Reproductive features of Celmisia species (Asteraceae) in relation to altitude and geographical range in New Zealand

A range of seed and flower characters was examined in 37 species of the New Zealand genus Celmisia (Asteraceae) to determine whether there were any re lationships between reproductive features and the geographic or altitudinal ranges of the species. Using published sources and herbarium material, flo wer attractiveness to pollinators was measured in terms of capitulum size a nd ray/disc length ratio. Dispersibility was measured in terms of seed dry weight, seed terminal velocity, pappus/seed length ratio, and scape/leaf le ngth ratio. Altitude (minimum and maximum) and geographic ranges (number of 1 degrees latitude x 1 degrees longitude squares occupied) were obtained f rom published sources. A multivariate principal components analysis using 1 2 morphological characters revealed the presence of five groups of species differing in capitulum size, seed weight, pappus length, number of pappus b ristles, leaf length and scape length. Linear regressions showed that altit ude was significantly and negatively related to seed dry weight and capitul um size, and positively to scape/leaf length ratio. Geographic range is neg atively related to capitulum size, and positively to ray/disc ratio and alt itudinal range. Amongst the seed features measured, seed weight was the bes t predictor of terminal velocity (an inverse measure of dispersability), bu t lighter seeds also had a higher pappus/seed length ratio. The frequency d istribution of the geographic ranges of the species is highly skewed, with many local species (86% occurring in 15 or fewer one-degree squares) and ve ry few common ones. Two species (C. gracilenta and C. graminifolia) are not ably more common than all the others. A comparison of these species with th e others shows that, on average, they have lighter seeds with more bristles , taller scapes and higher ray/disc ratios, but have smaller capitula. The low geographic abundance of the rare species could not readily be attribute d to any specific reproductive feature, possibly because of the multiple ty pes of rarity represented within the genus. (C) 2001 The Linnean Society of London.