September 1997
211

JOURNAL OF THE
TREE SOCIETY OF ZIMBABWE
P.O BOX 2128
HARARE

MATABELELAND CALENDAR
Sunday 7th September. All day visit to Esigodini – Colin and Judy Martin's farm. The Tree Society’s last visit here was in 1990. Please meet at Girls' College 8-8.30.
Sunday 5th October. Half day visit to Hillside Dams. Meet at Girls' College 8-8.30; we will be looking at a particular group of trees for identification.
Friday 31st October to Sunday 2nd November. Week¬end trip to Gwaai Valley Safaris overlooking the Gwaai River Valley. Rates per person per night as follows: -
1) Basic use of campsite. $43.00 (No tents supplied)
2) Camp site with tents and beds $64.00
3) Self-catering lodges $128.00
As long as we know beforehand, meals can be taken at the following prices: - Breakfast - $45, Lunch - $45 and Dinner - $77. Any combination of opinions can be catered for, but please let your Committee know soon if you want to participate in this outing, preferably before the 6th October.

SUNDAY 3 AUGUST 1997 BULAWAYO BRANCH
I suggest that the average person's concept of a tree is a pretty narrow conventional stereotype – trunk, branches, and leaves which may or may not be shed.
A glance at the illustrations in any reputable tree book should dispel this notion immediately and expand the mind.
When I was transferred to Bulawayo, just over 30 years ago, l was less than thrilled. Of course I had been here a few times. The people were friendly, but provincial. I found the general landscape particularly uninviting. It was flat, and the dominant trees were arranged in seemingly endless rows. Most were riddled with thorns.
How little did I know! Still, I would learn of the wealth of succulent riches that are around this place.
Then I saw aloes in bloom. Immediately, I was "hooked.” Some people regard the genus Aloe as a thorny excrescence, scrupulously to be avoided.
But St Matthew wrote in his sixth chapter: ¬"Consider the lilies of the field how they grow. They toil not, neither do they spin. - Even Solomon in all his glory was not arrayed like one of these.”
The Aloe is a member of the lily family, now called ASPHODELACEAE – Elysium's immortal flowers. Of the some 30 species that inhabit Zimbabwe, only 3 are classed officially as trees – Aloe arborescens, Aloe littoralis and Aloe excelsa, "excelsa" means "high."
On August 3rd this year, a small procession of cars wound its way through the city to the western suburbs. There can't be very many cities that enable their residents to become immersed completely in the wild as easily as does Bulawayo. Every exit road from town provides access to a small wonderland. And each is as diverse as chocolate is from coffee, from chalk, or from cheese.
The untamed area within Luveve is quite heavily wooded. It becomes apparent that it used to be even more heavily wooded. The depredations of humans wielding axe are everywhere. There are also a rich variety of trees there.
Combretum, Commiphora, Acacia, Tarenna, Vangueria, Bridelia, Terminalia, Crocoxylon, Albizia, Kirkia, Lannea, Dombeya, Ficus, Gardenia, Euclea, Maytenus, Mopane, Pseudolachnostylis Ozoroa, Dichrostachys, Pappea, Rhus, Ximenia and Strychnos were only some of the genera I encountered personally. A fire had raged through here and this facilitated walking.
But my attention was magnetised by the aloes. Aloe excelsa was everywhere on the numerous rocky ridges, and almost all were in glorious flower. There were very tall specimens, some with 2 or more panicles, all irradiating the brown winter landscape with their rich red spikes.
There were also some with orange flowers, and a few flashes of yellow identified some hybrid excelsa X aculeata. These plants lack the stature of the pure excelsa. There were extensive colonies of Aloe aculeata and Aloe chabaudii, providing proof of hybridisation. These were heavy with seed, their flowering being long past.
There was the trilling song of sunbirds as they fluttered about, collecting nectar, and simultaneously pollinating the inflorescences. I saw scarlet-chested, white-bellied and Marico sunbirds.
In the cloudless sky, high overhead, an eagle was stilling, before resuming its lazy circling. The sound of spring rang out. It was the weird up and down and roundabout song of the 3-striped Tchagra.
While the others climbed one of the higher kopjies, a nightjar was disturbed and took flight like a faded leaf, blown by an erratic breeze. I sat below and watched a little flock of scaly-¬feathered finches, as they searched diligently for morsels.
A tea break was suggested and half the outing decided to go home. After tea Anthon went to rescue some uprooted plants, while I was attracted to a Hamerkop nest a few yards down the road.
On the kopjie below the nest I discovered some white excelsa variants. Anthon explained how these were the result of many years' "back-breeding.” Many, many years previously some aloe had thrown out an albino variant, which then proceeded to breed with the red-flowered ones. The resulting plants bred again, and this went on until the present progeny evolved, producing red inflorescences that become white when the individual segments of the racemes open.
We identified 4 of these variants and found a couple of Aloe greatheadii that had had their flowers aborted, probably as a result of insect damage.
I saw only one species of Euphorbia, - Euphorbia ingens, and I saw also only one stapeliad – Duvalia polita.
There were a large number of excavations, which I theorized might have been where Fockea were removed for muti. A Marula bore fresh scars where bark had been taken, almost certainly for this purpose. In one place it appeared that spells or magical incantations had been performed. A number of trees were split longitudinally at a juncture of branches; wooden wedges were jammed into the fissures, together with pieces of blue cloth.
It was a most educational, satisfactory and beautiful outing, and we thank Anthon for his guidance and instruction.
Norma Hughes.

BOTANIC GARDEN WALK: 12 JULY 1997.
Ten people gathered in the Botanic Gardens to continue the session on palms. The list of palms in the Gardens, which had been prepared by Maureen Silva-Jones, has 61 species on it and in the hour Tom showed us a large number of these species. The purpose of this note is simply to mention some of the more striking ones that we saw.
Near the Herbarium grows Acoelorraphe wrightii (Paurotis). This is a multi-trunked swamp plant with palmate leaves, occurring naturally in the West Indies and in N. America (Florida). Despite its wet native habitat, it has done very well in its current relatively dry site. Butia eriospatha is a real savannah palm, occurring in Argentina. It has pinnate leaves. Its specific name means "red spathe" and it does indeed have an enormous erect spathe which subtends the inflorescence. The spathe is long and narrow and on these trees it was more brown than red.
A remarkable climbing palm was Calamus rhabdocladus. The leaves are basically pinnate although the leaflets appeared to occur in pairs along the pinna rachis. The inflorescence was very prickly and appeared to be a modified climbing structure.
Thrinax acanthocoma has an incredibly spiny trunk. The spines are rigid and about 10cm long. The plant itself has palmate leaves and comes from Cuba.
Tom pointed out how the branches of Neodypsis decaryi grow out in three directions. It is a Madagascan endemic with pinnate leaves. The base had been damaged by tractors mowing the botanic garden lawns and Tom mentioned how the tree never re-grows.
Unfortunately, there were far too many palms to discuss here (or for a novice like me to take in, for that matter). Our great thanks to Tom for yet another interesting walk.
M.A.H.

POTE VALLEY 20 July 1997
Sunday morning found us once more on the road to a Tree Society outing, this time travelling through the beautiful and fertile Enterprise valley towards Shamva. We were late as usual, but the Society has a very forgiving attitude to unpunctuality; unlike birds, the trees will still be there however late one is. Fortunately, we were not too late to enjoy a cup of tea and a sandwich on the lawn of the home of our hosts, Frank and Pam Wilson, at Burnside Farm in the Pote valley near Bindura. It was a lovely day, warm and sunny, a pleasant change from the cold grey weather of Harare. After tea, about 30 members and visitors and one dog drove through the tobacco lands to the foot of a range of low hills, up which, under the knowledgeable eye of our Chairman, we began to wander in search of interesting trees. The hills were sand and granite, covered with very varied vegetation, especially along the small stream that trickled peacefully over the rocks and through a steep-sided gorge beside our path. The first tree to catch our eye, which is always the one that I remember best, was Swartzia madagascariensis, the snake bean, instantly recognisable by its long, black cylindrical pods. We learned that it does not occur in Madagascar, its specific name being the result of a misunderstanding over the origin of the first specimen, that the pods are used as a fish poison, and that cattle develop a red discolouration of the urine when they eat the pods, which they relish. The tree is also being investigated for its antifungal properties. Thereafter, new trees came thick and fast; I recorded 52 species, and I am sure I missed a lot. We came across several Diplorhynchus condylocarpon, with their pale green-yellow drooping leaves but without their distinctive paired horn-like pods. This tree produces white latex that becomes quite rubbery as it dries; it is popular for reclaiming mine dumps, as it is very tolerant of the toxic elements that are often present. Large specimens of Brachystegia glaucescens were prom¬i¬nent as we climbed the hill, and along the stream we found Syzygium cordatum, Englerophytum magalismontanum, Olax dissitiflora, Diospyros natalensis, with its small, bright green, glossy leaves, Euclea racemosa, Rhus longipes, and a nice specimen of Ficus verruculosa sprawling characteristically across the rocks with bright red fruit arranged along its branches. We also saw, and kept well clear of, a buffalo bean carrying a pair of browny-yellow pods; the pods bear hairs that are incredibly irritating if one is unlucky enough to brush against them. There is little colour from the trees at this time of year, but the variety of greens of the leaves was relieved by the purple of Flacourtia indica and the red tinges of Faurea saligna. More colour was provided by the flowering aloes and shrubs, particularly (Iboza) Tetradenia riparia, the ginger bush, with its massed sprays of minute mauve flowers, growing, as its name implies, along the course of the stream. We tested our identification skills on the trees that had lost their leaves and were successful with Lannea discolor, with its characteristic pattern of branching, Euphorbia matabelensis, with its three pronged forks, Cussonia arborea, with its stubby branches and corky bark, and Sterculia quinqueloba, with its smooth, creamy, flaking bark. At last, saturated with names and leaf shapes, we descended to the car park for a leisurely lunch, keeping our minds active as we tried to identify the trees under which we sat without the help of our tutor.
Some of the party left for home to watch the final round of the British Open Golf Tournament on their dishes, while the diehards strolled down to an attractive little dam nearby, fringed with reeds and covered with Water lilies. We saw a variety of waterfowl, cormorants, darters, ducks, Dabchick, coots and Jacana, but not much new in the way of trees, apart from a grove of Dichrostachys cinerea and a number of small Terminalia sericea. By then it was time to take our leave of our hosts, and we headed for home, some by way of the rock paintings at Lion’s Head, the others directly back to their firesides in town after another lovely day in the country. We are so grateful to the farmers who make us so welcome and allow us to visit their favourite haunts among the trees and kopjies.
J.A.L.

GOLDEN ORB SPIDERS
On nearly every tree outing contact is made with the strong golden webs of the exquisite orb web spiders. Their biology is fascinating and for some of the observations acknowledgement must go to Cheryl Haxen and her Biology classes.
The web itself is made from silk of many threads pulled together from the spinnerets and is incredibly strong as these of us who have walked into the strands of web between trees and bushes well know. The tensile strength and unique properties have kindled interest in its use for cosmetic surgery, design for fibres to hold together and contain explosions in the holds of aircraft. If a piece of web is pulled apart it will billow out into many fibres. A single spinneret can have up to one hundred spinning tubes. The web is covered in a sticky substance to trap prey and is fairly fire resistant. The angling and design of many of these webs are engineering feats. The orb spiders commonly encountered belong to the genus Nephila and the females are large with bodies of over three centimetres and a much bigger leg span. The colour is black with striking gold patterns, which could be described, because of their amorphousness, as inky doodles. The abdomen is non-segmented and oblong and dorsally arched ending in finger-like spinnerets. The long slender legs in all their elegance span several parts of a web as well as enabling the spider to hold onto a single strand. The last joint called the tarsus ends in two claws and a third claw is formed from a pad between the claws. If a third claw is not formed the pad or empodium is sticky for clinging onto fiat surfaces.
These spiders usually move to the tip of the web where it joins a branch if disturbed. They do not attack and are non-poisonous to humans.
The female is nearly ten times the size of the male. In the one web the magnificent female had three rather pathetic consorts who looked like large pinkish-brown ants. It is advisable to be as unobtrusive as possible in a web. The female will normally devour the male. Courtship is a precarious business and the male taps on the web to soothe and placate the female. Once she is receptive to his music he hurriedly inserts sperm using a leg-like appendage, which can be broken off and discarded in the need for quick escape. Fortunately the ordeal does not have to be repeated because the female can store sperm for future reference.
The male has to strum and pluck the silken threads like a Romeo with a guitar.
Other opportunists take advantage of the females’ musical penchant. Tiny round brown and yellow spiders existed happily in the middle of the web where most of the encased insects were located. These were arranged along a strand like a systematic and logically designed larder. These little thieves play the right music and once she is placated they rob the pantry of the beautifully packaged food parcels. They may feed directly, sucking up the juices, or hijack the entire package by cutting the supporting thread and lowering the goods out of harms way to be consumed at leisure.
Spiders inject poison to immobilise the prey which once subdued can be trussed up in silk. The salivary gland injects enzymes, rendering the prey liquid. Spiders like to slurp up their soup. The empty shells or endoskeletons can be discarded or arranged in the web in a methodical manner. In some instances the web should remain balanced and transmission of vibrations should not be muted by trash.
Many people experience abhorrence at the sight of spiders. The dangerous spiders are very innocuous discretely hiding in grass sheaves or under window ledges and belong to the genus Lecrodectus and cause excruciating pain and a mortality of five percent in untreated cases. The black widow spider is common but fortunately very shy. Both the black widow and its relative the button spider are common in Zimbabwe. The bite venom is a neurotoxin (nerve poison). The American spider Loxoceles has a painless bite and the degradation of tissue may take months and in some cases the damage can only be repaired by a skin graft. This genus occurs in South Africa and Zimbabwe.
Two members of the Tree Society have been ill for weeks with suspected spider bites. One was encountered in a shoe and a cytotoxin was injected that caused a lesion that lasted for weeks and affected the whole leg. The other person was sick for three weeks after receiving a bite on her back, which left an ulcer where the tissue was breaking down, she complained of swollen glands and just not feeling well. In both cases the culprit was unobserved and not identified. A very common house spider wanders around at night in search of prey and is suspected of biting humans causing a swollen tender spot developing into an ulcer. These spiders make small silken retreats where they repose by day. The spider is yellowish with dark mouthparts. Other spiders can give nasty bites but are not dangerous. The much feared giant baboon spiders with their hairy coats and giant size are incorrectly called tarantulas. The baboon spiders lurk in their silken burrows and hunt by pouncing on their prey, which can include small birds. Most spiders are shy and mind their own business and it takes provocation to make them bite.
Mary Toet

TREES AND OTHER PLANTS OF DAVID LIVINGSTONE’S ZAMBEZI EXPEDITION 1858-1863
Continued from Tree Life No 210 August 1997.

PEPPER: 15 October 1859, in Dispatch no. 4 to the Earl of Malmesbury, written from the Shire River: "... and Dr. Kirk, the botanist, found pepper growing wild …” Livingstone was probably referring to Capsicum annuum or Capsicum frutescens, red and green peppers, or mbiripiri in Shona. These small shrubs are natives of tropical America and would have been introduced by the Portuguese. However, it is just possible that he was referring to Piper nigrum, from which both black and white pepper are produced, and this too, would have arrived, via the Portuguese, from Brazil.
PISTlA: 14 February 1859, in an enclosure by Kirk to Livingstone’s Dispatch no. 13: "At the juncture of the Shire and Zambezi.... the contrast between the waters of the two rivers is very marked, that of the Shire being comparatively clear and bringing down an immense amount of Pistia or other aquatic plants...” Pistia stratiotes, the Nile cabbage or water lettuce, is a free-floating aquatic herb that can become a problem in rivers and dams.
PUMPKIN: 14 February 1859, in Kirk's enclosure to Dispatch no. 13: ".... Indian Hemp, ochro and pumpkins seemingly uncared for.” Kirk saw pumpkins in the Shire Valley where they had been introduced from Central America by the Portuguese or Arabs. They belong to the genus Cucurbita, originally from North America, whose 10-12 species have been cultivated since antiquity. Introduction into Central Africa was probably via the Portuguese.
RICE: 1 September 1861: "Rice is grown and one Mango tree was seen at our last bivouac.” This was written from Lake Malombe to the south of Lake Malawi before Livingstone reached the larger lake. Rice is Oryza sativa, which probably originated in Central Asia but has been cultivated since antiquity. It was probably introduced into Central and Southern Africa by the Arabs. The Shona name for rice is mupunga.
SESSAME: 10 October 1862, in a letter to Thomas Maclear written at the mouth of the Rovuma River: "Then people cultivate largely of the oil seed called Sessame or Saosame, which is largely exported from Mozambique and Zanzibar to make salad oil in France."
This plant was Sesamum indicum, which was probably introduced from India by the Arabs. It is known in Shona as runinga and in Ndebele as inkunzana enkulu.
SHUARE PALM: 20 September 1861: "Many trees and shuare palms, washed away, show that the Lake is eating westwards."
This was written during the exploration of Lake Malawi, and the palm Livingstone was referring to was Raphia farinifera, known by the vernacular chiwale in Malawi, and in Shona as muware. It has leaves up to 18 metres long, the largest in the plant kingdom. In Zimbabwe it occurs in three areas only, the Centenary district, the Nyamukwara Valley, and the "Corner", Chimanimani National Park.
STERCULIA: 27 June 1863: "Mpimbe has been beautiful from several gigantic Sterculia in nearly a circle."
Mpimbe was a deserted village on the Shire River at the time of Livingstone’s visit. The gigantic Sterculia would have been Sterculia appendiculata, which reaches heights of 40 metres in riverine and coastal forests. In Zimbabwe it occurs only in the extreme north¬east, and possibly many of our specimens have been submerged by Lake Cabora Bassa.
STRYCHNOS: 10 July 1861: "The Hornbills eat a species of Strychnos: sit with bills open.” Livingstone's observation was made on the Shire River at Chibisa.
The latest edition of Robert’s Birds of Southern Africa sheds no light on the matter, but presumably some of the larger hornbills would be capable of cracking open Strychnos fruit. The species eaten by the birds could have been any one of several. See also NUX VOMlCA.
SUGAR CANE: 10 September 1858, in Dispatch no. 111 to the Earl of Malmesbury: "Sugar is manufactured at Tette but, the process being rude, it is of inferior quality. And at plantations adjacent to Kilimane the cane grows almost wild."
17 December 1858, in Dispatch no. 12: "I was not aware that Sugar was manufactured by the natives till lately, but I bought six pots of it...” Kirk, too, noted sugar cane growing in the Shire Valley.
Sugar cane is Saccharum officinarum. It probably originated in tropical Asia and was imported into Mozambique by the Arabs and Portuguese. Today it is not found in the wild state in Asia. The Shona names for sugar cane are ipwa, ipwarungu, or nzimbe, and the Ndebele name is imfe.
SWEET POTATO: 14 February 1859, in Kirk’s enclosure to Dispatch no. 13: "Maize, yams, sweet potatoes... are grown in the gardens."
The sweet potato is Ipomoea batatas, a native of tropical America in ancient times and no longer known in the wild state. It is now grown throughout the tropics and was probably brought into Mozambique by the Portuguese or Arabs. Kirk's observation was made in the Shire Valley, but the sweet potato is well known throughout Zimbabwe where the Shona names are mubura, mudima, mumbambaira or kara, and the Ndebele names are imbambayilla (yellow tubers) or isibula (red tubers).
TAMARIND: 29 October 1958: "There are many tamarinds in the country."
8 June 1860: "On passing a large Tamarind tree people ran to it and made obscene gestures to it. This is done by the Portuguese too, who.... generally adopt the superstitions of the country."
The tamarind, Tamarindus indica, is one of the magnificent trees of the Zambezi Valley, and Livingstone would have soon become familiar with it. It reaches heights of 25 metres and diameters of one metre or more; the fruit pulp is edible, and it produces a hard, heavy, durable wood suitable for turnery and carving. The species was once thought to be a native of India, but it is now known to be indigenous to Africa as well as the Far East, and it was known in Egypt in the fourth century BC. The superstitions surrounding the species in Mozambique in Livingstone's time are not recorded in more recent literature. The Shona and Tonga name for the tree is musika.
TEAK: 13 August 1859: "Got a piece of teak which is called by the Makololo Moramane. It burns well."
This was written on the lower Zambezi, a little upstream from the confluence of the Shire and well outside the range of the Zambezi teak, Baikiaea plurijuga. It is possible that Livingstone was using another name for a tree he had previously called mosany, Erythrophleum africanum, but the closest vernacular is the Lozi mulamane Combretum fragrans (formerly Combretum ternifolium). However, this is not a satisfactory interpretation because the species does not produce a timber that could be called "teak".
TOBACCO: 14 February 1859, in Kirk's enclosure to Dispatch no. 13 ".... cotton and sugar cane, tobacco and ginger are grown in the gardens."
Tobacco was recorded from the Shire Valley, and the crop(s) Kirk saw could have been Nicotiana rustica – Shona chikwarimba or fodya, Ndebele igwayi – which is grown by subsistence farmers for snuff, or Nicotiana tabacum (same vernacular names), which is cultivated by commercial and subsistence farmers for smoking leaf. A third, though unlikely, species might have been Nicotiana glauca, tree tobacco, which was originally introduced as an ornamental but has escaped cultivation. All three species probably originated in South America and the first two have been cultivated since antiquity. Introduction into Mozambique was probably via the Portuguese, possibly the Arabs, and from Mozambique the species would have spread into the rest of Central Africa.
TREE FERN: 18 December 1862, in a letter to his daughter Agnes Livingstone:
"There are tree ferns 20 feet high..."
Livingstone's letter was written from Shupanga on the Zambezi, but the passage quoted above was about his visit to Johanna Island (now under a different name) in the Comoros during his return journey to the Zambezi from the Rovuma River. The tree ferns he saw could have belonged to one or more of the genera Alsophila, Cyathea, Dicksonia, or Hemitelia.
WATER LILY: 14 February 1859, in Kirk's enclosure to Dispatch no. 13, "There are also lagoons in which the people find the water lily root which they roast and eat."
This observation was made on the Shire and it is possible that the "water lily" was Colocasia esculenta, known in Shona as mudhumbe, an Asian plant that has become naturalized along streams and rivers in some parts of Central Africa. This is not strictly a water lily for it grows on the stream banks where it is cultivated for its edible, starchy, tuberous rhizomes.
Another possibility is Nymphaea caerulea, a floating water lily with tuberous rhizomes that are sometimes eaten. The Shona names for this plant are hapa or hobvwe, and the Ndebele names are ilalala or amaleboemfula.
YAM: 14 February 1859, in Kirk's enclosure to Dispatch no. 13: "Maize, yams, sweet potatoes are grown in the gardens."
The yams Kirk noted under cultivation in the Shire Valley are assumed to have been one or more of the tropical American species of Dioscorea, which have been cultivated from ancient times for their edible, starchy tubers or rhizomes. There are also several Central African species of Dioscorea, at least two of which occur in Zimbabwe. These are Dioscorea bulbifera (Shone idiya) and Dioscorea schimperana (Shona mutendeni) both climbers with edible tubers but not known to be cultivated.
MOSIBE: This tree has been left to the end because it is not mentioned in Livingstone's Zambezi journals, although it is recorded in the "Narrative" by David and Charles Livingston., published in 1865.
Mosibe is better known in Zimbabwe as umtshibi (Ndebele), or Guibourtia coleosperma, an assoc¬iate of Zambezi teak and one of the great trees of the Kalahari sand forests of north-western Matabeleland. There are two fine specimens of this tree 70km from Bulawayo on the Victoria Falls road, and another one halfway along the 5km stretch of road leading to Lupane.
Also not mentioned in his Zambezi journals, but recorded elsewhere, on his second visit to the Victoria Falls in 1860 Livingston planted some "living orange trees, cashew nuts and coffee seeds" on what is generally known as Livingstone Island or Garden Island as he called it. Nothing survives of this planting. It was on this island too, at the time of his first sighting of the Falls in 1855, that Livingstone carved his initials on a tree “the only instance in which I indulged in this piece of vanity.” Photographs of this tree, taken in 1905, suggest that it was Diospyros mespiliformis, but we cannot be absolutely positive about it. Contrary to some fondly held beliefs, myths, and fables Livingstone did not carve his initials on the Big Tree at Victoria Falls, a Baobab, and in all probability he never even saw it.
Lyn Mullin

We thank Lyn for this most informative and interesting narrative which we have enjoyed over the past few months.

The Tree Society’s e-mail address is
petra@mango.zw (Ruth Evans)