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Abstracts, XIV OPTIMA Meeting, Palermo (Italy) , 9-15

Abstracts, XIV OPTIMA Meeting, Palermo (Italy) , 9-15

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<strong>XIV</strong> <strong>OPTIMA</strong> <strong>Meeting</strong>, <strong>Palermo</strong> (<strong>Italy</strong>), 9-<strong>15</strong> September 2013<br />

Morphometric and reproductive variation in the strict endemic Helichrysum<br />

melitense (Asteraceae) in Gozo, Malta<br />

XIBERRAS J., LANFRANCO S.<br />

Department of Biology, University of Malta, Msida, Malta. E-mail: sandro.lanfranco@um.edu.mt<br />

The aim of this study was to characterise the distribution, leaf-morphological amplitude and reproductive<br />

effort of the strict island endemic Helichrysum melitense (Pignatti) Brullo, Lanfranco, Pavone<br />

& Ronsisvalle (Asteraceae) in Gozo, Malta.<br />

This species is restricted to the coastal fringe of Western Gozo and was rarely observed further<br />

inland. Five main sub-populations, those at Ponta tal-Wardija, Tal-Port, Fuq il-Qawra, Ta’ Slima and at<br />

Il-Ponta ta’ Hekka, were recorded and surveyed. A total of 983 plants were investigated. The largest<br />

sub-population was that at Tal-Port (364 individuals) whilst the smallest was the one at Il-Ponta ta’<br />

Hekka (30 individuals).<br />

The plant has very low fertility. Out of 4877 flowers that were dissected, 2836 had not set seed,<br />

and only a small proportion (7.23%) of the seeds that formed were found to be potentially viable.<br />

Despite the low seed production, the overall population size has not been observed to diminish over<br />

the past thirty years, suggesting that this low reproductive rate may nonetheless represent replacement<br />

level for the species.<br />

Variation in leaf morphometry (leaf length, leaf width and leaf area) was investigated across the five<br />

main sub-populations. The sub-population at Il-Ponta tal-Wardija and Ta’ Slima had long and narrow<br />

leaves, those at Fuq il-Qawra and Tal-Port had short and narrow leaves while the smallest sub-population<br />

at Il-Ponta ta’ Hekka had very long and broad leaves. Variations in leaf morphometry within and<br />

across sub-populations showed low, non-significant correlation with environmental factors and thus<br />

were attributed to intrapopulation variation.<br />

Comparison of leaf morphometry between H. melitense and Helichrysum rupestre, (within which the<br />

Gozo populations were originally placed by Pignatti) showed a statistically-significant difference on<br />

the basis of leaf width. This does not confirm whether H. melitense is a distinct species or not, as leaf<br />

morphometry is highly variable across the genus Helichrysum.<br />

<strong>15</strong>5

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