Apodasmia similis

Searching for an upright oioi

Oioi for water sensitive design

We’re looking really closely at one of the most common plants in NZ, oioi or jointed wire rush (Apodasmia similis). Oioi is a very attractive plant for gardens with its wiggly stems that seem to look like they are shaking even when they are still (oioi means to shake gently or wriggle in Maori). It is a popular plant in roadside landscaping and streetscapes and grows well in water sensitive design devices such as swales and rain gardens. Plants in these settings need to be hardy and resilient to climatic extremes as well as be able to form dense habits to supress weeds. This is especially important in places like motorway plantings where maintenance is costly because it requires road closures or traffic management. Oioi is recommended as the top choice for roadside swales by Auckland Transport because it meets these criteria.

However the usefulness of oioi is reduced because of its tendency for its long leaves to arch out from the centre of the plant and sit on the ground (or ‘flop over’). This is not helpful in gardens in car-parks or along paths. The long leaves lie on paths and pose a trip hazard to pedestrians. Gardeners are forced to use line trimmers to cut the leaves which is costly and unsightly.

Because it is such a useful plant in water sensitive design (a particular interest of Auckland Botanic Gardens) an oioi trial was initiated at ABG in 2010 which aims to find whether there are shorter and or more upright forms of oioi that would be better for amenity uses. In addition we are looking at whether all oioi flops with age and if the sex of the plant (oioi is dioecious with male and female inflorescences on different plants) has any bearing on this habit.

We intend to continually add plants to the trial (and remove those that arch too much) and are really interested if you see a very short or an upright (non-arching) form of oioi either in amenity gardens or in the wild. So far this request has taken us to more unusual plant collecting places such as Birkenhead New World’s car-park and the side of the motorway accompanied by the Auckland Motorway Alliance. Contact us if you see some that you think we need to check out.