Rubus cissoides

Rubus cissoides is the same genus as the blackberry and raspberry resulting in several similar features. The bush lawyer is a woody climbing vine consisting of a relatively weak stem which relies on the support of shrubs.[3]

The bush lawyer is a dicotyledonous plant meaning the leaves consist of a branching vein network. The leaf surface is smooth and hairless, whilst having serrated edges. The leaves are long and narrow in shape, forming in groups of five leaflets.[1]

A key identifying feature for the bush lawyer is the reddish coloured hooks located on the branches. These hooks are on the underside of the branch to enable the plant to essentially grip as it climbs to heights of up to four meters.[3]

The bush lawyer has a white flower and also produces a yellow to red coloured berry.[1]

R. cissoides flowers between the months of August and December. The flowers produced are white in colour and are deciduous meaning during the winter period there are no flowers to be seen. The individual flowers are either male or female flowers. Both male and female flowers cannot be found on the same plant. Pollination of these flowers occurs via insects such as bees. Once the flowers are pollinated the plant also produces the orange/red drupelets between the months of November and April. During this period the drupelets drop seeds. They are eaten by animals such as possums allowing the seeds to be dispersed throughout the forest.[5] The plants then germinate normally around spring when there is a warmer environment for the plant to establish in.

The younger plants/seedlings have a different leaf formation to that of the more mature plants. The more established plants have pinnately compound leaves, whereas the young leaves simple.

Initially the stem of the plants is rather thick and stable to allow the young plant to find vegetation to climb. The young plants can support themselves up to a height of 60 cm before requiring stability.[6] If the young plant cannot find vegetation to grow up it will spread over the forest floor until it finds an appropriate shrub to establish itself on. The hooks on the leaves and branches allow the young plant to climb up shrubs easily to establish a place in the canopy where it can receive light.

R. cissoides is known to grow rapidly. Once the plant has begun to climb, when it reaches a suitable height and is mature it will begin to produce flowers in August to December.

R. cissoides has adapted to many different soil types throughout New Zealand. However, there are some soil characteristics which enable it to grow better.

R. cissoides prefers soils with a moderate to low level of sand. Sand consists of large particles with large air pore spaces. This means the water drains rapidly through these particles. If a soil has a large proportion of sand it can often lead to a relatively dry soil.

R. cissoides prefers a moist environment, so soils with high sand content are not ideal. In contrast soils with a relative proportion of clay suit the preferred growing conditions of the bush lawyer. This is because clay particles are very fine, and have a high water holding capacity. Having a high water holding capacity provides the bush lawyer with a moist soil.[5]

R. cissoides is very versatile in terms of the pH of the soil in which it grows. It is well adapted to acidic, neutral and basic soils. However, highly acidic and basic soils may have negative implications on growth.

R. cissoides cannot tolerate shaded environments. You will often find it in sunny areas of the forest. This is also the reason why it climbs high in the canopy.

R. cissoides requires essential plant macronutrients. There are many nutrients which plants require to maintain good growth but the main three are nitrogen, phosphorus and potassium (NPK).[7] Out of these three macronutrients nitrogen is the most important for plant growth. Nitrogen is essential for the process of photosynthesis to occur. Photosynthesis produces energy for plant. R. cissoides will need a wide range of nutrients in the soil to remain healthy, especially NPK.

The hooks on R. cissoides are mainly used for assisting with climbing, but also assist the plant in terms of protection from predation. In New Zealand there are a lack of browsing mammals, which may account for the lack of predation against R. cissoides.[6]

The hooks on the leaves and the branches are important when looking at the predation of R. cissoides. For example, the berries found on the plant are edible and palatable. This would make them attractive to bird species. However, the hooks mean that birds cannot land on the plant to feed on the berries therefore reducing predation.[5]

R. cissoides does still face a few predators in the New Zealand bush. These predators include deer and possums. Possums have been known to eat the berries and also the flowers of the plant. Both deer and possums remove small amounts of foliage from the plants.[8] Both deer and possums have been known to eat the leaf litter.

There is a disease that effects R. cissoides but is not extremely rampant (not a large concern in the wild). This disease is a fungus called Phragmidium violaceum, or more commonly known as blackberry rust. This fungal disease appears as black patches on the leaves, the spores germinate in spring and are dispersed by the wind. Blackberry rust can decrease the number of berries produced by R. cissoides.[9]

R. cissoides has multiple cultural uses and many of these were created by Maori.

The berries of the plant are edible but are said to be tasteless. The sap inside of the stems can be extracted and is used in cooking, it can be eaten plain or it can be cooked.[3]

The berries can be crushed up to form a dye which is blue/purple in colour.[5]

The Maori often used many parts of R. cissoides for medicinal purposes. The bark of the stem was used as a cure for abdominal pains, and the bark from the roots was used as a cure to stop diarrhea. To relieve chest congestions and colds the Maori used small portions of crushed up leaves.[9]

Other than medicinal uses Maori also had other uses for parts of R. cissoides. In the eighteen hundreds it was recorded that local Maori caught fish using a net crafted out of the vines of R. cissoides.