Saturday August 5th: National Botanic Gardens Walk. Meet in the car park for an 08.30 start. Please note the new time, if it does not work we can always revert to our later time. The gardens are looking lovely and there should be some trees coming into flower, others flushing. A magic time of year with some warmth in the air.
Sunday August 20th: Outing to Twala Trust Animal Sanctuary: where there is some lovely woodland, a pretty picnic spot and lots of happy rescued animals to enjoy. There is a $10 per person entry fee that goes to such a worthwhile project. One can pay by Eco cash at the gate, or if it is convenient to pay at the 2nd Street 24 hour Vet the day before or on the day, one can pay by swipe machine there and bring the receipt.
DIRECTIONS: For those who would like to share transport, meet at Mukuvisi Woodlands to depart at 09.15. Meet at Twala at 10.00. Bring a chair, picnic, hat etc.
Saturday August 26th: VENUE TO BE ADVISED
OUTING TO BRYDEN COUNTRY SCHOOL 16TH JULY 2917
On a lovely chilly morning we made our way to Bryden Country School, just before Chegutu. A long drive but it was well worth it.
Howard M., the Headmaster, and his lovely wife Janet very kindly hosted us. Howard took time out of his busy schedule to show us the lovely woodland around the school and guide us down to the Mapfure River. Janet laid on a most welcome tea when we got back from our walk along the Mapfure. Dave White from Lomagundi College also joined us.
We had a fair turn out, with Tony as the Uber Grouper, Graham, Isla, Mary, Bilal, Dawn, Alex, Ian Riddell, and Vernon and Marilyn
Our first stop was the Mapfure River about a kilometre from the homestead. We had a happy walk along the bank and it was good to see the river with so much water for this time of year. Species seen here were as follows:
Acacia galpinii; Acacia polyacantha; Albizia amara; Azanza garckeana; Catunaregam taylorii; Combretum erythrophyllum – the River Combretum with small winged fruit; Croton megalobotrys; Dichrostachys cinerea; Diospyros lycioides; Diplorhynchus condylocarpon; Euclea divinorum; Euclea natalensis; Ficus burkei; Flacourtia indica; Gardenia sp.; Grewia monticola; Gymnosporia senegalensis; Kigelia africana; Ochna schweinfurthiana; Peltophorum africanum; Philenoptera violacea Rain Tree; Ricinus communis – Castor Oil plant; Searsia quartiniana –ex Rhus; Terminalia sericea; Vangueria randii; Vernonia sp.; Ziziphus mucronata
We then returned to the homestead and, after a very welcome cup of tea, walked through the woodland behind the Headmaster’s residence, species seen on this walk included:
Acacia amythethophylla; Acacia goetzei; Acacia sieberiana; Bauhinia petersiana; Berchemia discolor – Bird Plum; Brachystegia boehmii; Capparis tomentosa; Cassia abbreviata; Colophospermum mopane; Combretum adenogonium – Four-leaved Combretum; Combretum collinum; Combretum hereroense – Mouse-eared Combretum; Combretum imberbe; Diospyros mespiliformis; Diplorhynchus condylocarpon; Euclea natalensis; Ficus lutea; Flacourtia indica; Flueggea virosa – Snowberry; Friesodielsia obovata; Julbernardia globiflora; Khaya anthotheca; Lannea discolor; Ochna puberula; Ochna schweinfurthiana; Ormocarpum kirkii; Piliostigma thonningii; Pseudolachnostylis maprouneifolia; Sclerocarya birrea – Marula; Senna singueana; Steganotaenia araliacea – Carrot Tree; Terminalia stenostachya; Turraea nilotica; Ziziphus mucronata.
By this time we were ready for our picnic lunch, which we enjoyed in Howard and Janet’s beautiful garden. Very many thanks to Howard and Janet for making this a very special outing.
OUTING TO MUKUVISI WOODLANDS, BLATHERWICK GATE ENTRANCE 22ND JULY 2016
Only four of us – Tony, Jan, Bilal and Mary – ventured out for this occasion, but the scarcity of numbers did not detract from a good afternoon in this lovely part of the Woodlands. Whilst we sat at the picnic site, hoping that someone else might arrive, we recorded the trees around us from where we sat. What an amazing diversity of species there is in this area and many went unrecorded. We started with a short walk along the “green” route, not venturing off the path and had some good discussion. We returned to the picnic site for a drink and a snack and went home well satisfied with our afternoon in the woodland and saddened that we had not been able to share it with more members.
A list of some of the trees we saw is as follows:
Erythrina abyssinica – Lucky Bean tree, flowering and identified by its serrated, upturned flowers.
Combretum molle – Velvet Bush Willow – Meg’s ‘Wish’ tree; Strychnos spinosa – Sweet Monkey Orange; Terminalia sericea – Silver Cluster Leaf; Vitex payos – Chocolate Berry; Julbernardia globiflora – Munondo; Pseudolachnostylis maprouneifolia – Duiker Berry; Brachystegia spiciformis – Musasa; Ochna puberula – Granite Ochna; Vangueria infausta – False Medlar; Commiphora africana – Poison grub Corkwood with thorns, smooth bark; Senna singueana – Winter Cassia; Diospyros lycioides – Red Star Apple; Pterocarpus rotundifolius – Round-leafed Bloodwood; Pterocarpus angolensis – Mukwa; Pavetta schumanniana – Poison Pavetta; Flacourtia indica – Governor’s Plum; Grewia decemovulata –Miombo Dwarf Grewia; Euclea crispa – Blue-leafed Euclea; Ochna schweinfurthiana – Brick Red Ochna; Swartzia madagascariensis – Snake Bean; Gymnosporia senegalensis – Confetti Bush; Albizia antunesiana – Purple-leafed Albizia; Acacia sieberiana – Flat-topped Thorn, Paper-barked Thorn; Burkea africana – False Ash, Red Syringa – with its red velvety tips; Acacia karroo – Sweet Thorn, Mimosa Thorn; Parinari curatellifolia – Mobola; Peltophorum africanum – African or Weeping Wattle; Acacia polyacantha – Hook Thorn; Acacia rehmanniana – Silky Thorn; Rhoicissus tridentata – Bushman’s Grape; Rhus longipes – Large-leafed Rhus; Allophylus africanus – African False Rhus; Clerodendrum eriophyllum – Hairy Tinderwood; Lannea discolor – Live Long tree; Syzygium cordatum – Waterberry; Azanza garckeana – Snot Apple; Gymnosporia buxifolia– Common Spike Thorn; Faurea saligna – African Beech; Psorospermum febrifugum– Christmas Berry.
The two articles below came from Tree Life 75, May 1986, following a Tree Society visit to the Great Dyke, when they were joined by members of the Kirk Society from the Dept. Biological Sciences at UZ. The first, by Phil Haxen, contains an interesting information about Sir John Kirk GCMG, KCB, FRS,MD. This is followed by Meg’s account of the day.
MPONDAMINGA ON THE DYKE: SUNDAY APRIL 20TH 1986
Of the 36 people who arrived at the Monomatapa Car Park for the 0830 hours start, not one suggested that we cancel the trip because of the inclement weather. We left in the rain and we returned in the rain and it rained during the day, but as there were no complaints, I am sure everyone enjoyed the day as much as I did. It was dry when we arrived at Mpondaminga.
While the queue for the loo diminished, we wandered around the garden admiring the trees, the view and the aloes, trying to imagine what they would look like in flower and whether their names and the pronunciation thereof were really important. There were a couple of Hymenodictyon floribundum, the Firebush, in magnificent red leaf. This is the time of year when they turn red and drop their leaves in a short space of time and so we were there just at the right time. We also saw Kirkia acuminata which gave me the appropriate moment to welcome the members of the Kirk Society to the outing – this is a Society of budding botanists at the University – and we wondered when the name Kirk became a household name amongst botanists.
Sir John Kirk, GCMG, KCB,FRS,MD (to give him his full title) was born near Dundee in 1832 and as one of the principal hobbies of his father was botany, his interest in plants must have developed at an early age. This continued and while he was a student he became a fellow of the Edinburgh Botanical Society. He graduated as a medical doctor in 1854 and in 1855 sailed for Crimea. While there, first at Scutori and later in the Dardanelles, he found time off from his medicine to collect plants on Mt. Olympus and Mt. Ida. Following this, he was appointed as Naturalist to Livingstone’s Second Expedition, of which he was a member for 5 years. They left England on March 10th 1858. His diaries consisted of 10 note books filled with careful pencil-written notes and sketches and his collection of plants was extensive. In March 1860 one member of the expedition returned to Britain with four cases of Kirk’s specimens consigned to Sir William Hooker. In 1883 Sir William’s son, Sir Joseph Hooker who had succeeded his father as Director of Kew, received a letter from Portsmouth Dock saying that 4 cases of specimens had been deposited there in 1870 and please would he take steps to have them removed. What happened between 1860 and 1870 only the cases know.
In November 1860 when shooting the rapids at Kebrabasa, Kirk’s canoe was dashed against the rocks and he lost many of his specimens, 8 volumes of notes and all his equipment. The specimens which he had collected at the Victoria Falls were fortunately in another canoe. Kirk left the expedition in May 1863 and returned to London. At Kew he deposited a large collection of plant specimens accompanied by a valuable collection of field drawings from the Zambezi Valley; an area which at that time was rich in undescribed species. He was also one of the earliest photographers and amongst the first to photograph the vegetation of the Zambezi region.
I thought it would be interesting to recall some of the plants which have been named after John Kirk. The genus Kirkia was described in the Flora of Tropical Africa by Oliver in 1868 and so was Kirkia acuminata, both from specimens collected by Kirk at Kupata and Sene in Mozambique, probably in October/November 1858. Another species described by Oliver, this time in 1871, is Acacia kirkii, Flood Plain Acacia, a species of the Zambezi Valley and having pods with a wart-like protuberance over each seed. This was collected by Kirk in the Batoka country in the Southern Province of Zambia in 1860.
Cleistochlamys kirkii, a member of the ANNONACEAE family, is a lowveld species and was originally called Popwia kirkii by Bentham in 1862; however Oliver in 1865 decided that it belonged to the genus Cleistochlamys. Kirk had collected the material from Mozambique, opposite Sena at the foot of Mt. Murrombala.
Type specimens of Maerua kirkii, Large Flowered Maerua, are from Cape Mclear on Lake Malawi and Mitonda on the Upper Shire River and were collected by Kirk in 1861. This was originally called Capparis kirkii in 1868 by Oliver and updated by Frank White in 1958.
In 1877 Spencer Moore of the British Museum described Ormocarpum kirkii, the Caterpillar Pod, with which we are all familiar, the type specimen coming from the River Tola in the Somali Republic. Some other “kirkii’s” which Kirk collected are Psychotria kirkii, the fairly widespread shrub often seen in granite in the watershed woodlands; Rhus kirkii, a suffrutex found in open Brachystegia woodlands, but discovered by Kirk near the Victoria Falls; Dombeya kirkii, River Dombeya growing at lower altitudes which was first collected by Kirk at the Mupata Gorge on the Zambezi River above Cabora Bassa – spelt Kebrabassa, in his records – about 1860. Diospyros kirkii was collected and described by Hiern in 1873. All those species have maintained their names as being the earliest collected and described.
Kirk collected a Cussonia at Mt. Morrumbala which was named Cussonia kirkii. Unfortunately, it was subsequently discovered that the species had been described earlier and named C. arborea. This of course is our familiar Octopus Cabbage tree. And the most recent casualty is Ficus kirkii, a giant strangler of evergreen forests, which gives way to the name F. scassellatii.
Kirk subsequently spent 20 years in Zanzibar as a medical doctor, Vice Consul and ultimately the Consul General and is famous for the part he played in suppressing the slave trade. He was knighted in 1890. He retired to England and died in 1922.
As a footnote, “Kirkia” the Journal of Botany of Zimbabwe, together with Flora Zambesiaca, have been my sources of information.
We had a good day with lots of interesting species. Olax obtusifolia was there, but Kim was not and so we had no-one to persuade us that when the leaf was crushed and the cells broken, cyanide was released into the air. Ficus nigro-punctata was an exciting find. When we last saw this species at “Kujawi”, Gadzema, it was growing in the fork of a tree and the roots had not yet reached the ground. Then it was suggested that as this was such a rare tree, many of us were unlikely to see it again. Punctate comes from the latin punctum, point, and to quote from the dictionary of Scientific Terms, means “dotted”, having a surface covered with small holes or dots; having a dot-like appearance.” Returning to the write up of the specimen we saw at Gadzema, Kim said that the trunk was not black, nigro, and neither was the trunk of this tree at Mpondamina. It was about 10cm in diameter and was growing next to and strangling a Vitex payos. However, we did look for black dots in the leaves and through a lens we could see little dots all over, although these dots were not black. The leaves put in a plastic bag, identified at the Herbarium and now being looked at again, still have little dots when held against the light and examined with a lens, but the upper surface of the leaves have now become black, perhaps that explains the name and we could translate nigro-punctata as “leaves which turn black and are covered with little dots”?
We then looked at Ozoroa insignis, Tarberry and Raisin-berry. This tree was fruiting and we were able to see the kidney shaped fruit covered with black wrinkled skin and looking for all the world like a raisin or currant. Tasting it offered nothing in the way of nourishment and little in the way of flavour. In fact it left the mouth slightly dry. We then climbed through the fence and came face to face with a Combretum zeyheri, Large Fruited Combretum with unmistakably large green shiny fruit and interesting galls 3-4mm wide, 30-40mm long about 20 in all along a little stalk.
We then moved to Ozoroa longipetiolata with, as the name suggests, long petioles. The drooping foliage is silvery grey and the stems cinnamon coloured, giving the tree a willow like appearance. These trees only grow along the chrome hills of the Dyke and so are of great interest. The first one we looked at was in fruit, more round than kidney shaped, but with the same wrinkled skin and disappointing flavour.
With quite a pleasant flavour, if one was fortunate enough to discover a ripe one, was the fruit of Rhoicissus revoilii. This is a member of the grape family VITACEAE, and had a trunk and branches very strongly resembling a grapevine. The leaves are trifoliolate and the under surface covered with dense rusty hairs which are quite beautiful when caught in the right light.
Eventually we reached the river where we saw Diospyros natalensis, its tiny leaves festooned with the debris of a recent flood. A Myrica serrata was climbed in order to acquire leaves for identification. This is known as the Waxberry and the fruit and branches immersed in boiling water give off a true fat, rich in fatty acids. The leaves are alternate and serrated. The serration or scallops round the margin are somewhat reminiscent of Nuxia oppositifolia, which we also found. As the name suggests, that has opposite leaves.
By this time the rain was threatening and the sensible made their way up to the house. The less sensible lingered a little too long and got wet. However, I must mention that the presence of Rapanea melanophloeos has been confirmed.
We had lunch on the verandah, in the house and in the bus, while the rain teemed down. It was well after 1400 hours when it eventually eased off and we boarded the bus and went off to explore the small patch of Swamp Forest which was supposed to have been used in the filming of King Solomon’s Mines. This may well have accounted for the excellent state of the road to that spot.
The forest consisted of big trees which we easily identified as Syzygium and which I am assured is S. guineense, although they had long narrow leaves and a small petiole. This is the form that S. quineense takes when in swamp forest conditions and the possibility of it being a hybrid with S. cordatum has not been ruled out. Of the 14 leaves on the twig I brought back one appeared to have a tendency to exhibit a slight cordate base, and many more leaves should have been examined. Other species in the forest were Maesa lanceolata, Nuxia oppositifolia and Phoenix reclinata.
We returned via the Mutoroshanga Pass and stopped to look, through binoculars I might add, at Aloe ortholopha and Euphorbia wildii, both of which are also endemic to the Dyke.
Thanks to the Perry family for allowing us to invade their house and for sharing the trees with us.
-Meg Coates Palgrave
WHY DO OLIVES NOT FRUIT IN THE AMAZON?
I wonder how many of us, since we packed away our geography school-books for the last time, have reflected on what life on this planet would be like if its axis of rotation were not tilted at 23.5o to its plane of orbit around the sun? That singular conjunction of the arts and the sciences, the miracle we call the seasons, would not exist. Every day of the year would be identical. May, October, February, the sun’s only journey would be daily from East to West, none of the six-monthly migration North, then back again.
The sun would cross the meridian in the exact same position year-round, depending on the latitude, directly overhead if you were on the Equator, at 760 above the horizon in Lilongwe, 560 in Sydney, 390 in London, while at the poles the sun would circle permanently along the horizon. We have that tilt to thank that this is the scenario on planet earth only twice a year, at the time of the March and September equinoxes.
What would have been the effect on biological diversity on earth if the monochrome decline in temperature experienced as one moved from the tropics through the sub-tropics and temperate regions to the Arctic, had held sway permanently? It is doubtful we would know any of the culinary and aesthetic delights we today take for granted – grapes, olives, pomegranates, dates, stone fruit, ericas and magnolias. Not that soya, millet and msasas are in any way inferior, of course.
It is almost as if divine consciousness made a plan to compensate for the lower solar intensity in the sub-tropics resulting from the fact that the sun is, by definition, never directly overhead at latitudes above 23.50. That tilt gives Sydney at 340S 14½ hours daylight in December. Dar es Salaam, much closer to the Equator, never experiences more than about 12½. Pay-back time comes in June of course, when Sydney has just 9½ hours, coinciding with the time the sun reaches an elevation in the sky of just 32.50 at mid-day (900 less 23.50 less its latitude).
This results in the curiosity that while Dar es Salaam has 326 days in the year when its maximum temperature exceeds 300 and Sydney only 44, Sydney’s mercury hits 400 most years. Dar’s ceiling is pretty well 350. On the other hand, Dar’s minimum dropped below 180 on just one day throughout 2016, while Sydney’s didn’t reach 160 for half the year.
It seems to me that the richest diversity of living organisms has evolved in the Amazon simply because the world’s largest rain forest straddling the Equator offers middle-of-the-road fare, the avoidance of extremes of heat and cold, and rain falls when it is supposed to – in summer! The extreme signals from the sub-tropics on the other hand entice the eccentric niche-players with more specialised fancies. Some years back I heard an ecologist from Western Australia saying that some ecosystems there came a close second to the fynbos of the Western Cape in breaking records in terms of species concentration in a comparatively small area of the sub-tropics.
My earliest experience of month-on-month sustained temperatures in the 40s was in the lead-up to the mechanised harvest of black and yellow dates (Phoenix dactylifera) in which I participated from August to October 1983. This was 100m below sea level in the Jordan Valley, far enough North (300) that the Southern Cross was never visible. The olive yields (Olea europaea) also depended on unrelenting long hours of summer sunshine, the kind of rainfall that NGOs and governments here would declare a disaster (<300mm), and not forgetting some (not too much) winter chill. I still have to be convinced that, until global warming really kicks in, there are significant parts of Southern Africa North of the Tropic of Capricorn where the winters are severe or wet enough and the hours of sunshine in summer long enough to produce an economic return on olives, peaches, grapes or even wheat, without some form of hidden subsidy.
Of course some of the most dramatic climatic and habitat transitions occur within a few hundred metres, without crossing a single line of latitude. During my daily ascent of the Bvumba Mountains from 2002 to 2006, I always marvelled at the suddenness of the transition from Brachystegia woodland to evergreen forest just above the White Horse Inn turnoff. Wild date palm (Phoenix reclinata) and the Sycamore Fig (Ficus sycomorus), normally thought of as thriving under wet conditions, suddenly go AWOL above about 1350m. It got me wondering whether it was the pollination vectors (birds and wasps) that have an aversion to mist-belt conditions. Or was F. sycomorus in particular, so dominant in the Mutare Valley where temperatures can reach 380 (10 years ago, now probably more), suddenly finding it was not getting its preferred daily dose of hot sunshine?
Then again, the Raffia Palm does splendidly in the Bvumba Botanic Gardens, clearly outside its normal range, but in a frost-free zone. If global warming of (say) 1.00 is already manifesting itself as a rise of 40 in high temperatures in some parts of the world, and a drop in lows of 30 elsewhere, and if we are to avoid the general impoverishment of species, is it time people like me became slightly less sniffy about introducing species from other zones within the same continent? Should we start by giving thought to the intelligent selection of species of Acacia other than A. abyssinica without the potential to become invasive and thereby upset the biological and aesthetic integrity of the Upper Bvumba? Anyone who has explored Imbeza Valley since 2000 will know how the remaining and ageing stands of A. abyssinica there are under threat.
Perhaps after all it is not that fanciful to be planning a future for olive trees around Leopard Rock! Or at any rate a few hundred metres lower in Burma Valley, in anticipation of the day when silted rivers and falling water tables put a question mark over the future of bananas there. If the earliest life forms emerged in Africa, it is fitting that this continent provides the solutions to redeem some of the damage we humans have been inflicting on ourselves.
The accompanying table compares daily temperatures of a tropical city with those of a sub-tropical one, within five different altitude zones from coastal to 1624 m.a.s.l. The two trends observed with increasing distance from the Equator are falling mean annual temperatures, but increasing seasonal swings. Most striking is sub-tropical Ahwaz, in Iran’s Shatt-al-Arab at 310 N., 160km away from the moderating influence of the Persian Gulf, the only one of my city selections where the maximum in 2016 reached 500C (twice). But it is only in the 400C+ range that Ahwaz retains its ascendancy, 139 days against tropical Khartoum’s 107. Once you move below 390C, the situation reverses. Sudan experiences 261 days of temperatures above or equal to 350C while the sub-tropical deserts of Mesopotamia endure a mere 188.
Some tens of millennia ago, the more restless among human-kind that migrated toward the poles became paler skinned. Plants, on the other hand, considerably further back in time, had curled up their toes in disgust at the thought of leaving their equable Equatorial comfort-zones for the, by turns, torrid and frigid sub-tropics. This treasure-trove of diverse species included the original Acacias. So free rein was found in the parallels of latitude between 23.50 and about 400 by many of the delightful oddities of the plant kingdom, from olives to a vast array of wattle species, for which the Australians are trying to snaffle the exclusive use of the generic name “Acacia” from right under Africans’ noses!
The unanswered question: why is it that invasive species we in Southern Africa regard with a mixture of such loathing and reluctant admiration, such as Acacia melanoxylon, A. mearnsii and the Himalayan cherry (Prunus cerasoides), did not evolve here in the first place? Could it be that the relatively hostile and therefore evolutionarily un-crowded latitudes above 23.50 served as an incubator for aeons to perfect those characteristics that appear to give them such unfair advantage over native species today when transplanted here?