Pollination and Wind Dispersal of Pollen in Arceuthobium

Abstract

The mode of pollination was studied in 2 dwarf mistletoes, Arceuthobium douglasii and A. strictum, from Utah and northern Mexico. Insect visitations to the staminate flowers of A. strictum were common. Visits were found to be rare, however, to the pistillate flowers and to either sex of A. douglasii. Pollen was found to be consistently liberated by the wind from the well—exposed anthers. Air—borne pollen concentration decreased rapidly with distance from the source. No inferences, however, could be made from the data as to dispersal distance. The paucity of insect visitations, the abundance of air—borne pollen, and the moderate to high seed set combined with the absence of apomixis (in A. douglasii) were considered evidence for an anemophilous pollination syndrome. The genus as a whole appears to be anemophilous based on the uniformity of the reproductive morphology. The floral characteristics of Arceuthobium were reevaluated with respect to their suggested role in wind pollination.

Pollen clumping and wind dispersal in an invasive angiosperm

“…Large clumps of pollen like those observed during pollen shedding were rarely observed in pollen samples collected above the canopy, indicating that clump breakdown occurs relatively quickly. Our hypothesis of turbulent disaggregation of pollen clumps explains observations by Player (1979) and Lisci et al (1996) that pollen clump size tended to be inversely proportional to mean wind velocity; higher wind velocities generate more turbulence in environmental flows, which would more quickly and thoroughly disaggregate pollen clumps. It should be noted that previous researchers describe for the initially released pollen clumps a period of adherence to surrounding vegetation before eventual entrainment into the lower atmosphere (Bianchi et al, 1959).…”

Pollination and mating systems of Apodanthaceae and the distribution of reproductive traits in parasitic angiosperms

“…With the exception of the Viscaceae genus Arceuthobium , in which nectar‐offering and fly‐pollinated species may sometimes receive wind‐carried conspecific pollen (Player, 1979), parasitic species are animal‐pollinated, with all pollinator categories from vertebrates to insects represented (Table 1). Figure 4 shows some of the pollination syndromes represented (Fig.…”

Equations for the Motion of Airborne Pollen Grains Near the Ovulate Organs of Wind‐pollinated Plants

“…Biological assumptions concerning the role of size, shape and density used in the model are also justifiable (see Whitehead, 1969;Harrington, 1979;Player, 1979). The behavior of airborne biological structures (spores, pollen, seeds, fruits) will vary depending upon such factors as the speed of descent, the height of release, wind speed/turbulence and morphological adaptations for dispersal (Gregory, Longhurst, and Sneeramula, 1961;Sneeramula and Ramalingam, 1961;Csanady, 1963;Watkinson, 1978;Chamberlain, 1975;Tonsor, 1985;Augspurger and Franson, 1987).…”

“…Empirically, it has also been shown that some plants may be able to preferentially capture conspecific pollen grains. Although preferential pollen capture may be the exclusive result of the morphology ofovulate organs, there are a number ofreasons for inferring that the physical properties ofpollen grains play an equally important role: the density and size of an object will determine in part the extent to which the object settles out of a transport medium (Dyakowska and zycki, 1959;Harrington, 1979;Player, 1979). Thus, the shape, size, and density of pollen grains may vary intra-and interspecifically.…”