Yarrow (Achillea millefolium) is a widespread perennial valued for its hardy nature and distinctive, flat-topped flower clusters. Identifying this plant in a garden or lawn requires recognizing its earliest form, the seedling. This initial stage looks quite different from the mature, feathery foliage, making accurate identification challenging. Learning the specific characteristics of the tiny yarrow seedling is important for distinguishing it from common garden weeds.
Key Identifying Features of Yarrow Seedlings
Germination begins with the appearance of the cotyledons. Yarrow cotyledons are small, typically oblong to egg-shaped, measuring about 1/8 to 1/6 of an inch long. These first leaves have smooth margins and bear little resemblance to the deeply divided foliage of the mature plant. They provide energy for the seedling until the true leaves develop.
The transition to the first true leaves marks the beginning of the plant’s recognizable form. These true leaves emerge alternately along the stem and immediately show the deeply lobed structure defining the species. Each true leaf is sharply pointed and deeply cut into linear segments. This structure provides an early indication of the mature plant’s fine, fern-like texture, which is a significant clue for identification.
As the seedling matures, it develops into a small rosette, with true leaves often less than an inch in size. The leaves and stems have many small, soft hairs that mostly lie flat against the surface. This fine hairiness contributes to a slightly fuzzy appearance and texture. The highly dissected nature of the young foliage explains the common name, millefolium (thousand leaves), even at this early stage.
Differentiation: Yarrow Seedlings vs. Common Look-Alikes
Distinguishing yarrow from similarly textured seedlings is necessary to avoid mistakenly removing a desirable plant. Common look-alikes include wild carrot (Daucus carota) and Mayweed chamomile (Anthemis cotula). While all three present finely cut foliage, differentiation relies on careful examination of hair patterns and smell.
Wild carrot seedlings also form a rosette of finely dissected leaves. However, yarrow rosette leaves have hairs pressed flat against the surface, while wild carrot leaves are either hairless or feature short, bristly hairs. Additionally, crushing the foliage of wild carrot releases a strong, recognizable carrot scent, a feature absent in yarrow.
Mayweed chamomile seedlings exhibit much less hairiness than yarrow. A more dangerous confusion can occur with young poison hemlock (Conium maculatum), which is highly toxic. Poison hemlock has a distinct, foul odor when crushed. Yarrow foliage, by contrast, has a fresh, slightly soapy, and pleasant fragrance when rubbed, serving as a reliable, non-visual identifier.
Growing Context: Where and When Seedlings Emerge
Understanding the environmental context provides supplementary evidence for identification. Yarrow seedlings thrive in full sun and well-drained soil. The species is tolerant of poor, dry soil, often colonizing disturbed areas where other plants struggle. This preference for drier locations helps rule out seedlings that favor consistently moist environments.
Seeds can be sown from early spring through early summer, or in the fall for germination the following season. When conditions are favorable, particularly with soil temperatures around 18–22°C, germination typically occurs within 10 to 14 days. The appearance of seedlings in areas matching these specific growing conditions and timing strongly suggests the presence of yarrow.