Ryegrass - Annual

Perennial ryegrass (Lolium perenne) is an important cultivated grass species which becomes a very competitive weed when growing in cultivated crops. Though it is a perennial species it will still produce seed in the first year of growth. Generally germinating at the same time as the crop it grows quickly and competes aggressively for space, light, nutrients and water. Uncontrolled perennial ryegrass will significantly reduce yields. To identify look for young plants between the crop rows, young plants are upright and the leaves have prominent veins. As plants get bigger the leaves are shiny underneath and these stand out, especially on breezy days. Later, when in ear look at the seedhead as ryegrasses have one edge of the seed against the axis which means the flat side of the seed is visible.

Californian thistles (Cirsium arvense) are a perennial thistle that is a major weed of pastures and crops throughout New Zealand. It grows and spreads in patches with a spreading underground root system. In the winter the foliage dies off from frosts with new plants growing from the underground root system in the spring. The root system is easily broken up by cultivation but new plants originate from these and can be very problematic in crops and new pastures.

Rayless chamomile (Matricaria dioscoidea) is an erect annual, found in waste and cultivated ground and footpaths. It is resistant to cold, trampling and many herbicides. The greenish yellow leaves have a feathered appearance and give off a pineapple scent when crushed. The composite flowers are yellow with green tinges and growing at the end of the branches. It is not particularly common in New Zealand, and found chiefly in the North Island, and the north and east of the South Island.