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Telopea Vol. 6(4): 1996 
both morphs are highly self-compatible as well as cross-compatible, but thrum plants 
exhibit high levels of autogamy (Omduff unpublished; see following discussion). Thus, 
in Australian species of Villarsia, at least three different breeding systems are associated 
with distyly: a more or less conventional one as well as two breeding systems combining 
unexpected mixtures of incompatibility and compatibility relationships of the two 
morphs. Although deviations from conventional distyly are known in other families, 
the combinations of compatibility and incompatibility associated with distyly in four 
species of Villarsia are unknown outside the genus (Ganders 1979a; Casper 1992; 
Dulberger 1992; Lloyd and Webb 1992). The nature of the breeding system in a Villarsia 
species thus cannot be inferred merely by the presence of distylous flowers. 
This paper describes the breeding system of Villarsia exaltata (Solander ex Sims) G. Don, 
a robust, perennial, aquatic or wetland hexaploid species ranging from coastal southern 
Queensland (the Gympie region) through coastal New South Wales to central coastal 
Victoria (Cranbourne), with outlying populations in northeastern Tasmania (Aston 
1969). Tire species has distylous flowers (illustrated by Aston, 1969, Fig. 27). Stigmas of 
pin flowers are exserted well beyond the mouth of the corolla and stigmas of thrum 
flowers are positioned at or below the mouth of the corolla (Aston 1969, Fig. 27). 
Anthers of each floral form occupy positions approximately equivalent to positions 
occupied by the stigmas of the other form. Pin stigmas are lanceolate and densely 
covered with papillae on the inner face and all but the median portion of the outer face, 
whereas thrum stigmas are more or less deltoid with papillae uniformly covering both 
the outer and inner faces (Aston 1969, Fig. 27; Dulberger and Omduff unpublished.). 
Villarsia exaltata is the only one of the three eastern Australian Villarsia species that 
has distylous flowers; the flowers of V. reniformis R. Br. and V. umhricola Aston are 
not heterostylous. These three eastern Australian species are hexaploid with n = 27 
(V. exaltata, V. iimbricola) or hexaploid with rare tetraploid populations (V. reniformis-, 
Omduff 1974). The distylous Western Australian Villarsia species are diploid, although 
tetraploid races occur in one of them (Omduff 1974; Omduff and Chuang 1988). 
This paper presents the results of an artificial pollination program carried out on 
cultivated plants of V. exaltata, a program designed to identify the presence and 
nature of the incompatibility system, if any, that is associated with the pronounced 
floral dimorphism of this species. 
Materials and methods 
Seeds of Villarsia exaltata were obtained from a population native to the grounds of the 
North Coast Regional Botanical Garden at Goffs Harbour, New South Wales, in the 
mid-1980s. Plants were grown to maturity in the greenhouses of the Department of 
Botany, University of California at Berkeley and upon flowering were assigned 
identifying codes indicating the morph and a plant number. A second collection of 
seeds obtained by J. A. West at Wilsons Promontory, Victoria, in 1991 contained a 
mixture of seeds of V. exaltata and V. reniformis that were growing sympatrically. This 
collection produced only a few thmm plants of V. exaltata, plants of V. reniformis, and 
several hybrids between the two species. In order to eliminate the possibility of dioecy 
in V. exaltata, pollen viabilities were estimated for five pin and four thmm plants of 
the Goffs Harbour progeny by mounting pollen grains in aniline blue-lactophenol on 
a glass slide and scoring stained grains in a minimum sample of 100 pollen grains. 
Pollen size was measured using a sample of 10 pollen grains from each of three plants 
of the two morphs in the Goffs Harbour progeny with an ocular micrometer. 
Six pin plants and four thrum plants of the Goffs Harbour progeny and four thrum 
plants of the Wilsons Promontory progeny were used in a pollination program 
