Erigeron karvinskianus – September 20th 2026 – Mexican Daisy

Mexican Daisy, inflorescences about 1 cm in diameter, colour white to pale-purple, disk florets bisexual, ray florets female. Flower stalks 4-10 cm. Image: John Grace.

This is a pretty daisy, coming from Central America, cultivated in Britain since 1856 and first recorded as ‘naturalized’ in 1891. It is most common in the southwest of England, but now it has come north and is increasing rapidly in Scotland. Its appearance ‘in the wild’ in Scotland was relatively recent, recorded in 1967 by O.M. Stewart in East Lothian, but now common in Edinburgh and Glasgow. For example, it was first seen in Midlothian (Marchmont, Edinburgh) in 2013 by Jackie Muscott, and now Midlothian has 65 records, many of them in the centre of Edinburgh (e.g. Tron Square, New Calton Burial Ground, Princes Street).

In gravel at Logan Botanic Garden, SW Scotland, September 2026. Image, John Grace.

This plant is admired and loved as a garden plant. Gardeners may enjoy this short movie by Sarah Raven, extolling its virtues. There are several cultivars of Mexican Daisy widely available to growers in the United Kingdom, and the Royal Horticultural Society recommends it especially for rock gardens, coastal gardens, and ‘gravel gardens’. It flourishes in frost-free areas, and so it is often seen at the coast where frosts are fewer and less extreme (although Hind, 2012, suggested it is frost-hardy down to -15 ^oC). Its escape from gardens is inevitable: it has tiny seeds with a pappus of hairs, aiding wind dispersal over considerable distances.

Semi-wild at Logan Botanic Garden, 2021. Image, John Grace.

It belongs to the daisy Family (Asteraceae) and its flowers closely resemble our European native Daisy, Bellis perennis, although the ray florets of Mexican Daisy are often pinkish-purple. Its growth form is however quite different. The flower stalks are longer and quite slender (the child’s daisy-chain would surely not be possible). The stems creep (sometimes rooting) and so it forms distinct patches up to a metre across; it grows taller than Daisy (10-40 cm) by scrambling over itself. Although a perennial, it is short-lived whereas Daisy goes on for many years.

Mexican Daisy, flowering shoot (left) and (right) the launch of a seed (technically, this is an achene, defined as a small single-seeded dry fruit which does not split open to release seed when ripe). Note that achenes in the Asteraceae often have a ‘pappus of hairs’ to aid wind dispersal (think of dandelions).

In some countries it is reckoned to be ‘invasive’. For example Hannah et al. (2019) say: “The invasive species Erigeron karvinskianus or Mexican daisy is considered a significant weed that impacts native forest restoration efforts in New Zealand”. It does have a tap root, but not a big one – it is easily pulled from the soil. From my own local observations, I don’t think it is likely to be classed as ‘invasive’ here in Britain, but one never knows for sure.

Distribution of Mexican Daisy in Britain and Ireland, from BSBI Maps.

Its ecological characteristics (from Henninges et al. 2022) suggest it requires good sunlight, and it can tolerate rather dry conditions. It does not do well on acid soils but it can tolerate soils of extremely low fertility. Mexican Daisy often grows on walls, where all these conditions may occur. One of the best displays of how well it grows on walls and pavings can be seen at the Logan Botanic Gardens where it covered about 50% of the wall area at the end of the garden when I saw it there in 2021. Alas, quite a lot of it has now been removed.

Worldwide records of Mexican Daisy, from GBIF.

In gardens, we often see bees visiting the flowers, and the flowering period lasts from April to October, so it can be offering its nectar to flying insects at times when other flowers are scarce. It isn’t perfumed as far as I can tell (but I haven’t got an insect’s sensitivity to volatiles), but visually the flowers are prominent and they jitter in the slightest breeze, perhaps attracting attention. The only exact information I found about pollination was from California where Frankie et al. (2019) recorded 29 total native bee species, 2 non-native bee species, and 17 total bee genera during their survey. In the Western Himalaya, where it is considered to be invasive, researchers have shown that it benefits the pollination of nearby native plants because it keeps insect pollinators interested in the location for several months (Arya et al. 2025). If not pollinated, Mexican Daisy can still form viable seeds (Hind 2012).

The effectiveness of wind dispersal has often been questioned (Sheldon and Burrows 1973). There are many studies of plants in the Asteraceae attempting to relate dispersal to the size of the pappus and the mass of the achene, often using wind-tunnels. The general conclusion is: for successful launch the flower-head needs to be well above the local boundary layer (i.e. plants need to be tall or on a wall), dry conditions are best (when wet, the hairs become entangled with those of other achenes), and convection currents need to be strong to lift the achenes high above the ground (strong sunlight helps this). Only a tiny fraction of achenes are likely to be dispersed over long distances – most fall on the ground amongst leaf litter around the plant.

Nevertheless, the global distribution of this species is impressive. Note especially the data points from remote oceanic islands. It is possible that these have been transported by humans but more likely they have been carried aloft in the wind.

As for its species name, it is one that I found impossible to pronounce and remember, until I realised it was discovered by a Bavarian by the name of Karvinkski, or to use his full name, Wilhelm Friedrich Frei-herr von Karwinsky von Karwin (1780-1855). He collected many plants from Brazil and Mexico (see Hind 2012). With the name being karvinskianus we should really call it Karwinsky’s Daisy or Karwinsky’s Fleabane.

References

Arya MK, Omanakuttan K and Pandey T (2025). Flower visiting insects of the invasive Mexican daisy (Erigeron karvinskianus, DC) and its proximity effect on native flora in the Western Himalaya. Oriental Insects, 59(2), 340–370.

https://doi.org/10.1080/00305316.2024.2448695

Flora of China 28. Erigeron karvinskianus Candolle, Prodr. 5: 285. 1836.

Frankie G et al. (2019). Native and non-native plants attract diverse bees to urban gardens in California. Journal of Pollination Ecology, 25.

Hannah L, Aguilar G and Blanchon D. (2019). Spatial Distribution of the Mexican Daisy, Erigeron karvinskianus, in New Zealand under Climate Change. Climate. 7(2):24. https://doi.org/10.3390/cli7020024

Henniges MC et al. (2022). A taxonomic, genetic and ecological data resource for the vascular plants of Britain and Ireland. Scientific Data, 9(1), 1.

Hind  N (2012). Erigeron karvinskianus. Curtis’s Botanical Magazine, 29(1), 52-65.

Lunt PH et al. (2025). Biodiversity Performance of Living Wall Systems in Urban Environments: A UK Case Study of Plant Selection and Substrate Effects on Multi-Taxa Communities. Urban Science, 9(12), 519.

Raven, S. current youtube article for gardeners https://www.youtube.com/watch?v=cN_cveFzyn8

Sheldon JC and Burrows FM (1973). The dispersal effectiveness of the achene–pappus units of selected Compositae in steady winds with convection. New Phytologist, 72(3), 665-675.

Sullivan JJ, Timmins SM and Williams PA (2005). Movement of exotic plants into coastal native forests from gardens in northern New Zealand. New Zealand Journal of Ecology, 1-10.

©John Grace