Correlations Among Stigma Depth, Style Length, and Pollen Grain Size: Do They Reflect Function or Phylogeny?

The size and germinability of Scots pine pollen in different temperaturesin vitro

“…However, germinated pollen grains were larger in size than nongerminated. Collectively, these observations infer that early germination and growth of pollen tube may be more dependent on pollen storage materials (Vasil, 1974;Cruden & Lyon, 1985) than pollen size and hydration. Optimum temperature for germination and pollen tube growth varies among species, and the range can sometimes be narrow (e.g.…”

The long-tongued Cretaceous scorpionflyParapolycentropusGrimaldi and Rasnitsyn (Mecoptera: Pseudopolycentropodidae): New Data and Interpretations

“…however, the grains are approximately 2-3 µm in diameter, which is about half the size of the smallest known angiosperm pollen (that of Myosotis spp., or forget-me-not flowers [Proctor et al, 1996]), and too small for high magnification (e.g., 400×) observation, so detailed structure could not be determined. angiosperm and gymnosperm pollen grain size is most commonly in the 30-40 µm size (Cruden and lyon, 1985;Proctor et al, 1996;Kirk, 1993). The small plume of grains in the amber adjacent to the scorpionfly apparently came from the insect, since the grains are denser near the insect and many grains are still attached to fine setae on the abdomen.…”

Pollen morphology in the genus Veronica L. (Plantaginaceae) and its systematic significance

“…In contrast, a positive relationship between pollen grain size and stigma depth (distance from the external surface of the stigma to the transmission tissue in the style, which reflects the distance that a pollen tube has to grow to reach the resources in the style) has been reported (Cruden & Lyon, 1985;Cruden, 2000). There is also considerable evidence supporting the fact that there are types of resources (i.e., starch) in the style and transmission tissue, which do not occur in the stigma and that are used by growing pollen tubes (Cruden, 2000, and examples cited therein).…”

“…It is interesting to note, however, that where positive correlations have been observed between pollen size, style length and stigma depth in closely related species of Polygonum, it has been suggested that it might reflect a phyletic, rather than a functional, relationship (Cruden & Lyon, 1985) and this could also be the case in Veronica.…”

“…The lack of a correlation between pollen volume and style length in comparisons of both related and unrelated plants has been shown for several plant species (Cruden & Lyon, 1985), however, it would seem to be inconsistent with the hypothesis that pollen grains must contain sufficient resources to sustain the growth of a pollen tube to an ovule (Cruden & Lyon, 1985). In contrast, a positive relationship between pollen grain size and stigma depth (distance from the external surface of the stigma to the transmission tissue in the style, which reflects the distance that a pollen tube has to grow to reach the resources in the style) has been reported (Cruden & Lyon, 1985;Cruden, 2000).…”