Prof Lucas 'Kas' Holtzhausen has travelled over a million kilometres in search of the perfect marula, visiting over 100,000 trees and driving a Mercedes Benz into the ground in the process.
In a quest that has continued over a quarter of a century, he has searched most of southern Africa for the biggest, sweetest, juiciest marulas.
His journey is almost at an end, as he is in the final stage of submitting several marula cultivars to the international body that registers plant cultivars for commercial purposes.
Four of his improved cultivars have originated in the Kruger National Park (KNP), where Prof Kas has also found what he believes to be the largest male marula tree in the world.
This December, he will join Sanparks senior staff in planting out the cultivars in the last step of proving that they are genetically stable. Sanparks will have the honour of naming the marula cultivars when they are registered for commercial purposes, the first indigenous tree to achieve this horticultural claim to fame.
Prof Kas, a citrus and deciduous fruit specialist, became interested in marulas when a sergeant major walked into his university office with photos of a wild fig tree with 134 jeeps parked in its shade. The tree was growing near Crook's Corner at the Mozambique-South Africa-Zimbabwe junction. The sergeant also had a photo of a huge marula tree.
The photos and a book called "Food from the Veld" sparked Prof Kas' interest in indigenous fruits, and he decided that the marula was the most likely candidate to turn to commercial production. His search began years before marulas rose to fame in the movie "Beautiful People" where elephants were (falsely) shown to get drunk on marula fruit.
The movie brought the fruit to public attention, and helped create the concept of Amarula Liqueur, now sold in over 100 countries. In the beginning, Prof Kas was a lonely pioneer in marula research. In 2003, as keynote speaker at a fruit conference, he addressed over 70 people actively working on marulas. "The industry exploded before the research on marulas was finished."
The commercial implications of the fruit even led to industrial espionage, where a university from Israel obtained some of Prof Kas' genetically superior plants and tried to register them as their own research. Only his contacts in the industry prevented this intellectual theft.
Many fascinating facts are now known about marulas, including that marula oil is 48 times more stable than the very best olive oil, containing a natural preservative that still has to be identified. This makes it ideal for perfume and cosmetic uses.
The peel contains at least 150 flavourant molecules, and the fruit contains several times more Vitamin C than citrus. The marula cultivars that Prof Kas has been working on are being developed for different purposes. Marula trees have both male and female plants, with the males being ideal shade trees.
Female trees can be a problem as the fruit falls when green and hard, and is capable of denting cars. With a male cultivar grown on a grafted plant, the fast-growing tree could grace car parks around the country. One male cultivar originates from a tree near Punda Maria, which has a trunk circumference of 4.2 metres.
Female trees have been selected for fruit sweetness and size, making them ideal for eating, juicing and fermenting. Exceptional female trees were found near the Skukuza helicopter hangar and near Kanniedood Dam in Shingwedzi.
Four other cultivars from Namibia, Tzaneen, Phalaborwa and Mhala town (near Kruger Gate) are also ready for registration, and Prof Kas is excited about the prospects of another tree near Albasini Ruins. Marula trees make productive garden plants - about three tonnes of fruit can be expected from a healthy tree planted and watered in a garden.
Their productivity has also led to financial rewards for rural people living in the lowveld, who collect the fruit and take it either to the Amarula factory in Phalaborwa or to a processing plant in Bushbuckridge, where it is used to produce jelly.
The fruit harvesters, mainly women, earn money both through harvesting the fruit and extracting the nuts from the marula seed, a difficult task that cannot be performed by machinery.
In the many miles that Prof Kas still travels for his beloved marulas, one of his most rewarding trips takes him along a stretch of road outside Lephalale (Ellisras). Here his grafted marulas were planted out ten years ago. "It is the most beautiful sight. For 20 kilometres the whole sidewalk is lined with marula fruits the size of a small orange."
Prof Kas dreams of the day when other indigenous fruits are given the recognition that marulas now receive. He says that the improved marula is "Truly a real African Renaissance contribution to the economic horticultural world."
Put five litres of water in a bucket. Find a double handful of yellow marulas. Scar the skins by pricking and place in the water. Add a pinch of yeast and two cups of sugar. Leave for two days until the fruit floats.
Strain through a cloth, place in the fridge and drink. A tiny amount of alcohol gives the drink a great tang, and Prof Kas says it tastes so good that it never gets to stay in his fridge for more than a few hours, especially with children around.
By Melissa Wray