Expedition no. 34: Tree Society visit to Outward Bound, Chimanimani: 13 Apr 2001-18 Apr 2001

CHIMANIMANI: OUTWARD BOUND:
13-18 APRIL 2001

This long, combined Easter and Independence weekend drew a larger than usual number (c. 24) of members to Outward Bound in the Chimanimani mountains.

FRIDAY 13 APRIL (Good Friday)

The journey down (and back) took on an epic flavour as all the members planned and schemed to ensure that they would have sufficient fuel. The Hydes and Harwins decided that the landcruiser, with its large tanks, could just make it there and back without filling up if we did nothing else. So, early on Friday morning, we piled cases high on the roof rack and newspapers for plants into the car. Then we found corners in the pint pot for the actual bodies.

Along the road we stopped at every station for fuel. Nothing was found until Rusape and then only petrol. We consoled ourselves that most members would probably have petrol vehicles.

It has been nearly 10 years since the Society visited Outward Bound in August 1991 and in many ways it was broadly as I remembered it. The general layout of the buildings is the same but some of the surrounding areas (e.g. the walk to Tessa's Pool) had become more scrub-like whereas I remember them as grassland. I had forgotten how very tall and imposing the surrounding bare mountains are.

SATURDAY 14 APRIL

The general vegetation on the hills around Outward Bound consists of Brachystegia and Uapaca woodland (although the actual species seen were not exactly the same as they would have been around, say, Harare). The rainfall is high and the altitude is quite low (c.1100 m) and these two facts characterise a lot of the vegetation seen. We were there after what was said to have been an abnormally wet season and certainly I have never seen such spectacular long-pendulous grey-green curtains of lichen which were very plentiful on the trees. Epiphytes such as ferns, orchids and peperomias were also common.

Other habitats included some evergreen forest around Tessa's Pool, presumably riverine, which was of great interest. Just below Tessa's Pool is a wide vlei, which is not a very common habitat in the Eastern Districts. There were also areas of scrub and grassland, containing such species as bracken, Smilax and small shrubs. A further factor in understanding the flora is that species endemic to the Chimanimani mountains begin c.100 metres east of Outward Bound.

The first morning was a local walk in which, much to the amusement of the non-botanists, we took 3 hours to walk to Tessa's Pool. In fact, this wasn't really long enough as we didn't have quite enough time to study the trees around Tessa's Pool in sufficient detail!

The first part took us through scrubby vegetation with species not unlike those we see in savannah conditions - Dodonaea angustifolia (Sand olive), Psorospermum febrifugum (Christmas berry), Strychnos spinosa. Also present was the common, stout, coarse, tussocky grass which is so common in the Eastern Highlands, namely Eragrostis acraea. In addition to eastern Zimbabwe, it also occurs (a remarkable record!) on one of the outliers, namely what used to be called Besna Kobila in the E Matopos and also outside Zimbabwe in the E Transvaal. Also present was the prickly climber, Smilax kraussiana, which so often makes walking in the eastern districts nothing to smile about. The plant, perhaps surprisingly, is a monocotyledon and is somewhat related to the lily family. Modern opinion appears to put in the Smilacaceae or, sometimes the Philesiaceae. It has flowers in umbels and broad leaves.

On beginning to descend slowly the path to Tessa's Pool we entered some open Brachystegia woodland. We found this genus rather puzzling and I am not sure we really understood everything we were seeing. Certainly, there was Brachystegia spiciformis (with more leaflets than usual as is often the case in the east). We also found Brachystegia microphylla (Small-leaved brachystegia) with its very large number of leaflets (25-55 pairs per Coates Palgrave) and there were also numerous intermediates with intermediate numbers of leaflets. However, I must admit to some confusion as to whether Brachystegia glaucescens occurred and how precisely it differed from microphylla and the various spiciformis/ microphylla intermediates.

Also in the scrub was Monotes engleri (Pink-fruited monotes). This is the slightly rarer one of the pair of woodland monotes and has strongly discolorous leaves which are green above and greyish beneath. A plant we don't often see is Annona senegalensis (Wild custard-apple). This is usually a shrub and has large slightly greyish leaves, which smell aromatic when crushed. It is very much a plant of lower altitudes, usually in high rainfall areas.

As we approached Tessa' Pool, some of the very exciting species, typical of mid-lower altitude forest, appeared. For a start, a very large Newtonia buchananii (Forest newtonia) overhangs the pool. Shrubs of Englerophytum magalismontanum (Stem fruit) occur in the understorey - this is of course a species of much higher altitudes as well.

One of the interesting features of the Zimbabwean flora is how within a genus there are species which occur in savannah woodland and often one which occurs in forests. The latter usually has glossy, evergreen leaves with a drip-tip. Two examples of this feature were seen at Tessa's Pool.

In the genus Garcinia, we have the forest species, Garcinia kingaensis (Northern forest Garcinia). This has dark green, thick leaves with a prominent apex. The two savannah species are the highveld Garcinia buchananii (Granite garcinia) and Garcinia livingstonei (African mangosteen). All three species have yellow latex, best seen by folding a leaf transversely so that it cracks, whereupon yellow globules appear along the crack. Incidentally, Garcinia livingstonei differs in having leaves in whorls of 3, whereas the other two have mainly paired leaves.

The second example was Artabotrys monteiroae (Red hook-berry), which is a glossy-leaved equivalent of the more familiar, riverine Artabotrys brachypetalus. Both species are climbers and both have the strange-shaped hooks which are formed from the stalks of the inflorescence.

Further riverine species seen included Breonadia salicina (Matumi). A quick check was made that it produced no milk in order to confirm it was not Rauvolfia caffra, although spherical inflorescences were also seen which make it even more certain. Also a rather unusual shrub in the Apocynaceae, namely Mascarenhasia arboresecens. The latter has milky juice and rather prominent paired pods.

The hardier members swam in the refreshing chill of Tessa's pool before returning to Outward Bound for a relaxing afternoon. The weather on this day was practically perfect with nearly continuous sun in a striking clear atmosphere with startlingly good visibility.

In the afternoon, a smaller party walked a short way to the east of Outward Bound and soon found ourselves in the country of endemics. We saw, as in 1991, a large species ofAeschynomene, probably grandistipulata. It is a legume with orange-yellow flowers, slightly glaucous foliage with large leaflets and, as the name suggests, large stipules. Also seen was the Shell-leaf, Hemizygia flabellifolia, another endemic to the Chimanimani mountains. This has recently been renamed Syncolostemon flabellifolius.

The evening was spent with a hilarious drawing game suggested by Eva. It was a sort of artistic version of whispering a message down a long line of people and finding something different emerge at the end. Mark Hyde

SUNDAY 15 APRIL

The plan for this day was to walk back out along the road to Outward Bound until we came to the Haroni River, have lunch and then return along the river. This is pretty much how it turned out, although again staff at Outward Bound were astounded at how long it took us to get to the gate. Once again, the sun shone brilliantly through the azure skies.

The first part of the walk took us though scrub with isolated larger trees and occasionally stands of evergreen, riverine trees as the road crossed various rivers. The three species carefully learnt by Linda the day before (Harungana madagascariensis, the Praying hands bush, Toddalia asiatica with its "naartje berries" and the large-leaved Annona senegalensis) presented themselves for revision.

The shrubs seen included Otholobium foliosum, which is a legume with 3-foliolate leaves which are gland-dotted and purple flowers. It is a species of high rainfall areas, occurring mainly in the eastern highlands, although there is an isolated and rather strange record from Devedzo Hills near Rusape. A visit is needed one day to check on that locality.

Here also were the purple flowers and golden fruits of the Buffalo Bean (Mucuna sp.). A shrub which is rather local on rocky hills and in high rainfall areas along the watershed is Solanecio mannii (Crassocephalum mannii - the Canary-creeper tree); this has leaves clustered near the stem apices with numerous leaf scars and (at the right time of year) strongly unpleasant-smelling flowers.

In the shade at one point was Peddiea africana, with its glossy leaves and green (sometimes tinged with red) flowers in small umbels. The identity of the Peddiea can be confirmed by breaking off a piece. This never breaks cleanly but strips off down the branch. Its family is Thymelaeaceae, a smallish family in Zimbabwe, which includes such cultivated species as Daphne, which Peddiea clearly resembles.

Where the road crossed the Hadange River, a different flora came in, composed of evergreen woody species. We puzzled over a medium-sized tree with glossy pinnate leaves and spherical fruits. The latter had striking red seeds with a yellow aril at the base. Eventually, we decided it was Bersama swynnertonii (Purple bersama). Also by the stream were more specimens of Breonadia, the palm Phoenix reclinata, Schefflera umbellifera (Forest false cabbage tree), a Syzygium and the distinctive hooks of Artabotrys monteiroae. In the trees climbed a species ofLandolphia with its spherical fruits.

The road then took us through more open bush, a lot of it somewhat disturbed by man and mombes, which included the red-flowered Bauhinia galpinii, the climbing Mussaenda arcuatawith its yellow flowers, a climbing Clematis, which is unidentified as yet, and Embelia schimperi, also a climber which, like Rapanea in the same family, has glandular translucent streaks in its leaves. Various weeds with a low altitude component were present - specificallySenna occidentalis (Coffee senna).

Finally, we arrived at the Haroni and met up with Pippa Browne who had kindly backpacked our lunch to us (taking about 15 minutes to do what had taken us 3 hours). After lunch we returned along the Haroni. There was some excitement here as we removed our shoes and socks in order to cross the slightly swollen Hadange river, but all too soon we were back at Outward Bound.

Mark Hyde & Linda Hyde

MONDAY 16

HADANGE VALLEY

The third day of our visit dawned with the mountains shrouded in mist and the weather outlook uncertain. We had a hearty breakfast of oatmeal porridge and fried egg and bacon, prepared our picnic lunch in the kitchen, and set off up the Hadange Valley with Phillipa to show us the way. The Hadange is a tributary of the Haroni that runs down from the mountains to the south of the Centre. William, Eva and three of the boys left before us with the intention of climbing to the top of the mountains. We were joined this day by the Buttress and Jackson parties from Marondera.

The first part of the walk led through mixed woodland and over a rocky ridge dotted with stunted trees festooned with old man's beard lichen over 1 m long. Erica spp. grew in between the trees, and the stony ground was carpeted with mosses, while the rocks were spattered with orange and white lichens. Mark showed us some very unusual plants. Aeschynomene grandistipulata is a shrub endemic to the area and common around the Centre. It has pale green, fleshy, pinnate leaves, with the leaflets set at an angle to the plane of the rhachis, and takes its specific name from the leaf-shaped stipules that are bigger than the leaflets themselves. The flowers are orange and pea-like. It was too early for the fruit, which in this genus is said to resemble a row of false teeth. Rhipsalis baccifera, Zimbabwe's only indigenous species of cactus, was growing in a tree at a fork in the path. It has long, branching, green stems, far removed from what one would imagine a cactus to be. Two rather insignificant Chimanimani-endemic herbs seen were a subspecies of Otiophora inyangana, with flattened ericoid leaves and small, pale pink, star-shaped flowers, and Thesium chimanimaniensis, with thin, branching, green stems.

We descended the other side of the ridge and crossed the Hadange River on a narrow wooden suspension bridge. The path led through grassland among small clumps of trees, including an unidentified species of Indigofera with red flowers rising above its spreading branches. Then we climbed on a slippery path into the National Park towards the mountains through tall Uapaca kirkiana forest. Harungana madagascariensis, easily recognisable by its "praying hands" terminal leaflets and its orange latex, and Maesa lanceolata, with its panicles of pale yellow flowers, made up the understory. Orchids grew in almost every tree, and on the ground we found blue-flowered Dissotis, Gutenbergia and Kotschya, mauve Lobelia and yellow Anisopappus and Commelina spp. Looking back, we had a spectacular view over Charleswood Farm to Chimanimani village on the skyline.

As we neared the base of the cliffs the path wound between huge rocks and the undergrowth became thicker and more luxuriant. Tangled masses of creepers, including a species ofHibiscus, the smaller but similar flowered Thunbergia alata ("Black-eyed Susans"), andAnnelina, mingled with Pteridium aquilinum (bracken), while a variety of orchids, ferns and aloes grew on and among the rocks. We found small specimens of Xymalos monospora, a montane tree with characteristic quilted leaves, and tree ferns (Alsophila spp.) Red-leaved Hymenodictyon floribundum grew in crevices in the rocks. While the rest of the party climbed on, the keener botanists fretted over the identity of the Uapaca and Ficus that they encountered. While most of the Uapaca were clearly U. kirkiana, some had smaller, yellow-green leaves and longer petioles. Were they U. sansibarica, which we had identified with some confidence down by the Haroni? Some of the small figs growing on top of the rocks had concave ends to their leaves, while others had square ends. The former had to be Ficus craterostoma; were the others F. natalensis? Unfortunately for the Tree Society, taxonomy is not based on the character of leaves, and variation of leaf form within a species may be greater than variation between species. For practical purposes, one must assume that similar trees growing in a similar habitat with a similar growth form are the same species, and identify the species by the dominant characteristics of the majority.

The dominant trees changed, from Uapaca to Brachystegia microphylla, as we clambered down to meet the river at the base of the gorge that brings it from the mountains. Unfortunately so too did the weather, as the rain set in, and our picnic lunch by the pools and rapids was hurried and uncomfortable. Jill was brave, or mad, enough to swim, and complained of the difficulty of dressing again into already wet clothes. The rest of the party took what shelter from the rain that they could find, swallowed their sandwiches, and beat a disorderly retreat down the mountain, slipping and sliding on the wet path back to the Centre for hot showers, dry clothes and hot tea. The mountaineers did not return until near nightfall, and did not appear to have enjoyed their descent from the top in the rain.

John Lawrence (JAL)

TUESDAY 17

The Tree Soc free reign of Outward Bound was shattered by the arrival of the multitudes for training courses. We were pleased to hear botanical terms used in their early morning briefing. At roll call we distinctly heard: 'John here! Peter here! Philippia!' They were warned: 'Eulophia you get sent packing. Uapaca your bags and go straight home!'

For the Tree Soc the day started on a confusing note when John (of Borrowdale Donkey Stud fame) discovered in van Wyk & van Wyk a most unusual illustration of Ficus craterostoma which we are sure that we had seen the day before. So off we went down the hill and Gill came tumbling after. We sailed past a sign: Strictly No Public Access. Nice to have friends in high places. Traversing an area of Eragrostis acraea - the very coarse grass special to the east, yielded some good views of Eastern Saw-wing Psalidoprocne orientalis, Cape Batis Batis capensis, Augur Buzzard Buteo augur and the Phragmites australis reeds had a few roosting nests of the Thickbilled Weaver Amblyospiza abifrons.

We attempted to sort out the proteas on the hillside. P. petiolaris was distinct enough with the sickle shaped leaves tapering at the base to leave no room for a petiole. But to differentiate between P. caffra, P. angolense and P. gaguedi without flowers presented a problem. We were happy that bushes with multiple dead flower heads were P. welwitschii. The notice board at National Parks put the altitude at 1250 m.a.s.l. and so we saw some familiar friends like Combretum molle, Pterocarpus angolensis, P. rotundifolius and Steganotaenia araliacea.As the going got tough, the tough got going in the opposite direction and we returned through some brilliant Kniphofia sp. and Hypericum sp.

Lunch was a very leisurely affair at Middle Pool - a beautiful spot - again not accessible to the public. There was some energetic swimming by many of the Tree Soc but it was difficult to appreciate fully the delicate mauve Gladiolus overhanging the water whilst in freezing water.

The afternoon walk produced more that we had not seen. Trema orientalis, Ulmaceae, a pioneer species. Vangueria apiculata, Rubiaceae, leaves big,heavy and smooth. Rauvolfia caffra, Apocynaceae, with milky latex. Tabernaemontana ventricosa, smooth fruit. Mark entered a thicket and had his designer label shirt ripped by the spiny Smilax kraussiana, Toddalia asiatica and Dioscorea sp. The latter showed both its methods of reproduction - three winged pods and an 'air potato' - like tuber. A budding collector in seven-year-old Rebecca produced Perotis patens, bottlebrush grass which, apparently, we should know. Derek was off on a mission to collect a wood/charcoal sample of an Ozoroa for microscopic inspection which should clarify if it is the 'wedding vow' species. (Do you take....to be your awful dreaded spouse....insignis and in health).

With boggled minds we retired to the Out of Bounds Bar for some quaffing, yodelling and good company. Many thanks to Pippa and all the group for such a wonderful stay and to Mark for his endless patience with silly questions.

Sue, Dave, Michael and Robbie DuPlessis

WEDNESDAY 18 (Independence Day)

The last day and the day of departure for Harare. However, through Lyn Mullin, we had been invited to Lord and Lady Plunkett's farm, Rathmore Estate, which lies not far off the road back towards the village of Chimanimani.

Here a warm welcome awaited us and we set off on a guided tour of an extensive wild garden. Streams flowed throughout the area, the vegetation was lush and the flora rich in both woody and herbaceous plants. The altitude (approximately 1500m) was much higher than Outward Bound and the trees and plants seen were rather different.

The flora in fact was more like the trees one sees in the higher parts of the Vumba. Here were trees such as Macaranga mellifera (Mountain macaranga), Teclea nobilis (Small-fruited teclea), Myrica pilulifera (Broad-leaved waxberry), Rhamnus prinoides (Shiny leaf) and a species of Heteromorpha. Also very common was Choristylis rhamnoides (False shiny-leaf). Higher up were enormous trees of Albizia gummifera (Smooth-bark flat-crown), with their smooth trunks. Also present were Rauvolfia caffra, Trema orientalis and Solanecio mannii again.

Another typical Vumba plant seen was Xymalos monospora (Lemonwood). Although this is a fairly common eastern districts species, I don't think it is very well known. The leaves are quite large and very variable in leaf lobing and are somewhat quilted with raised areas bounded by the looping veins. Furthermore, the leaves are often a mixture of opposite and alternate. The species belongs to the family Monimiaceae, which is a rather obscure one, at least in the context of Zimbabwe.

From Mabberley (The Plant Book), it appears the Monimiaceae (which has an amazing 440 species in the world) belongs to the order Magnoliales, along with other families such as Annonaceae, Canellaceae, Hernandiaceae and Lauraceae.

Finally, we reached a waterfall, at which spot a Giant lobelia had turned up one year. Was this Lobelia stricklandiae, I wonder? Unfortunately, there was no sign of it this year, although as the area is full of lush vegetation, it could still be around.

Quite apart from the woody flora, there was also an interesting herbaceous component, some of which were new to me and have not, as yet, been named. The morning ended with a very welcome light lunch provided by our hosts.

The return journey for us was uneventful. Although we could probably have made it back, we were very relieved to find diesel, and fill up, at the garage on the Mutare side of Christmas Pass.

---

Special thanks must go to Maureen who put in a lot of effort in organising the trip even though she was not able to go on it herself. We also thank Pippa Browne and Scott for giving us permission to visit Outward Bound and for being so helpful when we were there. Very great thanks also to Robin and Jennifer Plunkett for inviting us to their lovely home, with its interesting flora. A longer visit there would be of great interest in the future.

Mark Hyde