Metellina is a genus within the family Tetragnathidae (Long-jawed Orbweavers) with 6 species occurring in Europe/Asia and 2 species occurring in North America.
Metellina segmentata, which is probably the most abundant orb-weaving spider in Germany, was introduced in Canada.
When disturbed they will stretch their front legs forward and the others in the other direction, thus being able to hide on blades of grass or similar elongated substrates.
This is either Metellina segmentata or Metellina mengei.
It is impossible to identify the species from a photo.
However, Metellina mengei is usually found from May to July while Metellina segmentata is usually found later in the year, from August to October.
I took this photo on 29 August so it may well be Metellina segmentata.

Zanderij Crailo, Hilversum, The Netherlands, 29 August 2013