Achillea erba-rotta, common name simple leaved milfoil, is a perennial flowering plant of the genus Achillea, belonging to the sunflower family.[2]
Description
Achillea erba-rotta is a polymorphic species, as its physical characteristics clearly vary depending on the variety. The biological form is chamaephytesuffruticose,[3] as these plants have perennating buds borne close to the ground and are woody in the lower part of the stem, with herbaceous yearly branches. The primary root is a rhizome.
This plant reaches on average 12–18 centimetres (4+3⁄4–7 in) in height.[3] The stems are woody and creeping, almost glabrous or with short hair and with erect flowering branches. The leaves of sterile branches are lanceolate-spatulate, 5–7 millimetres (3⁄16–1⁄4 in) wide and 26–30 mm (1–1+1⁄8 in) long, with 4–7 teeth on each side.[3] Cauline leaves are alternate, sessile, toothed and progressively linear, about 2–3 mm (1⁄16–1⁄8 in) wide and 11–22 mm (7⁄16–7⁄8 in) long.[3] Appearing from July to August, the flowers are hermaphroditic and pentamerous, arranged in corymbs with many heads, about 3 mm in diameter, with rounded ligules.[3] The fruit is a flattened achene with no pappus.
