The Cactus Patch
Volume 9       December 2006      Number 12

Red Sands & White Pans
A Letter From Bruce
by Bruce Hargreaves

On the 17th of October I joined a Millennium Seed Bank trip to the dry southwest of Botswana. (The MSB is sponsored by Kew Gardens in England and is collecting seeds from rare and endangered species. The seeds are stored both in the country of origin and in the UK.) Our first stop was at Sekoma Pan, which is about 200 km (125 mi.)due west from Gaborone. Here we expected to find Orbea knobelii, but instead found Ruschia cononotata. This was my first time to see wild Ruschia in Botswana (although I saw plenty in Lesotho). We had it in the herbarium, but not from Sekoma.

Then we proceeded south to Tshabong where we camped at Berry Bush Farm. The berries are not commercial ones. The name refers to the abundance of Grewia bushes with edible (and fermentable) fruits. The only problem with the place were the constantly calling peacocks. (The pigs, chickens and camel were not a problem.) The owners invited me for burritos and sangria that evening.

Next day we met with the chief and climbed the hill in town (and once more failed to find Euphorbia rectirama which I saw there in the distant past). Then we went to the pan east of town (the one in town is ruined) and found more Ruschia as well as Sarcocaulon salminiflora, both of which were expected and had flowers and fruit.

Once again we failed to find Orbea knobelii which is recorded for there. I also found a young leopard tortoise, some spotted sand lizards and three-striped mice. We then had lunch in town and headed south. Just a short ways out of town we found a population of Euphorbia duseimata with one in flower. This is the first time I have seen more than one plant at a time, so it will allow me to make observations on variations and the relationship with E. maleolens. It differs from the latter in being sand-adapted with a long thin tuber and branches that start below the surface.

The third day we followed the Malopo River bed (both a road and the boundary with South Africa) to the south west. The sand in the riverbed was damp and we found plants of Anacampseros subnuda in the rocks. We reached the Bokspits area at the southwest corner of Botswana and stayed at the Vaalhoek Village Development Centre rest house. Only two of us paid the P15 ($3) for rooms. The rest camped in the courtyard (I guess they want to spend their per diem elsewhere).They did use the kitchen (only P5 or $1 per night).

On the 20th we set off to the north through the red dunes. (These are destabilized due to overgrazing in a dry climate. Most of Botswana is wetter and has stabilized sand with trees and grass - but that is changing.) Our first stop was to collect seed of Parkinsonia africana, the green-hair tree, which looks a lot like its American cousin the palo verde. Next we tried to find Hoodia gordonii but only managed to find a large dead one which had previously been seen alive. I guess our garden plants were not the only ones killed by rain this year. Further north we stopped at a calcrete ledge on the Nosop River bed and found lots of Ruschia. We failed to find the Stapelia flavopurpurea which has been collected from there. I have never seen it in the wild.

From there we proceeded north into the Kgalagadi Transfrontier Park. Many of the plantings at the Botswana entry had died, but we did find Euphorbia bergii in flower and Adenia oleifolia in fruit. There was also a black tree skink, a ground agama and some more spotted sand lizards.

We went to the shop at the South African entrance and bought cold drinks. They also had a dead Hoodia but there was a live one as well. Next to the Hoodia was the look-alike Pine-cone Cactus ( Tephrocactus articulatus var. inermis) from Argentina! We also saw a planting of this at a village in Botswana. Next we went back toward Bokspits and collected seeds of Aloe hereoensis (from the few survivors- most died years ago). We also located Tridentia marientalensis and more E. bergii. That night I was glad I had a room as it dumped rain! This was welcome as it broke the intense heat.

Next morning we went to pay for the room and found a number of plants of Calotropis procera. The older plants had dead stalks and we were told this is due to the cold winters. This may help slow down the invasion. Another invader in the area is mesquite. This one is quite serious! Proceeding back east we found a calcrete cliff with more Ruschia and plants of Zygophyllum pubescens in flower and fruit. We also drove aways back into the dunes, but there was nothing interesting.

Next we stopped at a house above a calcrete ledge. There was a huge nest of sociable weavers next to the road up. At the house there were ordinary prickly pears (Opuntia ficus-indicus), spiny prickly pears (also Opuntia ficus-indicus although some call it O. megacantha) and the Boxing-glove Cactus (Opuntia sp.). Only the Boxing-glove had spread, although the others have invaded elsewhere in Botswana. Most horrible of all were the tumble weeds (Russian Thistle) there. This is a new pest in Botswana. On the plus side we found a pair of Eagle-Owl Chicks on the ledge! We spent the night back at Berry Bush Farm and returned to Gaborone on Monday.

As if this weren't enough, the MSB held a regional workshop in Gaborone starting on the 30th of October. There were representatives from South Africa, Namibia and Malawi as well as Botswana and Kew Gardens. We had presentations on work in each country so far and ended with a discussion of the future. The program ends in three years. What then? Various ideas have been put in motion, including mine which is to get funding from the tourist industry which has a stake in protecting the environment. On Wednesday we all went out to an area near Kanye where a rare Rhus species was once collected. (Fortunately none of the species here are dangerous like the related poison oak.) Just as we were about to return for lunch I found a Rhus, but it was only about 10 inches tall! I suggested the ubiquitous goats might be responsible for the size. I also found a five-headed plant of Euphorbia maleolens. The workshop ended with a dinner at the Livingstone Room at the Grand Palm -all you can eat buffet including Mongolian BBQ.

It hasn't all been MSB. We heard Vivaldi's Gloria sung by a new choir (I think ours can retire now) on the 28th and went to a wedding for Polly's friend Dineo's son down at Good Hope on the 29th. I went to the museum in Mafikeng on the 4th of Nov. to find out about the stage-coaches which ran from there through Bechuanaland to Bulawayo. They had a display which mentioned Palapye as a stop, but there was no mention of Gaborone. I guess the old building in our Botanic Garden just wasn't an important stop.

The film club continues to show fantastic movies. On the 12th of October they showed "11'09"01" which was done with 11 directors from 11 countries each segment lasting 11 minutes, 9 seconds and one frame. All used the twin tower attack as a theme but in quite different ways. Originally this was scheduled for the anniversary of the attack, but mechanical problems delayed the showing. Another remarkable film was "Moolaade' ", filmed in Burkina Faso by the Senegalese writer and director Ousmane Sembe'ne. I had never seen any of his films but have read his book "God's Bits of Wood" (which is a little better in the original French). The film tells the story of women who stand up against genital mutilation in a remote village. They succeed, but the price is high.

Finally, I received a book from Ian Martin of the Eden Project in Cornwall. (This is a remarkable Botanic Garden built in a quarry.) He had visited Botswana (he is curator for arid and semiarid lands) and asked if I wanted a copy of "A Brain for All Seasons - Human Evolution and Abrupt Climate Change" by William H. Calvin (2002, U. Chicago Press). In some ways it is a strange book (He calls the Kalahari a desert while stating the Namib is much drier and talking about the comparable area in East Africa as Savanna!), but the overall message is important. In commenting on the debate as to whether climate change is "natural" or man-made he says, "It's like estimating the time until the bathtub overflows when the water is left running: it makes a lot of difference if there is also a kid in the tub, bouncing around." Incidentally, at the MSB workshop we were presented with horrible statistics regarding the future of plants at the present rate of global warming. It seems the hardest hit areas will be the succulent-rich Cape, Karoo and Namib areas of Southern Africa. They have nowhere to go and will become extinct.

Camel munching on berry bush (Grewia)

Adenia oleifolia

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