Artemisia (Asteraceae)


Artemisia douglasiana
Photo by John Welch (c) 1996, San Lorenzo River Institute



Austr.NU Pollen Atlas


Artemisia nova
UofAz Palynology

Plant:
(sagebrush [woody] or wormwood [herbaceous])

Pollen light micrograph:
The Artemisia pollen type is routinely distinguished from other pollen produced by members of the sunflower (Asteraceae or Compositae) plant family. Artemisia is a tricolporate, echinate pollen grain recognized by its thick,tapered wall with large collemella, The foot layer and tectum are of uniform thickness, but the layer of thick columellae usually tapers toward the furrows (colpi). The short spines are hard to see with light microscopy, typically they are less prominent than the large collumella in plan view. The spines and rods may interact to produce a reticulate patter in light microscopy.

Pollen scanning electron micrograph (SEM)
The furrow membrane is smooth, and the pore circular. The spines are very short, and widely and evenly placed. In Tranmission Electron Microscopy (TEM) the wall can be seen to be comprised of an outer layer (tectum) T of thin branching collumella overlaying an inner layer of thick collumella C, and a thick foot layer F.

Artemisia vulgaris Artemisia vulgaris

Production and Dispersal:
Production is moderate and dispersal good. Production by woody taxa (sagebrush) seems to be much greater than for herbacious (wormwood) ones.

Preservation:
Preservation of the thick walls is good, and the characteristic shape is easy to recognize in poorly-preserved samples.

Fossil Occurrence:
The earliest plant fossils of Artemisia probably are of mid- Cenozoic age. Artemisia pollen is common in European pollen assemblages from the Dryas Flora (last glacial). It is very aboundant (> 60%) in pollen diagrams from the North American high plains and west during the late glacial.

References:
    Rowley, J.R., Dahl, A.O. and Rowley, J.S. 1981.
    Substructure in exines of Artemisia vulgaris (Asteraceae). Review of Palaeobotany and Palynology 35: 1-38.

Links

Owen K. Davis 12/99