Plant profiles > Passiflora
Family : Passifloraceae
The New Zealand passion flower is a very different plant from its most well-known relative, the commonly grown passion fruit (Passiflora edulis). In a genus of several hundred species (with a wide distribution), the endemic P. tetrandra is out on its own as the sole New Zealand representative. Passiflora is most heavily centred in South America, from where Passiflora edulis originates. The name, passion flower, does not have romantic connotations, but is rather derived from the passion (suffering) of Christ. Early Spanish missionaries related the floral and vegetative parts of the plant to a range of objects and people associated with Christ's crucifixion (such as the tendrils, which represent the whips used to flagellate Christ).
Our native passion flower is one of many climbing species which should be more extensively used; not only for their beauty, but for the range of situations in which they can provide solutions to common problems (such as providing sheets of foliage within confined spaces), and the additional layers of interest and dynamism that they can bring to gardens (through their association with other plants).
New Zealand passion flower; kohia
When considering climbers for garden situations, one often important characteristic is the density of coverage that a plant maintains. Certain climbers can end up with a rather sparse appearance (especially down low), as growth is focussed towards the ends of their branches and canopy1; whilst others (like Passiflora tetrandra) form thick curtains that are ideal for covering walls, fences or other support structures.
Although it is a relatively common feature of many of our forests, Passiflora tetrandra is not planted as often as it should be. In some ways, this is understandable; as the plant presents a vastly different face within nature than that which it assumes within cultivation (this is the case with many plants). Kohia is a very vigorous plant in its natural habitats; forming "large, glistening masses"2 in excess of 6m tall, and reaching up to 10m tall. It is therefore surprising that such a plant should be adaptable to being kept at a very compact size within gardens.
The photo above shows one situation within which kohia has been used to excellent effect, in providing a 2m high screen for a carport at the outstanding garden of the Hawke's Bay potter, Bruce Martin. For many years, P. tetrandra has formed a 2m high, dense curtain of foliage, which produces large quantities of fragrant flowers during summer.
An even more interesting application of this plant is to be found at the grounds of Oratia Native Plant Nursery, where it has been grown for several years adjacent to the smoko area. In this spot, P. tetrandra covers a small frame that is 1m high and less than 2m wide. Most other climbers would not have retained the even coverage of foliage that kohia does in this spot, especially with the challenging soil conditions of this small, dry garden bed. More importantly, it is an example of the capacity of kohia to cover a very confined area in an elegant manner. We use it for covering large walls (supported by wires); a purpose to which it is eminently suited, due to its rapid early growth, controllable mature state and the density of its dark green foliage.
Passiflora tetrandra grows naturally in lowland forests throughout the entire North Island and as far south as Banks Peninsula in the South Island. The sweetly-scented summer flowers are followed by orange fruits, which are a favoured food for birds. These, however, will only appear when male and female plants are planted together; as P. tetrandra is dioecious3, meaning that plants are either one sex or the other. Kohia was one of many plants that were discovered to science by Joseph Banks and Daniel Solander, who were the botanists to Cook's first voyage to New Zealand in 1769.
- This growth form (bearing the majority of foliage towards the tips) is ideally suited to growing up through trees and shrubs within gardens, as such a climber is less equipped to overwhelm its host (such as in the case of many Clematis).
- These are the words used by the great New Zealand botanist, Leonard Cockayne, in describing Passiflora tetrandra within his book, 'The Cultivation of New Zealand Plants', published in 1923. This book is an extremely interesting distillation of the knowledge and experience of the greatest genius to have ever worked on New Zealand plants. Cockayne was not only an authoritative figure within botanical science; he cultivated a massive range of native plants in his properties, many of which were subject to unusual experimentation (such as deliberately planting a species in conditions totally different from its natural station).
- The term, dioecious, is derived from the Greek, oikos, meaning 'housed', and di-, meaning two. This refers to the male and female sexual parts being housed on different plants. Such plants are therefore not self-fertile. As with humans and other animals, it performs the purpose of increasing diversity within any following generation. It is a significant feature of the New Zealand flora, and that of other island districts.