a distance of some 400 mi farther north. Extremes of earliness and lateness have been tabulated for the British Isles weighted means for these 11 flowers over the years 1891‐1948. Extreme earliness averaged 17‐7 days and extreme lateness 17‐1 days, but while extremes of earliness were fairly constant throughout the year or possibly became a little greater for summer than for spring flowers, extremes of lateness were much greater for spring than for late summer flowers. These differences are directionally in keeping with the finding of Hawke (1941) that in the winter months abnormally low temperatures are much more extreme than abnormally high values, while in summer the abnormally high values are more extreme than the exceptionally low. The standard deviations for the annual values of the British Isles weighted means are also given, and averaged 7‐0 days for the 11 main flowers.