Circling the Okavango

In January 2004, Moffat Setshogo from the University of Botswana, D. Menyatso, our museum horticulturist, D. Mothomme, our driver, and I set off for Maun, south of the Okavango. We set up camp on the banks of the Thamalekane River. The next day we visited the Peter Smith Herbarium and headed off around the western side of the delta to Gomare. At the police station we revisited a giant Orbea and discovered that it had been collected locally. For 9 months I have been growing one, but still have not seen the flowers. I was astounded to find such a big specimen of Orbea lutea with its yellow flowers. We camped at Shakawe.

On the 7^th, after our spare tyre was repaired at the Botswana Defence Force Camp, we went up to Mohembo where there is a ferry across the river. We stopped to collect seedlings of Mimosa pigra, which reacts to touch by closing its leaves. We travelled on dirt road and stopped at the only known site of Habernaria pasmithii, an orchid named after the late Peter Smith. Unfortunately, the flood plane was dry and partly burnt and we didn't find any. All wasn't lost as I found flame lilies (Gloriosa superba) and a milkweed with edible fruit (Orthanthera jasminiflora). That evening we camped at Seronga. It can be reached by a two-hour boat ride (only P25) from the paved road on the western side of the delta. We collected a large number of flowering and fruiting trees along the river, including the sausage tree, Kigelia africana, with its big, woody fruit.

On the 8^th we drove north-east to the Buffalo Fence that separates cattle and wildlife. We entered the Selinda Reserve (with its giraffe, zebra etc.) and followed the flood plain of the Selinda Spillway (an occasional overflow from the Okavango). The Spillway denotes the presence of the Gomare Fault, which is one of three that form the delta’s shape. The Selinda Spillway led us to the Kwando River at a crossroads of water. Sounds impossible? The Kwando comes down from Angola, reaches the Gomare Fault, and does a right angle turn to become the Linyanti River and later does another couple of right angle turns to become the Chobe River, which finally joins the Zambezi.

An interesting fact is that the Mose oa Tunya or Victoria Falls is also formed by a fault that runs parallel to the Gomare. It’s all part of the southern end of the Great Rift Valley, which starts in Turkey! In addition, water from the Kwando occasionally crosses the fault and forms the Savuti channel, which ends in the Mababe Depression of the Chobe National Park. This network is merely a part of the fluid river system of Northern Botswana.

At the Kwando River, we visited James’ Camp (now Botswana Defence Force), but failed to find another rare orchid. That night we pitched our tents at the HQ for the Selinda Reserve. I had hoped to meet researchers there as the reserve is starting a herbarium, but they were all out.

On the 9^th we drove south to the Moremi Game Reserve, stopping (unsuccessfully) at the only locality in Botswana known for Orbea gossweileri, which is another purple-flowered stapeliad. We also stopped to remove a tree that elephants had placed across the road. At the North Gate we saw more zebra and giraffe, as well as waterbuck before we crossed a bridge of wooden logs into the Reserve. The branch of the Okavango here is known as the Khwai. We crossed it and drove out to Mboma Island with a park researcher, as required by my permit. He turned out to be an old acquaintance, B. Pelekegae. Years ago he had led me to the only known locality of the desert candle (Monsonia salminifolia) in Botswana, namely in the southwest at Tshabong. We discovered, however, that the localities for rare orchids that I wanted to collect were all out in the water. We then arranged with Dr Kurugundla, a botanist of Water Affairs (for which Peter Smith had also worked), for a boat to take us out onto the water at sunrise. That night we camped back at the North Gate. I looked for Orbea schweinfurthii, which has been recorded near the Khwai, but to no avail.

We started out with a boatload of passengers, but after a brief channel run the other intrepid three from Gaborone were left (at their request) on shore while we hunted GPS points on the water. We found orchids (Eulophia latilabris, which has 1m high leaves, and the smaller Eulophia tanganyikensis) at the first stop, but then the motor burnt out. Proceeding very slowly, we reached the nearest dock and fortunately did not have to wait long before a wildlife boat found us. The crew of the wildlife boat lent us a spare motor to continue our search. We found the second GPS point, but no orchids. Dr. Kurugundla had found a small one there previously and would continue looking. On the way back we encountered hippo, elephants, and large crocodiles while snacking on water berries (Syzigium cordata).

After picking up the landlubbers, we proceeded to the South Gate. We found paved road soon after passing through the buffalo fence. We reached Maun just in time to refuel for the drive home on Saturday. (The Government fuel point is only open on weekdays.) On Saturday, we were met by zebra strolling down the road next to the entrance to the Makgadikgadi National Park.

—Bruce Hargreaves

SABONET News 9.1: 75