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Pollen Competition and Relatedness in Haplopappus Section Isopappus

Edwin B. Smith
Botanical Gazette
Vol. 129, No. 4 (Dec., 1968), pp. 371-373
Stable URL: http://www.jstor.org/stable/2473105
Page Count: 3
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Pollen Competition and Relatedness in Haplopappus Section Isopappus
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Abstract

Pollen competition phenomena among five taxa in section Isopappus of Haplopappus were studied in an attempt to correlate the phenomena with relatedness. Domestic pollen is prepotent over foreign pollen in all taxa of the section. Such behavior represents a cryptic but effective hybridization barrier. Double pollinations with foreign and then, after a delay, domestic pollen resulted in an increasing percentage of hybrids in the progeny, with increasing delay in application of domestic pollen. The differing pollen types can be matched in fertilizing capacity, as indicated by 50% of hybrids in the progeny, through use of a time handicap. Based on preliminary data, the length of the delay required for equalization of fertilizing capacity is inversely proportional to the degree of relatedness of the taxa.

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