Yarrows
What are they?
The yarrows and their relatives are members of the large, Asteraceace family, but are rather different to most members of that family. However, close study of the flowers will reveal the family relationship, as the flowerheads consist of many, small, tubular flowers, the inner ones in the head bearing tiny petals, while the outer flowers have larger petals, arranged in a circle around the outside of the cluster.
Where are they found?
The European Yarrow is a very widespread and cosmopolitan plant, growing in a wide range of grassy habitats on most soil types. Other members of the group tend mostly to be garden plants that occasionally appear in the wider countryside.
Identification
Yarrows can easily be mistaken for members of the umbellifer famiy, due to their flat heads of many flowers and their fern-like or carrot-like leaves. However, a close look at the flowerheads will soon reveal a different structure, with each flower cluster being encased at the base by a set of green bracts called phyllaries - typical of members of the Asteraceae. The branches of the flowerheads also lack the distinctive bracts and bracteoles that are typical of the umbellifers. Most species can be told fairly easily by comparing both the flower structure and the leaves.
European Yarrow Achillea millefolium
Native. Widespread and very common throughout much of our region, on all but the wettest soils. Flowers June to September. Forms extensive, creeping patches of short stems, though can grow to 60cm or more in longer grass. Flowers typically white in wild populations, but pink-flowered plants are fairly common, too. Deeper red flowers perhaps owe their colour to gene flow with nearby garden plants, or may be garden throw-outs. leaves deeply cut, 2- to 3- times pinnate and oftn mistaken for carrot leaves.
 |
 |
 |
 |
| |
|
|
|
 |
 |
 |
 |
| |
|
|
|
Fern-leaved Yarrow Achillea filipendulina
Introduced as a garden plant from Central Asia. Fairly common in parks and gardens but only rarely reported as an escape from cultivation on roadsides and grassy places. Flowers July to September. A larger plant than our native yarrow, sometimes growing to over one metre in height. Flowers deep yellow in large, flattened heads. leaves less deeply divided than European Yarrow and the whole plant is strongly aromatic.
Compare with Common Tansy, which is superficially rather similar.
 |
 |
 |
 |
| |
|
|
|
 |
 |
 |
|
| |
|
|
Sneezewort Achillea ptarmica
Occurs as a scarce native in wet meadows and fens and scattered in a few places as a garden escape or throw-out. Flowers July to August. Stems variably 20-70cm in height, according to habitat. Flowerheads more open than those of European Yarrow, but each head has more individual florets in it and a greater number of petals arranged around the outside. Garden forms often have double-flowered 'pompoms'. Leaves rich, deep green, with saw-toothed margins.
 |
|
 |
 |
| |
|
|
|
 |
 |
 |
 |
| |
|
|
|
Cottonweed Achillea maritima
Fomerly native on beaches in East Anglia, especially on the Suffolk coast, but now extirpated and probably last recorded in the late 19th Century. Flowers August to October. A low plant with stems forming clumps, to about 50cm in height. The whole plant is covered in dense, cotton-like, white hairs.
 |
 |
|
 |
| |
|
|
|
 |
 |
||
| |
|