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This review assesses the state of our knowledge about comparative seed shadows. Using data presently available in the literature, I compare the slopes (on a log-linear scale) of seed shadows for plants with different morphologically characterized modes of dispersal. The seeds of many species have no evident morphological adaptation for dispersal and seem to achieve only short-distance dispersal. Seed shadows for herbaceous species with devices for wind have flatter slopes and more distant modes and maxima than those of ballists, which in turn exceed those with no special devices. Seed shadows for wind-dispersed trees and shrubs had similar or steeper slopes than those for vertebrate-dispersed species in this sample. Species with poor mechanisms for dispersal in space only sometimes had the capacity for better dispersal in time (dormancy). Although some species exhibited seed shadows sufficiently steep to be predicted to colonize new-habitat in a ‘front’ or phalanx pattern, actual colonization patterns must reflect many other factors.

We investigated germination, seedling emergence and seed persistence of the invasive moth vine (Araujia sericifera Brot.) under controlled and field conditions in south-eastern Queensland. Fresh seed showed high viability (99.5%) and germinated readily, with 97.2% of all recorded germinations occurring within 14 days. Mean germination rates ranged from 74 to 100% across the range of temperature (10/20°C, 15/25°C and 20/30°C alternating 12-h thermoperiods) and light (0- and 12-h photoperiods) treatments. Germination was significantly reduced only under cool, dark conditions. In a 24-month field experiment, seedling emergence was greatest for seeds buried at 1 cm (mean = 96.3%), intermediate for seeds buried at 5 cm (mean = 62.7%) and least for surface-sown seeds (mean = 30.7%). Seed persistence under field conditions was low, declining rapidly to 3.9% at 6 months and to 0.67% at 24 months. Moth vine’s capacity to germinate readily and the rapid depletion of seeds under field conditions indicate that the species has a transient seed bank in south-eastern Queensland. In an additional experiment testing the capacity of seeds for secondary dispersal by water, the mean floating time of seeds was 15.4 days, suggesting that water could act as a secondary dispersal vector, contributing to long-distance dispersal. We recommend that surveillance methods for detecting moth-vine populations should consider both water-flow patterns and wind direction.

Dicranum flagellare Hedw. depends primarily on the dispersal ofasexual brood branch- es to colonize disturbance gaps on decaying logs. Forest slugs appear to be a significant dispersal vector. Propagules became entrapped in the slug secretions and were deposited in the slime trail. Field and laboratory trials demonstrated that slugs can detach and transport brood bodies at least 23 cm from the colony, although the mean dispersal distance was only 3.7 cm. The presence of slug secretions did not affect propagule germination rate, but did significantly increase adherence to the substrate.

MYSTER, R. W. (Terrestrial Ecology Division, University of Puerto Rico, San Juan, PR 00936), AND S. T. A. PicyErr (Institute of Ecosystem Studies, Mary Flagler Cary Arboretum, Millbrook, NY 12545). Effects of palatability and dispersal mode on spatial patterns of trees in oldfields. Bull. Torrey Bot. Club 119: 145-151. 1992.-The spatial patterns of tree stems in 480 plots were examined on a series of ten experimental oldfields adjacent to an old growth forest over a 31 -year period. Tree stem density decreased exponentially with distance from the forest edge early in succession. Later in succession the predictive power of the negative exponential model decreased, suggesting that processes such as animal seed dispersal within a field become important. Species palatable to herbivores were denser than unpalatable species close to the forest edge which implies that consumer pressure originates in the field rather than in the forest. Stems of all species were clumped on the scale of the 1 m2 plots. However, stems of bird-dispersed species showed the highest degree of clumping as expected if perches serve as recruitment foci. Results suggest that spatial patterns of tree seedlings in oldfields are significantly influenced by successional age, herbivory, dispersal vector and proximity to forest edge.

The timing of seed fall was studied in a guild of seven ant-dispersed forest herbs in NE-Zealand, Denmark. It is demonstrated, that the seed fall curves of Carex pilulifera, Melica uniflora and Luzula multiflora are remarkably different, representing logistic, hyperbolic, and linear relationships, respectively. The influence of environmental factors, and the significance to dispersal and predation, is discussed. It is suggested, that the three types of curves represent different strategies of seed fall. Simple, and explanded models of seed fall rate indicate that the density of seeds available to ants was more than 20 times greater for C. pilulifera than for M. uniflora. The observed phenological overlap of dispersal periods in the guild conformed to random expectations. Thus, the competition hypothesis was rejected, as there were no indications of a shift in phenology resulting from interspecific competition for the dispersal vector.

I. Introduction.- A. The Place of Dispersal in the Chain of Life.- B. Limitations and Objections.- C. History and General Literature.- II. General Terminology.- III. The Units of Dispersal.- Vegetative Parts in Dispersal and False Vivipary.- IV. The Relation Between Flowers, Seeds and Fruits.- A. Seed and Fruit.- B. Morphological Fruit Systems.- C. Morphological Interaction Between Fruit and Flower.- 1. General.- 2. Position.- 3. Monovuly and Monospermy.- 4. Inferiority and the Calyx.- D. Inadequacy of Current Fruit Terminology.- V. Ecological Dispersal Classes, Established on the Basis of the Dispersing Agents.- A. General.- B. Invertebrates.- C. Fishes and Ichthyochory.- D. Reptiles and Saurochory.- E. Birds and Ornithochory.- 1. Epizoochory by Birds.- 2. Synzoochorous Bird Diaspores.- 3. Endozoochory.- Non-adapted Diaspores.- Adapted Diaspores.- The Syndrome of Bird Diaspores.- Oil-containing Fruits.- Remarks on Evolution.- Mimesis (Imitative Seeds).- F. Mammals and Mammaliochory.- 1. General.- 2. Dyszoochory and Rodents.- 3. Accidental Endozoochory.- 4. Adaptive Endozoochory.- Ungulates.- Bats and Chiropterochory.- Primates.- Various Mammals.- G. Ants and Myrmecochory.- H. Wind and Anemochory.- 1. General.- 2. Dust Diaspores.- 3. Balloons.- 4. Plumed (Comose) Diaspores.- 5. Winged Diaspores.- 6. Tumbleweeds.- 7. Wind-Ballists (Anemoballists).- J. Water and Hydrochory.- 1. General.- 2. Rain Wash (Ombrohydrochory).- 3. Rain-Ballists.- 4. Submerged Transport in Water.- 5. Floating Diaspores.- K. Epizoochory, Transport on the Outside of Animals in General.- 1. Diverse Origins.- 2. Trample Burrs.- 3. Water Burrs.- 4. Burrs and Other Adhesives Above Ground Level.- 5. Other Spiny Fruits.- L. Autochory, Dispersal by the Plant Itself.- 1. General.- 2. Active Ballists.- 3. Passive Ballists.- 4. Creeping Diaspores.- M. Barochory, Dispersal by Weight Only.- N. Retrospective View.- VI. Dispersal Strategy and the Biocoenosis.- A. Atelochory.- 1. General.- 2. Synaptospermy.- 3. Basicarpy.- 4. Geocarpy.- B. Polychory and Attendant Phenomena.- 1. General.- 2. Heterodiaspory.- 3. Tachyspory.- C. Concluding Remarks on Synecology.- 1. Deserts.- 2. The Rain Forest.- 3. Epiphytes.- 4. The Arctic.- 5. Island Floras.- 6. Plant Sociology and Dispersal.- 7. Coordinated Dispersal.- VII. Establishment.- A. General.- B. Fixation.- C. Vivipary.- D. Germination.- 1. General Importance.- 2. Span of Life and Dormancy.- 3. Influence of Dispersing Agents and Other Stimuli.- VIII. The Evolution of Dispersal Organs in General.- A. Aims.- B. Isosporous Pteridophytes.- C. Heterosporous Pteridophytes with Free Megaspores.- D. Pteridosperms.- E. Gymnosperms (or Pre-Angiosperms).- F. Angiosperms.- 1. The Seed.- 2. The Seed Escaped from Angiospermy.- 3. The Sarcotesta Maintained in Conventional Fruits.- 4. Arilloids.- 5. Pulpa.- 6. The Pericarp Fruit.- Shift of Function.- Autonomous Cycles.- Further Evolutionary Influences and Processes.- IX. Ecological Developments in Leguminous Fruits.- X. Dispersal and the Evolution of Grasses.- A. Comparison with Cyperaceae.- B. Return to Gramineae (i.c. Oryzeae).- C. Bambusoid Grasses.- D. Bamboos.- E. Open Plains and Higher Grasses.- F. Some More Remarks on Awns and on Establishment.- G. Retrospective Views.- XI. Man and His Plants in Relation to Dispersal.- References.- Index of Scientific Plant Names.- Index of Scientific Animal Names.

Birds are thought to be important vectors underlying the disjunct distribution patterns of some terrestrial biota. Here, we investigate the role of birds in the colonisation by Ochetophila trinervis (Rhamnaceae), a vascular plant from the southern Andes, of sub-Antarctic Marion Island. The location of O. trinervis on the island far from human activities, in combination with a reconstruction of island visitors’ travel history, precludes an anthropogenic introduction. Notably, three bird species occurring in the southern Andes inland have been observed as vagrants on Marion Island, with the barn swallow Hirundo rustica as the most common one. This vagrant displays long-distance migratory behaviour, eats seeds when insects are in short supply, and has started breeding in South America since the 1980s. Since naturalised O. trinervis has never been found outside the southern Andes and its diaspores are incapable of surviving in seawater or dispersing by wind, a natural avian dispersal event from the Andes to Marion Island, a distance of >7500 km, remains the only probable explanation. Although one self-incompatible shrub seems doomed to remain solitary, its mere establishment on a Southern Ocean island demonstrates the potential of vagrancy as a driver of extreme long-distance dispersal of terrestrial biota.

For Central European herbs, ants are one common dispersal vector acting at relatively small spatial scales. Though extensively studied concerning the different benefits to plants, specific dispersal patterns mediated by ants have been reportedly very sparsely and without any validation. Thus, we studied the seed dispersal pattern of a set of myrmecochorous plant species in a novel mesocosm experiment. We examined the seed dispersal distances of four forest herbs (Hollow Root–Corydalis cava (L.) Schweigg. & Körte, Alpine Squill–Scilla bifolia L., and Common Dog-violet–Viola riviniana Rchb. and the annual Ivy-leaved Speedwell–Veronica hederifolia L.) by the red ant Myrmica ruginodis Nylander in 8.25 m² large plots under natural conditions with and without ants. In the presence of Myrmica ants, the bulb geophytes C. cava and S. bifolia showed a significantly higher fraction of dispersed seedlings and a maximum dispersal distance of 322 cm. Estimated by nearest neighbor analyses, distances between single C. cava seedlings were significantly higher in ant plots than in exclosures without ants. The annual species Veronica hederifolia showed a few dispersed seedlings in ant plots only, while the diplochorous hemicryptophyte Viola riviniana germinated in a widely scattered manner with distances up to 241 cm due to ballochorous dispersal in both ant and exclosure plots, but with a maximum of 324 cm only by means of ants. Our results indicate the escape from the mother plant and dispersal for distance as an important benefit for myrmecochorous species, potentially accompanied by benefits through reduced competition.