More amazing forget-me-not pollen!

Te Papa Botany Curator Heidi Meudt has published a new comprehensive study on the pollen of southern hemisphere forget-me-nots (Myosotis, Boraginaceae).

The new study is the third and final publication detailing the morphology of forget-me-not pollen using scanning electron microscopy (SEM). The first two studies, published in 2016 and 2020, covered about half of the southern hemisphere species. This study, published in 2026 in the New Zealand Journal of Botany, sampled the remaining 31 species to complete the pollen survey.

Gathering and analysing the pollen data

In this study, Heidi was granted permission to take pollen from botanical specimens from Te Papa’s herbarium, the Allan Herbarium in Lincoln, the Otago Regional Herbarium in Dunedin, and the Auckland Museum herbarium. Samples were sent to the Manawatū Microscopy and Imaging Centre at Massey University for preparation and imaging on the SEM.

Heidi used specialised software to make measurements and observations of the tiny pollen grains in the SEM images. She then analysed the new data with the previously published data using ordination and clustering statistical methods to visualise morphological patterns among all southern hemisphere species of Myosotis.

Pollen from nearly all species was included

The first main outcome of the study was that now, nearly all southern hemisphere species of Myosotis have now been surveyed, imaged and analysed. Only two species were unable to be included as their pollen grains were lacking in quality or quantity and could not be imaged.

Check out some of the new pollen images in the following slideshow.

New pollen variation found

Another important result is that additional morphological variation was found – including one new pollen type. Although they can be difficult to categorise and can have intermediate forms, pollen types are nevertheless useful categories for grouping and comparing pollen.

Until the current study, most southern hemisphere Myosotis pollen could fit into one of five different pollen types, but five species studied here had larger pollen with a high P:E ratio (essentially the ration of length to width). And “larger pollen” means 18-22 microns long instead of 10-17 microns long – which is still very small! Hence, a new pollen type was born – M. brockiei type – found in species M. arnoldii, M. brockiei subsp. brockiei, M. brockiei subsp. dysis, M. capitata, and M. concinna.

Looking at the bigger pollen picture

Although most species sampled multiple times usually were found to have just one pollen type, some species have multiple types. This intraspecific variation may be due to different factors, including that Myosotis species have undergone speciation only recently in geological history, or are still in the process of doing so!

The findings were also interpreted in the bigger picture by comparing them to evolutionary trends in published papers on the genus Myosotis, tribe Myosotideae, subfamily Cynoglossoideae, and family Boraginaceae.

The importance of research collections like Te Papa’s herbarium

Finally, this study highlights the importance of botanical research collections for scientific research. Palynology – the study of pollen – is one of many fields of research that relies on herbarium specimens from natural history collections. For this and many other reasons, we need to make sure these collections are valued, cared for, resourced, and accessible, now and centuries into the future.

Pollen grains from the 2026 study – and from all three studies – can be seen on Te Papa’s Collections Online.

Acknowledgements

Thanks to Te Papa Collection Manager Botany Bridget Hatton, Kat Whitney and Hazel Loughrey from the Te Papa Collection Access team, staff at the Manawatū Microscopy and Imaging Centre (especially Raoul Solomon, Yanyu He, Niki Minards, and Matthew Savoian), and staff at AK, CHR and OTA herbaria for their support of this study.

References

• Meudt HM. 2026. Ordination and Model-Based Clustering Analyses Highlight Palynological Variation and Patterns in a Comprehensive Pollen Survey of Southern Hemisphere Forget-Me-Nots (Myosotis, Boraginaceae) New Zealand Journal of Botany 64: e70087 (1-19).
• Meudt HM, Thorsen MJ, Prebble JM. 2020. Taxonomic revision of the Myosotis australis group (Boraginaceae) in Australia, New Zealand and New Guinea. Australian Systematic Botany 33:477-524.
• Meudt HM. 2016. Pollen morphology and its taxonomic utility in the Southern Hemisphere bracteate-prostrate forget-me-nots (Myosotis, Boraginaceae). New Zealand Journal of Botany 54(4): 475–497.