4 things to know about duckweed

• Duckweed is the world's fastestgrowing plant, and has the smallest flower of any plant.

• At Rutgers University's duckweed research unit, they can grow about five times the amount of duckweed per acre compared to maize. They believe they can get better growth once they perfect lighting, nutrients, and water temperature.

• Most research on duckweed as a superfood for humans uses a commercially cultivated strain of Wolffia globose called Mankai – it's not yet available in NZ. However, NZ native duckweed (Lemna minor) seems to have similar growth and nutritional values, with protein levels from 20-40%.

• People should only eat duckweed grown in sanitary, hydroponic or controlled conditions. In the wild, it prefers to grow in still, high-nitrogen water and tends to accumulate heavy metals. Some varieties may also be high in oxalic acid (2-4% vs 0.5-1% for vegetables such as spinach and chard). The levels can be minimised by growing duckweed in 'soft' (low calcium) water, and researchers are working on growing varieties that are naturally lower in oxalates.