The research by Panchen and colleagues used herbarium records of 97 species from the past 120 years. Digitisation of herbarium material allowed the team to examine 17,000 individual specimens, tagged with a date and place of collection to see how plants responded to climate.

A close-up view of bright yellow Arctic poppy flowers (Papaver species) blooming in a harsh, rocky Arctic landscape. Several large, papery yellow petals form cup-shaped flowers on short stems, growing among scattered gray stones and sparse vegetation. In the background, stone cairn stands against a dramatic cloudy sky, with barren hills and Arctic tundra extending to the horizon.
Papaver radicatum ssp. radicatum in Iceland. Image: carnifex / iNaturalist. CC-BY.

Tracking Arctic systems is difficult, but important as the region is warming 3× faster than the global average. Would more heat allow plants to grow for longer? To see if this was happening, the team examined the digitised records of herbaria to see what the plants actually did. The botanists examined the specimens, using high-resolution images. Each specimen was scored for flowering stage. Using herbaria meant the team had effective access to all the Canadian tundra, and comparisons over many decades for plants. The results are worrying.

A map of northern Canada with purple spots marking the location of specimens. The spots are clustered on the northern shores of Yukon and the Northwest Territories, and across the mainland and islands of Nunavut.
Spatial distribution of herbarium specimens in flower collected north of the treeline across the Canadian Arctic and accessioned in the National Herbarium of Canada (CAN). Panchen et al 2025.

Warmer temperatures mean plants flower earlier. The plants flowering early in the season advanced by around a day. BUT warming is greatest later in the season. This causes plants flowering later in the season to advance flowering by a lot more, so overall the flowering season shortens.

A detailed close-up of large-flowered wintergreen (Pyrola grandiflora) showing its distinctive drooping, bell-shaped white flowers tinged with pink along a tall reddish stem. The waxy, nodding flowers hang from the stem like small lanterns, with visible stamens and pistils inside. At the base, glossy dark green oval leaves form a rosette pattern typical of wintergreen plants. The background shows blurred Arctic tundra vegetation and rocky terrain under a pale sky. This species was noted in the research as having the highest temperature sensitivity, responding to warming by advancing flowering time by 2.71 days per degree Celsius.
Pyrola grandiflora in Greenland. Image: ingvildriska / iNaturalist. CC-BY.

The changes in plants have effects on insects. While nectar is available sooner, the much earlier flowering for late season plants means flowering is over a lot sooner. A shorter flowering season means less time for insects to gather nectar and pollen.

The shorter season compresses competition for insect pollinators, which will affect plant reproduction. At the other end of the food web, the things that eat insects, like birds and rodents, will also have a reduced feeding period, as the effects of changes cascade through the ecosystem. Panchen et al write: “Convergence of flowering times of later- and earlier-flowering species could alter the competitive dynamics in tundra plant communities, possibly leading to changes in plant community composition and species abundance.”

A dwarf hawksbeard (Crepis nana) plant displaying a cluster of bright yellow, dandelion-like flowers at its center, surrounded by a distinctive rosette of thick, spatula-shaped green leaves. The low-growing plant forms a compact cushion against gray gravelly soil, demonstrating the typical growth form of Arctic plants that hug the ground to conserve heat and resist harsh winds. This species showed the most dramatic response to climate change in the research, advancing its flowering time by 3.85 days per decade earlier since 1915.
Crepis nana / Askellia pygmaea in Alaska. Image: abcdefgewing / iNaturalist. CC-BY.

This also suggests that some plants may become conservation priorities. Plants that are less able to adjust their flowering times may find that warmer temperatures put them out of sync with insect partners, or else vulnerable to other problems while trying to grow seeds in the rising heat. The problem is not simply that the changes are happening quickly, the change is also accelerating, so this paper is a warning that close monitoring is vital. Changes in the north can reach a long way south.

READ THE ARTICLE

Panchen, Z.A., et al. (2025) “Digitised herbarium specimen data reveal a climate change-related trend to an earlier, shorter Canadian Arctic flowering season, and phylogenetic signal in Arctic flowering times,” New Phytologist. Available at: https://doi.org/pwnc (FREE)

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Cover image. Saxifraga oppositifolia in Switzerland by cortina/ Naturalist. CC-BY.