Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Abstract

.: Pollen morphology of Polemoniaceae in relation to systematics and pollination systems: Scanning electron microscopy. Grana. Vol. 15, pp. 91-112, 1975. Uppsala 1976. ISSN 0017-3 134. Representative pollen grains of each genus and section of the family Polemoniaceae were examined with scanning electron microscopy. Exine pattern diversi ty within the family is di scussed in relation to pollination biology. Pollen data su pport some previously recognized rel ation ships within the fa mily; in other instances the use of polle n morphology suggests the institution of new associa tions. The value of pollen morphology as an index to possible phylogenetic interpretations within th e Polemoniaceae is discussed.

Comparative pollen structure and pollination biology in theCallitrichaceae

“…Although the functional association of pollen morphology and ultrastructure to particular pollination syndromes is not always related (e.g., Taylor and Levin, 1975) nor well-understood, a number of angiosperm families have in fact Lccn shown to demonstrate positive correlations between these palynological characters and thc;r pollination systems (e.g., Osborn, Taylor, and Schneider, 1991). This is especially true for hydrophilous species in which reduction of exine thickness cr lack of an exine altogether charactl'rizes the pollen (e.g., Cox, 1988;Philbrick, 1988).…”

Pollen morphology ofAsphodelusL. (Asphodelaceae): taxonomic and phylogenetic inferences at the infrageneric level

“…Indeed a change from allogamy in A. ayardii to autogamy in A. teriiiifbliiis occurs (Diaz Lifante & Valdis 1995). In this context, Muller (1979), Taylor & Levin (1975) and Takhtajan (1991) associate the decrease in pollen size of closely related species with a shortening of style, a reduction of pollinator size and a decrease of pollen/ovule ratio. Walker & Doyle (1975) suggest that the most primitive angiospermous pollen type is monoanasulcate and bilateral, with tectate-imporforate and psilate exine.…”

A Phylogenetic Classification of Polemoniaceae

“…Classifications frequently function, for better or for worse, as proxies for phylogeny in comparative studies (e.g., Taylor and Levin 1975;Rickleffs and Renner 1994). The inferential accuracy achieved in such studies depends upon how well the classification accurately reflects phylogeny.…”

“…Nuclear and chloroplast gene sequences also support the monophyly of Phlocideae (Johnson et al 1996;Porter 1996 Affinities of Gymnosteris lie with PhLox and Microsteris (Johnson et al 1996) rather than CoLLomia (W herr y 1944; Grant 1959Grant , 1998a. Gymnosteris pollen is nearly identical to that of PhLox (Stuchlik 1967a ;Taylor and Levin 1975), and seeds produce copious mucilage when wetted that appears to be truly mucilaginous in origin (as does Microsteris), rather than the expansion of obvious spiricles as observed in CoLLomia (Schnopf and Deichgraber 1983). Also, the congested inflorescence of Gymnoster is, although similar to those found in Collomia, is equally similar to those found in PhLox and elsewhere in PhJocideae.…”

“…This classification has served as the framework for sampling in comparative and evolutionary studies for forty years (Table 1). A number of broad comparative surveys, conducted in Polemoniaceae during this interval (e. g., Stuchlik 1967a, b; Taylor and Levin 1975;Harborne and Smith 1978;Smith et al 1982;Wilken et al 1982;Plitmann andLevin 1983, 1990;Carlquist et al 1984;Steele and Vilgalys 1994;Johnson et al 1996 ;Porter 1996), were interpreted in the framework of Grant's classification. As a result, some workers suggested a revised taxonomy may better reflect the accumulating evidence of character distributions supporting alternative views of phylogenetic relationship (e.g., Smith et al 1977;Day and Moran 1986;Johnson et al 1996;Porter 1996).…”