DOI: 10.5061/dryad.6hdr7sr3b
title: Patterns of pollen dispersal and pollen capture in the hybridizing cattails, Typha latifolia and T. angustifolia

description: 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.
description: Pollen dispersal was assessed in a wind tunnel. Inflorescences of
 each of <em>Typha latifolia</em> and <em>T.
 angustifolia</em> were inserted into a wind tunnel and tapped by a
 paddle to release pollen. Pollen was captured downwind on microscope
 slides covered in petroleum jelly at distances of 0.2, 0.4, 0.8, 1.6, 2.0,
 3.0, 4.0, and 5.0 m from the inflorescence and positioned at approximately
 the height of the centre of the pollen source. Dispersal was assessed at
 each of three wind speeds: 1 m/s, 2 m/s, and 5 m/s. We conducted three
 trials for each <em>Typha </em>species at 1 m/s and 5 m/s and
 two trials for each species at 2 m/s. The number of pollen grains (tetrads
 for <em>T. latifolia</em> and monads for <em>T.
 angustifolia</em>) in 1 cm<sup>2</sup> was counted
 manually under a microscope. Data presented are counts of pollen grains
 for each distance x species combination for each trial
 conducted.  Pollen capture of <em>T.
 latifolia</em> and <em>T. angustifolia</em> was assessed
 in each of two cattail stands (sites) near Peterborough, Ontario. At one
 site (Cavan), <em>T. latifolia</em> was the only cattail
 species present, and at the other (Uxbridge), <em>T.
 angustifolia </em>was the only cattail species present. Cattails at
 each site were emasculated before they shed pollen and the female portion
 of the inflorscence bagged to ensure recipient plants did not receive
 pollen from other plants at the sites. One each of two trials days at each
 site, donor cattails (one of each of <em>T. latifolia</em>
 and <em>T. angustifolia</em>) were put in place to act as
 pollen sources for four hours. These donor plants had been collected from
 nearly and put in pots to be left in the middle of the sites to act as
 pollen sources. A subset of female inflorescences were unbagged once the
 donor plants were in place and pollen was left to disperse naturally from
 the donor plants. After four hours, stigmas were removed from the unbagged
 recipient plants and immediately stained and mounted on microscope slides
 using basic fuschin jelly. Pollen grains of each species within 1
 cm<sup>2 </sup>were counted manually under a microscope. These
 counts were scaled by the area of the slide covered by stigmas. Counts
 were converted into proportion of grains being <em>T.
 latifolia</em> for data analysis. 
description: There are two ReadMe files associate with these data files that
 describe what the column headings mean.