Plesiomorphic and apomorphic pollen structure characteristics of anthemideae (Asteroideae: Asteraceae)

Abstract

Anthemideae (Asteroideae: Asteraceae) pollen grains have basal columellae, a structural type called “anthemoid” in earlier publications. To survey structure variation in Anthemideae pollen, we examined freeze‐sectioned grains from 45 species within 23 representative genera using scanning electron microscopy (SEM). From resulting data and a literature review, we concluded that: 1) pollen of Anthemideae taxa is qualitatively identical except for Ursinia (grains essentially lack basal columellae) and the Artemisia group (branches of basal columellae are complex and interwoven); 2) the double tectum (a term introduced in this study) is a synapomorphy of Asteroideae and plesiomorphic in Anthemideae; 3) apomorphies of Anthemideae grains include large basal columellae, a thick foot layer, and absence of internal foramina; and 4) Anthemideae pollen is qualitatively different from similar pollen in Lactucoideae, a distinction we recognized by restricting “anthemoid” to Anthemideae grains. Ursinia grains have occasional basal columellae and features resembling rolled‐up columellae; we consider these vestiges of a reversal to the plesiomorphic condition. To assess quantitative structural variation, 2,200 image‐analysis measurements were taken from 73 SEM micrographs. Intrageneric variation was analyzed by standard deviation, and intergeneric variation by principal components analysis. Compared to other Anthemideae taxa, the structural elements of Artemisia grains have reduced dimensions and variability. Otherwise, structural radiation of Anthemideae pollen has produced a phenetic continuum.

Compositae

“…The lactucoid type exhibits one or more of the following features (Vezey et al 1994): branched infratectal columellae (e.g. The lactucoid type exhibits one or more of the following features (Vezey et al 1994): branched infratectal columellae (e.g.…”

Molecular Phylogeny and Biogeography of Tribe Anthemideae (Asteraceae), Based on Chloroplast Gene ndhF

“…Otherwise, placement of genera within Anthemideae remains relatively unchanged from historical taxonomic treatments (Bremer and Humphries, 1993). The tribe is characterized by the possession of dissected leaves (sometimes entire), a paleaceous pappus (sometimes absent), ecaudate or short-tailed anther appendages, truncate penicillate style branches with two parallel stigmatic lines, anthemoid pollen Vezey et al, 1994), and an aromatic nature resulting from high concentrations of monoterpenes and sesquiterpenes (Greger, 1977;Heywood and Humphries, 1977;Bremer and Humphries, 1993;Bremer, 1994).…”

Pollen morphology of endemic species of theGonospermumLess.,LugoaDC. andTanacetumL. complex (Asteraceae: Anthemideae) in the Canary Islands (Spain), and its taxonomical implications

“…Oberprieler et al (2006Oberprieler et al ( , 2007, based also on nrDNA ITS sequence variation (Oberprieler, 2005), suggested an inclusion of Gonospermum and Lugoa in the genus Tanacetum. There are numerous publications on pollen morphology of the genus Tanacetum (Diez, 1987;Pla Dalmau, 1961;Reille, 1992Reille, , 1995Reille, , 1998Tormo & Ubera, 1987Skvarla & Larson, 1965;Skvarla & Turner, 1966;Vezey et al, 1994;Wodehouse, 1935), but only little published information for the Canary Island endemic species. We know of no such studies on Lugoa pollen.…”

“…In the case of Gonospermum there are only two studies. One study by Vezey et al (1994) analysed pollen of two specimens in the Anthemideae from the herbarium in Montpellier (MPU), and one study by Reille (1998) included a light microscope photograph of a pollen grain of Gonospermum fruticosum. The present study was therefore initiated to analyse pollen morphology in this group of plants and to investigate the role of pollen morphology in clarifying the controversial taxonomy of these taxa.…”