More weeds and wildflowers - Yarrow and Sneezewort

             

Back in June I wrote a blog-post about a group of plants called Umbellifers  - the Carrot Family

(What is an Umbellifer? - and how to tell two of the commonest ones apart). In it I mentioned a couple of species which are sometimes mistaken for Umbellifers. One of these was Yarrow (Achillea millefolium), pictured above.

Even if you don't think you know Yarrow, if you live in the UK you will certainly have seen it - its feathery leaves and white, umbel-like flower heads are a very common sight in lawns, grass verges and weedy roadsides across the whole country. If you are a gardener you may be familiar with some of the cultivated varieties, including some pretty pink or yellow flowered forms.

Despite its appearance, Yarrow is actually in the daisy family (the Asteraceae, formerly known as the Compositae)  - if you look closely at the flower heads you can see that it is made up of lots of little 'daisies', but with white centres as well as white outer petals. Also, and perhaps surprisingly, each of these little 'daisies' is not actually a single flower, but a flower-head made up of several tiny flowers (or 'florets') - this is also true of daisies themselves and all the other members of the family, such as dandelions, thistles and sunflowers.

The first part of the scientific name of Yarrow - Achillea - is a reference to Achilles, the  character from Greek mythology, whose soldiers apparently used it to treat their wounds. The specific name - millefolium - means 'a thousand leaves' and refers to its feathery foliage. This is also reflected in one of the old names for the species, Milfoil.

Yarrow has a close relative in the genus Achillea, called Sneezewort (Achillea ptarmica). This is much less common in the UK than Yarrow and is usually found in damp grassland, although the plant in the photographs below was growing on an overgrown roadside verge in the North York Moors, and very close to some Yarrow, making it very easy to compare the two and look at the similarities and differences. The individual flower-heads look quite similar although they are bigger in Sneezewort and the way they are grouped together does not look so obviously 'umbel-like'. The leaves, on the other hand, are quite different, being long and thin with little teeth, rather than deeply divided and feathery.