Expedition no. 16: Tree Society visit to the Vumba: 8 Aug 1997-11 Aug 1997

A visit by the Tree Society, during which they stayed at Seldomseen and visited the Bunga Forest and the Burma Valley


Generate a list of species for Expedition no. 16

Description

Seldomseen: 8 August 1997

A contingent of Harare members spent the Heroes Weekend this year at Vumba, residing at Seldomseen cottages off the Nyamheni road not far from Bunga forest. On Saturday 8th August we spent the day looking around the offerings of the forest which flanks both sides of the Seldomseen property, and also looking at a few of the exotic plantings.

We were happy to be joined by Celia Manson, the previous owner who, along with her late husband Alex, can proudly take credit for much of the development of the property. We were also pleased to be joined later by Tackie Bannerman whose knowledge of local plants is something of a legend and proved very useful.

We foregathered on Celia's lawn and were introduced to Smilax anceps, a creeper with medium-sized simple leaves growing here in ordinary garden shrubbery, but more commonly known from forest edges and nearby grassland where the vicious hook thorns catch arms and ankles of the unwary. Polygala virgata, Erythrina lysistemon, although locally common indigenous shrub and tree respectively, had been planted on the garden fringes.

At the garden forest interface we were soon acquainted with three of the local forest standards - Macaranga mellifera with the large, simple, almost peltate leaf, Aphloia theiformis, with small serrated simple leaves arranged in alternate rows on opposite sides of the branchlet, and Schefflera umbellifera, characterised by palmately compound leaves, the upward pointing leaflets of which more often than not are limited to three giving one the impression that it is a trifoliate. It also almost invariably has buds, flowers or fruit in various stages of development.

Gouania longispicata, was a climber festooned over some of the trees visible from the back garden. lt is aptly named, for it was covered in a profusion of long, creamy yellow flower spikes. On the forest edge was a straggling specimen of Prunus africana, with pink-petioled slmple leaves not unlike those of apples. When crushed, the leaves gave off a very noticeable smell of cyanide/almonds, which is consistent with the fact that Prunus is in the same family with apples and almonds - the ROSACEAE.

On the forest floor here, and ubiquitously elsewhere, was a straggling shrub Mimulopsis solmsii (ACANTHACEAE). This has an untidy appearance, having been well chewed by insect browsers, so it does not look like much to write home about. However, apparently every few years (not annually) it erupts in an orgy of blue flowers "gregariously'', i.e. all plants synchronising their flowering precisely rather like some bamboo species do.

A pink-flowering Dombeya burgessiae was also in the back garden along with Cussonia spicata, and a small Albizia schimperiana. (We saw some much bigger specimens later on our trip).

On the driveway Keetia gueinzii, a woody climber, was clambering in the shrubbery. A tree along this part of the driveway not previously seen was Sapium ellipticum (EUPHORBIACEAE), which has dark green elliptical leaves with a tapering apex arranged altemately along the branch. It has the English common name of the "jumping seed tree" because insect larvae infest the seeds and their sudden movements inside can cause the seeds to jump into the air. We did not see any seeds. Heteromorpha arborescens (a.k.a. H. trifoliata, of the carrot family UMBELLIFERAE also appeared along this driveway.

Setting off down the path looping around to the west of the driveway, one enters forest dominated by some very large Syzygium guineense subsp. afromontanum trees, together with what we assumed was Albizia gummifera, the forest pioneer Polyscias fulva, along with the Macaranga mellifera and Schefflera umbellifera mentioned previously. Rawsonia lucida was also noted although not as large and frequent as seen in the Bunga forest the following day. We did however note its ‘labels’, i.e. flaking bark revealing patches of orange underbark, confirmed by the dark green glossy leaves with a very sharply serrated margin, almost holly-like, arranged strictly alternately along the branchlets. Amongst the taller trees was also a lone Ficus sur reaching up from ground level to the canopy.

The understorey contains a plethora of interesting smaller trees and shrubs including perhaps the commonest, Psychotria zombamontana, the 'other' member of RUBIACEAE family aside from Pavetta with bacterial nodules dotting the leaves. We commonly encountered Piper capense the wild pepper, always conspicuous because of its swollen nodes where the petioles of the leaves join the stem. Coates-Palgrave notes that pepper can be obtained from this species. We saw another member of this family in the shape of the indigenous Peperomia tetraphylla, growing delicately as an epiphyte on the bark and in forks of the big trees. Another common understorey constituent is Erythroxy!um emarginatum, which we from Bambazonke know more as a member of the granite koppie communities. This is also true of Diospyros whyteana, which we see from time to time in the koppies (Marondera springs to mind), and which is so distinctive with its glossy leaves and hair fringed margins.

We got to know Ochna holstii a small, delicate cousin of the Ochnas we know so well from the highveld. It tends to have slender horizontally held branches with rather narrow lanceolate leaves. The midrib is prominent on both surfaces of the leaf as with the other Ochnas.

The list goes on – Dracaena fragrans, the smaller of our 'dragon trees', an epiphytic orchid Polystachya cultriformis, Myrica pilulifera, which we saw near the Pungwe last year, Xymalos monospora, lemonwood, with its distinctive 'quilted' dark green serrated leaf, Cassipourea malosana, a small tree of the mangrove family RHIZOPHORACEAE, with dark green serrated opposite leaves known as the 'Lesser onionwood', Peddiea africana the small shrub of the THYMELAEACEAE family producing small bunches of green trumpet flowers. Mark demonstrated the family characteristic of leaves/twigs stripping fibres of the stem when pulled off.

The lemon family, RUTACEAE, was represented by Toddalia asiatica, a very prickly climber, Teclea nobilis, a trifoliate evergreen shrub, and Clausena anisata, a rather small slender tree, the leaves of which give off that unique lemonish smell that gives rise to the fascinating Afrikaans name perdepis, i.e. horse-? - you guessed it! Of the climbers, Rhoicissus tomentosa is very noticeable with its broad almost round leaves and liana trunks, some as thick as your thigh, climbing high into the canopy. This is the climber which apparently reminds Thom Muller of his misspent youth in the cafes of Switzerland where this species was often used as an indoor plant.

In the afternoon we revisited forest to the north of the forest and the forest edge/grassland beyond. Here we saw a number of trees/shrubs familiar to us on the highveld such as Dodonaea viscosa the sand-olive, Aeschynomene nodulosa, the' small-leaved false-teeth tree' so called because of its pod resembling a row of teeth, Psorospermum febrifugum, the Christmas berry, and Catha edulis, bushman's tea - the infamous 'qat’ drug of Somalia, Yemen etc., which does not seem to be used as a drug in this part of Africa. Rhus chirindensis is the common Eastern Highlands Rhus familiar to those who frequent Nyanga area, we saw this on the forest edges. It often has a reddish appearance with red in the midrib, veins or petiole. Also familiar to Nyanga visitors would be the yellow flowering Hypericum roeperianum, the large-leaved St John's wort. Yet another Nyanga resident seen here and also common in the Cape was Kiggelaria africana. One familiar tree in this area was an alien escapee, Homalanthus populifolius, Queensland poplar or umbrella tree, often seen with a few red heart shaped leaves amongst the green foliage in city gardens.

A common understorey creeper was Behnia reticulata. At first sight this looks like a broad-leaved creeper, but a closer examination reveals parallel veins typical of the monocotyledons. This particular plant is a member of the PHILESIACEAE, a family closely related to the ASPARAGUS family, Indeed, this species really looks like a broad leaved asparagus.

Another climber which I was particularly pleased to find was Strychnos lucens. Most members know Strychnos as the range of small woodland trees known alternatively as bush oranges or monkey oranges. However this species is a forest climber, considered rather rare. The usual Strychnos clue was present, that is, the three prominent veins coming from the base of the leaf. It had some unripe spherical fruit on it, a little smaller than a ping-pong ball. One distinctive feature which we were delighted to note was the occasional appearance of paired woody tendrils, designed to facilitate climbing. These look a little like the astrological depictions of Aries' horns.

I have to express my indebtedness to Mark Hyde who led us around and unveiled to us many a plant that would otherwise have remained nameless.

Philip Haxen

Bunga Forest: Saturday 9 August 1997

The Bunga forest is only about 2km beyond the tum off to Seldomseen, and we began our walk from the car park on the left at the entrance to the forest. Although the forest at Seldomseen was visible from the car-park, the species distribution here was markedly different.

We soon found (and Mark identified) Mostuea brunonis, 'heart fruit’, which belongs to the family LOGANIACEAE along with Strychnos and Anthocleista. The common name also refers to a species of Hymenocardia. A few small fruit were collected, although most plants had shed all their fruit.

As usual we needed to attempt identification of trees by trunk and bark features followed up by use of binoculars. Having settled on the orange bark to identify Rawsonia lucida the day before, we almost misidentified Syzygium guineense ssp. afromontanum, whose bark was similar. However, the larger Rawsonias lacked the marked buttressing which characterised the Syzygium.

A number of small yellow-woods, Podocarpus latifolius were seen here, and on the other side of the road, but no large specimens could be found. Perhaps these were selectively harvested for their valuable timber sometime in the past. The liana Schefflera goetzenii grew thickly in the trees especially those close to the road.

Having crossed the road, we skirted the forest and at last found Croton sylvaticus in leaf which could be compared with Macaranga. The pair of small glands on the top of the leaf were clearly visible on the Croton leaf but not on that of Macaranga. Several large rough-barked trees were identified as Faurea forficuliflora ('Manica beechwood'), and the few remaining crimson flowers were visible to confirm this.

Turning into the forest after a brief encounter with angry bees, we made our way onto the path leading to the grove of tree ferns. Along the way we found Cassipourea malosana ('Lesser onionwood') seen previously on the day before at 'Seldomseen'. Some time ago this tree aroused interest when it was implicated in the seeming sex change of chickens on a farm in Mocambique. Although it was thought that a chemical in the bark was responsible for masculinisation of hens which were run on the sawdust, it was finally shown that the chemical came from a fungus growing on the sawdust.

Cola greenwayi was an interesting find. Like many other species here it has a limited distribution.

The final destination proved to be as worthwhile as in the past. The spiny tree ferns, Cyathea manniana were numerous and healthy, and Kim would have been pleased with the stem protruberances, some of which entered the soil and could be followed to a new plant, showing clearly that vegetative reproduction occurs from these elongated structures. No mention of these can be found in the fern and tree books referred to. Most of the tree ferns bore a cover of Asplenium hypomelas, a fern which very often grows as an epiphyte on this particular tree fern. Many of the ferns were estimated to be 5 metres in height.

Nearby, the large leaves of Neoboutonia macrocalyx (EUPHORBIACEAE) were seen. Those of us who made the trip before associated this unusual tree with the spiny tree ferns, and it was heartening to see that things were still the same.

Cheryl Haxen

Monday 11 August: Along Essex Road in the Vumba

Amazingly the convoy of cars left Seldomseen at the pre-determined time heading for 'THE' lay-by to meet Tackie. Here a small stream disappears under the road before tumbling steeply down the gwasha. On previous Vumba trips many happy hours have been spent botanizing at this site. Today, however, the ground was rather sodden and squelchy so, after admiring the ground cover of busy lizzies (Impatiens ceciliae) and buttercups (Ranunculus multifidus), we set off down the Essex road to the Boswell-Browns, 20 kms and four hours away. Tackie had a mental list of 'Eastern District Delights' to show us which entailed frequent and enchanting stops.

Macaranga mellifera seemed to be the main species along the road, and Myrianthus holstii was unmistakable, - tall wide trees with enormous digitate leaves which C.P declares ‘land on the forest floor with an audible 'plop'. The bonus was seeing the hand grenade-shaped fruit. Common too along this stretch of road was another member of the family MORACEAE - Trilepisium madagascariense, (the False fig) easily recognized by its drooping branches and very shiny dark green leaves with conspicuous drip tips. A common creeper with golf ball sized speckled fruit was Landolphia sp., perhaps kirkii, a plant with copious milky sap in the family APOCYNACEAE. It is reputed to be edible. Would I try it? Perhaps not.

At the next stop, a very tall, big leafed fig defied immediate identification. After much debate, speculation and in the evening reference to the books, we agreed on Ficus scasseIatii. One of the common constituents of the forest understorey here was a species of commercially grown coffee, perhaps spread by birds. We wondered if it could become a problem in time, but in our rather short visit we did not notice another population. Tackie?

Time was racing along and we got just a glimpse of Tackie's ‘Duzi Duzi' tree fern nursery and adjacent forest. Must go back there one day.

Hugh and Tuffy Boswell-Brown gave us a great welcome to their Crake Valley Farm, and we were invited to have our lunch on the verandah and lawn before our walk. The vegetation on the farm was different to that seen earlier. Several exotics have escaped, notably ginger lilies (Hedychium sp.) and something akin to Syzygium jambos the Rose Apple.

It was interesting to hear from Hugh that in this area the plant with bright orange sap in the family GUTTIFERAE, Harungana madagascariensis is troublesome and can be invasive. Climbing to the tops of the trees in the forest was the fern Lygodium kerstenii, known locally as the paraffin creeper as it is very volatile and flares rapidly when set alight. Kim once told us that this fern has the longest leaf in the fern world.

Jessica's pure flute notes drifted across the meadow, providing a delightful ethereal atmosphere while we walked along the forest edges becoming re-acquainted with Markhamia obtusifolia and M. zanzibarica, Antidesma venosum, Albizia adianthifolia (crocodile bark) Albizia gummifera (smooth bark) and Albizia schimperiana (smaller leaflets). After battling to separate the Albizia species it was somewhat disconcerting to hear ' that hybrids are not uncommon’, ....... groan.

Bersama abyssinica showed its wonderfully winged rhachis and attractive fruit, some of which was collected by Mike and Robby du Plessis. The red seeds with yellow arils are released when the round woody fruit splits and opens like a water lily. Clerodendrum swynnertonii, laden with shiny black fruit and whose leaves did not smell unpleasant when crushed, was new to most of us ; Clausena anisata lived up to its Afrikaans name of Perdepis: and the Schrebera alata whlch we saw was a little different - with 3 pairs and a terminal leaflet. It was interesting to see the two species of Macaranga almost side by side M. capensis and M. mellifera and, common on this farm but seldom seen by the Harare members, Sapium ellipticum with copious milky sap and serrated leaf margins.

Tackie and Hugh, eager to share further delights, were waiting restlessly for the tail-enders, and after stocking up with Vumba Cheese at the cheese store the curious set off in vehicles once again. This time to another vegetation type just 5 km along the road. One of the surprises was Brachystegia utilis, to my eye rather like Brachystegia glaucescens but with a very rough bark; - and another was to find Coddia rudis last seen on Nyoni Hills. We stopped to gather seeds from a laden Entada abyssinica. The paper thin pods which are about 20 cm long split into horizontal pieces each bearing a single bean. Here Bindura bamboo - Oxytenanthara abyssinica grows tall and in dense colonies.

Kealagh always saves the 'best for last' and so it was this week-end too. In the rapidly fading Iight near the bridge which crosses the Zonwe River we came across a 'mystree'. The bipinnate leaves were enormous, my specimen was 72 cm (larger than the whole sheet from Fingaz used for pressing). The asymmetric leaflets were alternately arranged - a feature which Phil reminded us occurs only with Burkea (which it most certainly was not) and Erythrophleum - so what we had was Erythrophleum suaveolens, the forest ordeal tree. A really exciting ‘first’ for most of us in the group. It was now dark and we just had to go home.

Our thanks to Hugh and Tuffy Boswell-Brown for their warm hospitality and to Tackie for giving up his weekend to show us so many wonderful plants and places.

One of the challenges this weekend was to find a reliable and easy way of separating the look-a-likes - Croton sylvaticus and Macaranga mellifera when only leaves are available,

We came up with:

Macaranga

(a) 2 flat plate-like glands at the base of the leaf;

(b) The undersurface of the leaf is densely gland dotted

Croton

(a) 2 stalked or stipitate glands where the leaf stalk meets the leaf blade

(b) The undersurface of the leaf is covered with stellate hairs.

Maureen Silva-Jones


Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2002-17

Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M. (2017). Flora of Zimbabwe: Expedition no. 16: Tree Society visit to the Vumba.
http://www.zimbabweflora.co.zw/speciesdata/outing-display.php?outing_id=16, retrieved 21 October 2017

Site software last modified: 26 December 2016 8:34pm (GMT +2)
Terms of use