Human Impacts Pollen Database

Using the Human Impacts Pollen Database:

The morphological key is based on six characteristics: dispersal unit, pollen type, ornamentation, aperture, size class, and shape. A number of thorough discussions of pollen morphology have yielded descriptions of minute differences in pollen morphology (e.g., Erdtman 1969; Kapp 1969; Paldat; Punt et al. 2007). This has led to a proliferation in terms describing, in some cases, similar morphologies. We have tried to simplify the language (while providing alternative terms) to make the key accessible for relatively novice users. We also recognize that pollen grains from a single plant may have slight differences in morphology, such that strict, highly specific categories based on minute distinctions may make keying unknown specimens difficult. More flexible, broader characteristics will allow for variability among pollen grains of a single taxon.

Dispersal unit – whether the pollen is dispersed in single grains (monad), tetrads (4 grains) or polyad (more than 4).

Pollen type – an additional category for two morphologically distinct types of pollen: vesiculate grains (those with bladders) and plicate grains (those with folded exines).

Ornamentation – sculptural elements or modifications to the surface of the pollen grain.

Aperture – based on the shape (round or furrow-like), number of apertures (thinned structural areas) and scars in spores.

Size class – the size of the pollen grain at its maximum diameter: very small (less than 15μm), small (15μm - 25μm), medium (25μm - 50μm), large (50μm - 100μm), and very large (greater than 100μm). Grains measuring near the extreme of a class were placed in adjacent classes. For example, a grain measuring 24μm would be placed in both the small and medium size classes.

Shape – pollen grains are classified by shape or outline. Categories are simplified from discussions of shape based on strict metric data (i.e., the P/E index), but follow that terminology: oblate, prolate, spheroidal, etc.

Taxonomy used in the HIPD follows the International Plant Names Index, and terminology is based on:
Erdtman, G., 1969. Handbook of Palynology—An Introduction to the Study of Pollen Grains and Spores. Munksgaard, Copenhagen.
Kapp, R. 1969. How to Know Pollen and Spores. Wm. C Brown Company: Dubuque. Buchner, R. and M. Weber. 2000 onwards. PalDat - a palynological database: Descriptions, illustrations, identification, and information retrieval. http://www.paldat.org/ Punt, W, PP Hoen, S Blackmore, S Nilsson, and A Le Thomas. Glossary of pollen and spore terminology. Review of Palaeobotany and Palynology 143(2007) 1-81.