Red Dead Nettle and Staggerweed
Lamium purpureum & Stachys arventis
Despite their alarming names these are two rather inoffensive weeds, more often found in gardens and crops rather than pasture as they prefer loose, fertile soils.
Although they have different scientific names they are both members of the Lamiaceae, and to the unitiated eye they can appear identical.
Both have rather wrinkly and downy leaves with indented edges, which grow in opposite pairs. Both have four-sided stems which tend to sprawl. In wetter conditions they may grow to 50cm, but will be much shorter in drier places. The flower heads are leafy, with whorls of tiny pink-purple flowers which grow in the axils of the leaves.
However, there are differences to be noted by the keen-eyed.
Red dead nettle flowers from September-November, whereas staggerweed flowers all year round. The nettle (which is not a true nettle and has no sting) has a two-lobed flower, with the upper lip arched downward over the stamens, and the lower spotted with purple. The flowers lobes are longer than the calyx. The staggerweed flower is paler in colour, with its upper lobe shorter than the lower and turned upward. The calyx is more prominent and the corolla protrudes only a small way.
The nettle leaves are heart shaped, can be up to 5cm long and 3cm wide and all have leaf stalks, with the lower leaves often purplish tinged. The staggerweed leaves are slightly smaller, less wrinkly, and the toothed edges are more evenly rounded, with upper leaves smaller and stalkless while lower leaves still have stalks.
The main noticeable difference is that staggerweed stalks are bristly-hairy, while red dead nettle stalks are smooth.
Staggerweed appears to have been given its name because in countries other than New Zealand it has been known to cause staggers in animals which have grazed substantial quantities of it.
Red dead nettle leaves, on a quick glance with poor eyesight, have a resemblance to the leaves of the true nettle. The ‘red’ descriptor probably comes from the purplish tinge on some leaves. I have found no reason for the ‘dead’ part of the name.
Staggerweed grows most prolifically in Nelson and Wellington provinces, although can be found throughout the North Island and down to south of Christchurch. Originally from Europe.
Red dead nettle prefers the higher rainfall areas of New Zealand, and originated in Eurasia.
In crops both weeds can be surprising hard to get rid of as they have developed resistance to many selective herbicides. However, some mixtures of two herbicides have been found to work, particularly in cereal crops.