Oats (Avena species)

Below is Avena sativa - the most commonly cultivated oat species (and it also grows wild). Note the distinctive flower clusters, each flower looking a bit like an elongated pacman. This is typical of the many species of oat that you'll find growing wild around New Zealand.

By Andreas Trepte (Own work) [CC-BY-SA-2.5 (http://creativecommons.org/licenses/by-sa/2.5)], via Wikimedia Commons

This one is Avena fatua - a particularly common wild-growing oat around New Zealand:

By Miwasatoshi (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0-2.5-2.0-1.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons