Adonis aestivalis -- California

Adonis aestivalis is native to Europe and North Africa along the Mediterranean Basin, Western Asia, and temperate and tropical climates in Asia (Meyer 2015, GBIF). The exact boundaries of its native range are not clearly defined. Adonis aestivalis is on the GRIIS list of Introduced and Invasive Species for the following countries: US, Poland, Czechia, Germany, Croatia, Ukraine, Kyrgyzstan, Bosnia and Herzegovina, and Uzbekistan (GBIF, GRIIS).

Adonis aestivalis is native to Europe and North Africa along the Mediterranean Basin, Western Asia, and temperate and tropical climates in Asia (Meyer 2015, GBIF). The exact boundaries of its native range are not clearly defined. Adonis aestivalis has naturalized in areas with a similar climate to California in Czechia, Germany, Croatia, Kyrgyzstan, Bosnia and Herzegovina, and Uzbekistan (GBIF). Adonis aestivalis has naturalized in the US in areas with a similar climate to California along the northern Appalachians, Washington, Oregon, Northern California, Northern Utah, and Southern Idaho (GBIF, iNaturalist).

Adonis aestivalis has become a weed in the northwestern US in cultivated areas, pastures, and roadsides (ODA 2013). Adonis aestivalis in Oregon is a Class B noxious weed, a weed of economic significance (ODA 2013). Alfalfa and grass hay contaminated by A. aestivalis can be of limited or reduced value as a commodity (ODA 2013). The species is considered invasive in Croatia and Bulgaria (USDA-APHIS). There was no evidence of Adonis aestivalis listed as invasive in Turkey, however this species has caused economic damage there by reducing lentil yields (Erman et al., 2004).

Adonis aestivalis has become a weed in the northwestern US in cultivated areas, pastures, and roadsides (ODA 2013). Adonis aestivalis in Oregon is a Class B noxious weed, a weed of economic significance (ODA 2013). Alfalfa and grass hay contaminated by A. aestivalis can be of limited or reduced value as a commodity (ODA 2013). Croatia and Bulgaria partially match the climate of California, and the species is considered invasive in these countries (USDA-APHIS). There was no evidence of Adonis aestivalis listed as invasive in Turkey (which largely matches California's climate), however, this species has caused economic damage there by reducing lentil yields (Erman et al., 2004).

Adonis microcarpa was declared a noxious weed in areas of Southern Australia in 1956 due to its unpalatability and toxicity, but it is no longer declared a noxious weed (Government of South Australia 2014). There is no evidence that other members of the tribe Adonideae were invasive in a similar climate.

Most occurrences of Adonis aestivalis are within the climate matching California: around the Mediterranean Sea (Portugal, Morocco, Tunisia, Israel, Lebanon, Turkey, Greece, Bulgaria, Albania, Italy, Spain, southern France, Germany, and eastern Belgium), across Asia (Kazakhstan, Uzbekistan, Kyrgzstan, Tajikistian, Afghanistan, Pakistan, Nepal, and southwestern China), and in the US (northern Appalachians, Washington, Oregon, northern California, northern Utah, and southern Idaho).

Adonis aestivalis does occur in cooler climates than those that match California. There are some dense occurrences outside the climate matching California in northern France, western Belgium, and Germany. There are scattered occurrences outside the climate matching California in the UK, Sweden, Finland, Poland, Ukraine, and Russia.

Adonis aestivalis is reported to occur in wildlands, but there are not many accounts of these occurrences, so there is little information on whether Adonis aestivalis displaces native plants. Adonis aestivalis is an herbaceous annual up to 70 cm tall, so as a smaller plant it would have to form stands to displace native plants (Jepson eFlora 2022). There are accounts of Adonis aestivalis forming thicker stands on farmlands, where it can displace crops. This species can form thick stands on roadsides and in irrigated alfalfa (ODA 2013). Adonis aestivalis in untreated lentil fields in Turkey had a density of 30 plants per square meter; however, it was initially overtopped by other weeds (Erman et al 2004). Adonis aestivalis may be capable of forming thick stands in specific cultivated settings, but because there are no accounts of Adonis aestivalis forming thick stands in wildlands, there is not enough evidence to support Adonis aestivalis displacing native plants.

There is no evidence Adonis aestivalis promotes fire or changes fire regimes. Most reports of Adonis aestivalis are in cultivated areas, pastures, and roadsides rather than wildlands (ODA 2013). Adonis aestivalis is an herbaceous annual up to 70 cm tall (Jepson eFlora).

The leaves and flowers of Adonis aestivalis contain the potent cardenolides strophanthin and cymarin (Woods et al 2007). Adonis aestivalis is fatally toxic to several animals including pigs, horses, sheep, and rabbits (Stegelmeier et al 2007; Woods et al 2007). Cattle are less susceptible to Adonis aestivalis toxicity than horses, pigs, and sheep (Woods et al 2007). As little as 450 gms of plant material is fatal to sheep (Woods et al 2007). Adonis aestivalis is known to invade alfalfa fields and contaminate hay, which increases the likelihood of A. aestivalis toxicity affecting livestock.

Adonis aestivalis can be toxic to humans and fish, but problems are less likely to occur considering that Adonis aestivalis is known as a weed of cultivated areas and pastures. Adonis aestivalis contains cardiac glycosides, which can be poisonous to humans, and should only be used medicinally under medical supervision (Maham and Sarrafzadeh-Rezaei 2014). Smaller-sized rainbow trout that were fed a diet containing Adonis aestivalis flowers had mortalities whereas fish on a diet containing Adonis aestivalis pigment extract did not experience mortalities (Kamata et al 1990).

Adonis aestivalis is an herbaceous annual up to 70 cm tall that is unlikely to produce impenetrable thickets (Jepson eFlora). This species can form thick stands on roadsides and in irrigated alfalfa but given its growth habit, it is unlikely to produce impenetrable thickets (ODA 2013).

Adonis aestivalis is a taprooted herbaceous annual that reproduces by seed only (Jepson eFlora, ODA 2013). There is no reported evidence of Adonis aestivalis reproducing or spreading vegetatively.

Adonis aestivalis is an herbaceous annual that reproduces by seed only (ODA 2013). There is no reported evidence of Adonis aestivalis reproducing by detaching fragments, so this could not be a common method of reproduction.

Adonis aestivalis is an herbaceous annual that reproduces by seed only (ODA 2013). I could not locate any studies on the percentage of viable seed for this species. However seeds of A. aestivalis may remain viable in the seedbank for up to 54 years (Wäldchen et al. 2005).

A single plant can produce 114 seeds (Hussain et al., 1993 as cited in USDA-APHIS 2019).

There are no reports of Adonis aestivalis requiring infrequent environmental conditions to germinate. Adonis aestivalis seeds are sold on several sites with no mention of requirements listed for germination (Everly 2022, Outside Pride, PFAF). There is little information on Adonis aestivalis germination rates. When Adonis aestivalis was sown in Hungary in late October, Adonis aestivalis did not germinate at all, but it did germinate in April (Ecseri et al 2015). Seeds of A. aestivalis may remain viable in the seedbank for up to 54 years (Wäldchen et al. 2005).

Adonis aestivalis is an herbaceous annual that reproduces by seed only (Jepson eFlora 2022, ODA 2013).

Adonis aestivalis is reported to flower for three months or less during the summer. Adonis aestivalis flowers in California from May to July (Calflora). Bloom time in Oregon is also mid-summer (ODA 2013).

Adonis aestivalis was introduced to the British Isles in wool though it is unspecified whether wool is the product or on sheep (Clement and Foster 2000 as cited in USDA-APHIS 2019). However, there are no other accounts of this species spreading long distances by animals, so this does not seem to be a frequent occurrence.

There is no evidence that Adonis aestivalis seeds are dispersed long distances by wind or water. Adonis aestivalis seeds are achenes with a terminal recurved or slightly curved beak (Meyer et al 2015). There is anecdotal evidence that the seeds are heavy and don't scatter far (Everly 2022).

Adonis aestivalis has been dispersed through several agricultural means. The species is known as a contaminant of hay (Woods et al. 2007). Adonis aestivalis has been intercepted as a contaminant of grass seed from France and other seeds for propagation from Denmark (AQAS 2019 as cited in USDA-APHIS 2019). Adonis aestivalis was introduced to the British Isles (including the Channel Islands and Ireland) in wool (Clement and Foster 2000 as cited in USDA-APHIS 2019). The Canadian Food Inspection Agency Seed Laboratory has also identified this species in a sample of flower seed mixture from the Netherlands (USDA-APHIS 2019).