‘Bush potatoes’ from Cow pea plants in Namibia

Cow peas (Vigna vexillate subsp. lobatifolia) are strong climbers, which resemble Mung beans. The stem of this vine is up to 6 m long and develops trifoliate leaves. Its flowers resemble purplish pea-flowers, and the pods are abt. 7 – 9 cm (2 ¾ – 3 ½‘’)  long, thin, linear, and slightly recurved and twisted. The flowering time is in summer after the first good rains. Most important for human consumption are its tubers, which are called ‘Bush potatoes’ by local people in Namibia. Distribution of this Vigna subspecies is restricted to Southern Africa. For details, see this Link.

Cow pea tubers (bush potatoes) are regarded as one of the most important food plants for Ju/’hoansi people in their habitation zones within Southern Africa. Especially in wintertime bush potatoes are, besides of Manketti nuts, the most sought-after wild food items.

How to find bush potatoes?

Generally, finding Cow pea plants is difficult. They grow mainly in sandy bushveld biomes among a variety of other similar looking plants, shrubs, and bushes.

In summertime, its trifoliate leaves can be spotted, but can also be easily confused with other trifoliate leaves in the area. But Jul/’hoansi women, who do mainly wild food plant foraging, developed a good eye for such differences. Ju/’hoansi men on the other hand are going purposefully after the meat. They only collect useful plants when coincidentally finding them during hunting.

It is far more difficult to find bush potatoes in wintertime, when shrubs and vines are void of leaves and only the dried pods of Cow peas are visible. These pods however are very inconspicuous among the shrub branches, as they got the same color as all the stems around. Furthermore, they got the same diameter as the twigs and are slightly curved. I would say, they are therefore perfectly camouflaged. Only the twist in the pods can be seen. And for these twists and a bundle of two or three of such pods from one node the collectors are looking out. The foragers now retrace the vine back to the point, where it emerges from the soil. In most cases this point is close to a bush and the vine itself is nearly impossible to distinguish from the bush stems.

Digging for bush potatoes

By vertically digging down along the vine stem, tubers will be found at a depth of about 25 cm (10’’) and deeper. Than, the sand will be loosened with a digging stick and scooped out by hand. If there are roots from horizontal roots of the neighboring bush, these have to be broken and removed from the hole. The tubers itself are light brownish in color and look very similar to raw potato skins. These tubers are variable in size, but always about 3 cm (1 1/2’’) in diameter with different lengths and connected to each other by one threat-like root. How deep these tubers are rooting is not known to me, but due to practical restrictions, the hole can’t be dug deeper than about 60 cm (abt. 2 ft).

It is also a good experience to feel by hand how temperature and humidity changes within these holes. At the surface, the temperature of the sand depends on ambient temperatures, which was in our case 38 degC (abt. 100 degF), so the first centimeters of sand were searing hot. By digging down the sand just about 15 cm (6’’) deep, the sand was getting considerably cooler and felt humid. At a depth of abt. 30 cm (abt. 1 ft), it was relatively cool in the hole, and the sidewalls felt wet. This was also the reason why it was possible to dig a straight, vertical hole, which did not cave in. It also reminded me on the narrative that Khoi-san people dug people into the sand who were heavily dehydrated. This practice makes absolute sense for me now.

Eating bush potatoes

There is a thin peel over the tubers and below that peel there is a white, fiber-less interior mater, which is eaten either raw or roasted. For eating raw, the peel will be cut away and the inside mater tastes like very mild radish with a quite high content of water.

For roasting, the tubers will be shallowly buried in the hot sand next to a fire and thinly covered by some more hot sand. The peel will start popping here and there when water inside the tuber is evaporating. After about 10 min roasting in sand, the tubers are done. They can be peeled and eaten and taste like roasted potatoes.

According to literature, the protein content of these tubers is abt. 15%, which is high, compared to the up to 7% for potatoes and yams and is 8-fold higher than for sweet potatoes and tapioca.

Lessons learned about Cow pea tubers

• Cow peas can be found around the globe in tropical and subtropical countries
• They have got very inconspicuous leaves and pods to find them
• Most importantly, they have got edible tubers, which can be eaten raw or cooked
• Taste of raw tubers is like radish and of cooked ones like potato