Patterns of pollen dispersal and pollen capture in the hybridizing cattails, Typha latifolia and T. angustifolia

Pollen dispersal regulates the formation of the invasive, wind-pollinated
hybrid cattail T. × glauca, the F1 offspring of the broadleaf (T.
latifolia) and narrowleaf (T. angustifolia cattail. An earlier study
suggested that pollen dispersal by T. latifolia might be spatially
restricted, with most dispersal occurring over distances less than 2 m.
Restricted pollen dispersal would imply that hybrid formation primarily
occurs within mixed stands of cattails. Hybrid formation might also be
affected by preferential receipt of conspecific pollen, but this has not
been investigated for cattails. We compared patterns of pollen dispersal
for T. latifolia and T. angustifolia using a wind tunnel. We then tested
whether patterns of pollen receipt were biased toward the capture of
conspecific versus heterospecific pollen using monospecific cattail stands
with a single local pollen source. Results from the wind tunnel partially
supported the previous finding of spatially restricted pollen dispersal
for T. latifolia, the paternal parent of F1 hybrids. Pollen receipt by T.
angustifolia was biased toward the capture of conspecific pollen.
Localized pollen dispersal by T. latifolia and preferential conspecific
pollen capture by T. angustifolia should reduce rates of hybrid formation
below that expected under random mating.