Figure 2.

Pollen from the 12 species of grass investigated here clustered into four groups at 95% accuracy using features ι and ν. Thumbnails show the surface ornamentation of species within each group. Group one (red open circles) contains five species: A. odoratum (1), Phalaris arundinacea (3), Poa australis (4), Triodia basedowii (9) and Bothriochloa intermedia (10). Group two (blue solid triangles) contains three species: Dactylis glomerata (2), Sporobolus pyramidalis (8) and O. hirtellus (12). Group three (black plus signs) contains three species: Cynodon dactylon (6), Eragrostis mexicana (7) and Digitaria insularis (11). The two outliers are specimens 13 and 20 of E. mexicana. Group four (green open squares) contains a single species: S. tenuifolia (5). Images taken using SEM and shown at ×12 000 magnification. Scale bar measures 120 pixels and represents 1 µm. In these images, 1 pixel measures 8.(3) nm. Numeric species codes from table 1.