Golden Rod – Solidago virgaurea.

Leaves and Stem
The leaves are quite long and thin (lanceolate) and may be irregularly toothed. The leaves near to the bottom of the stem may be 2 to 10 cm long, with short stalks (petioles). The leaves further up the stem tend to be a bit narrower than the bottom leaves.
The edge of the leaf may be 'hairy' - see image.
The stems may be downy - covered in small hairs (image at foot of page).

Flowers and Fruits
Golden Rod is a member of the daisy family (Asteraceae or Compositae). The flowers are composites; that is, they are actually many small flowers packed closely together into a compound head - which seems like a single flower.
The individual flowers that make up this compound head are called florets. These florets are of two types :
Disc florets - where the petals are joined together to form a tube which ends in small 'teeth'
Ray Florets - again the petals are joined together, but there is an obvious petal-like flap.
When the seeds form, wind dispersal is helped by white fluffy hairs.

Ecology and other notes
Golden Rod is a perennial. It may grow to a height of 70 cm i.e. 2 feet or more, but it can also be quite small.
It is quite variable in form and height.
The stems may be downy - particularly those supporting the flowers (see adjacent image).
Golden Rod may be found in dry, open places in woodland, or in grassland and rocky places.