Adonis aestivalis aka Summer Pheasant's Eye

Adonis aestivalis is known as summer adonis or pheasant's eye. It belongs to the buttercup family, Ranunculaceae. Its native range runs from Europe to western Nepal. It grows in temperate regions, including fields with lime-rich soil. This plant is an annual, though NC State reports some perennial growth. Gardeners brought it to the United States as an ornamental. It later escaped into pastures and along roadsides. NC State reports invasive growth in the western United States.

The plant grows upright from a taproot and grows fast. RHS gives a garden height of up to 1.6 feet [0.5 metres]. Its description places most plants below 1.3 feet [0.4 metres]. NC State reports heights reaching 2 feet [0.61 metres]. Plants spread about 0.5–1 foot [0.15–0.3 metres] in that account. RHS allows a spread of 1.6 feet [0.5 metres]. The light green stems have grooves and few branches. Alternate leaves divide two or three times into narrow segments. Their fine green growth has a soft, fern-like look.

Single, cup-shaped flowers appear from May to July. Chicago Botanic Garden lists a shorter season of May to June. RHS describes red summer flowers. NC State also records purple-red, orange and yellow blooms. The waxy petals surround dark purple-black anthers. Bees, flies and beetles pollinate the flowers. The plant also attracts butterflies. After flowering, green achenes form in upright, narrow clusters. Each cluster holds about 10–15 of these small fruits. A plant may produce more than 100 seeds.

Grow summer adonis in sun or partial shade. It needs moist soil that drains well, preferably alkaline. Sources list sand, loam, chalk and clay among suitable soils. Choose a sheltered place, as wind may make small plants need support. RHS rates it H4; Chicago lists USDA zones 3–9. It suits borders, rock gardens and planting beneath deciduous shrubs. Sow fresh seed in summer in a cold frame. Seeds may sprout soon after falling or wait until spring. The plant needs no pruning.

RHS reports few usual pest or disease problems. NC State warns of aphids and damage from slugs. All parts are poisonous when eaten, despite a low toxicity rating. Reported symptoms include nausea and vomiting. Livestock, including horses, can also suffer poisoning. No edible uses are recorded. Traditional medicinal uses include heart remedies, diuretics and laxatives. These uses do not make the plant safe to consume.