Chairman and members of the Committee wish all members
and their families a very happy Christmas, and
walks in 2005.
Sunday 5th December. The date for our Christmas Social has been brought forward a little.
We are very lucky to have been able to reserve
the educational centre at the Botanic Gardens, Fifth
Street, for the whole day.
All facilities are available so this is an ideal
venue and there will be no charge at the gate. We
would like to thank the Head of the Herbarium and Botanic
Garden Nozipo Nobanda for this generous gesture to the
After tea which will be served at 9.30 am, we will
have a short walk led by Meg Coates Palgrave, the subject
“Christmas Trees in Zimbabwe’ sounds like fun.
After the huge success of last years quiz, Rob and
Adele have compiled another, and this test of GK will
probably be before lunch or after, depending on time.
Please bring some Christmas
fare to share for tea, and bring your own lunch, a wine
glass and a chair. Terry Fallon
has kindly offered to be on guard duty while we are
walking in the garden.
7th December. Botanic Garden Walk.
Meet in the car park at 4.45 for 5 pm. This will be our
opportunity to thank Tom for giving us so much of his
time this year.
1st January 2005. Mark’s first walk of the year will be in the
grounds of the University.
Tuesday 4th January. Botanic Garden Walk.
16th January. Monthly all day outing venue to be decided.
22nd January. Mark’s Walk, venue to be decided.
Please phone J P Felu on Bulawayo 232797 or Jonathan
Timberlake on 286529 for details of the next Matabeleland
LOOMING NAME CHANGES
IN THE GENUS ACACIA:
In an article which appeared
in the October 2004 edition of Tree Life (number 295)
I summarised the very significant
name changes which are about to take place in the genus
Acacia. I am very grateful to Jonathan Timberlake for
sending me a copy of a further paper  by RK Brummitt
of Kew which takes the matter a step further.
Two factors are causing these name changes. The first
is taxonomic research on the genus which implies the
need to split up the genus into various smaller genera.
The consequence of the first factor is that a substantial
chunk of African species would need to be moved from
Acacia into Senegalia, with the residual native species
remaining Acacia. The exotic Australian weeds (wattles)
would become Racosperma.
The second factor is the proposal by two Australian
authors, Orchard and Maslin , to change the type
species of the genus Acacia from what is now called
A. nilotica to an Australian species.
The implication of the second factor would be that
all our native Zimbabwean acacias would move to either
Senegalia or to another genus Vachellia. Only the wattles
would remain Acacia.
This article is concerned only with the second factor.
In order to change the type, the proposal has initially
to go before a committee of botanists who consider the
arguments and vote on the proposal. The paper referred
to above  sets out the result of the vote and the
reasons for their decision.
The vote was in favour of the Australians’ proposal.
The two principal reasons for this were as follows:
vastly greater number of species of Acacia (in the former
sense) to be found in Australia than in the rest of
the world. Acceptance of the proposals minimises name
whatever the decision of the Committee is, there will
still be significant name changes for users outside
Australia, namely, in our case, the transfer to Senegalia.
A number of other arguments
against the proposal were put forward and the paper
explains why they were rejected. As some of these are
quite interesting I am reproducing them below.
was argued that acacias are characteristic of Africa
both in public perception and as an important vegetation
type. However, the Committee felt that they were equally
important in Australia: there they are the largest genus
of flowering plants (more even than Eucalyptus) and
an acacia is the national flower.
acacias are economically more important in Africa. Again,
based on various, mainly Australian, sources, this view
was rejected by the Committee.
widespread use of the name Acacia in floras outside
Australia was referred to; but again this was rejected
on the grounds that many name changes will take place
anyway because of the taxonomic factor.
combinations needed in Racosperma (which would be the
new genus for the Australian acacias if the proposal
were rejected) have already been made (December 2003).
However, despite their availability, the Committee felt
that this should not be a factor in itself.
of the proposal will set a precedent and lead to many
similar applications in future; this was felt to be
unlikely by the Committee, which has never had to consider
a proposal to stabilise over a 1000 names before.
Reference was also made to
the changes to the genus Cassia, which led, in our case,
to most species being transferred to Senna or Chamaecrista,
leaving only two species in Cassia. There, the Committee
points out, there appears to have been wide acceptance
of the changes and no proposal to conserve Cassia was
Where does all this leave the
Tree Society and the ordinary man in the street in Zimbabwe.
There is no doubt in my mind that changes of name to
such an important genus will cause a
lot of unhappiness amongst
members. I don’t think it will particularly matter whether
those changes result from taxonomic opinion or international
The case of Cassia is of some
relevance. Many older members still use Cassia, but
as the names (e.g. of Senna singueana) have been adopted
in popular floras, so they have gradually become more
accepted. However, Cassia is nothing like as important
a genus as Acacia; it is neither so instantly recognisable
nor as widespread nor as common nor so commonly encountered
in our day to day lives.
Faidherbia is another example of a well-known species
with a major name change. Again, this does seem to have
been generally accepted, even if with a lot of muttering.
I would welcome any views on this subject. If members
could email them or write to me, we can either publish
them directly or I could summarise the opinions I receive
in a future Tree Life. Should any further updates be
necessary I will arrange for them to be published here
Report of the Committee for Spermatophyta 55: Proposal
1584 on Acacia. RK Brummitt in Taxon 53(3): August
Orchard and Maslin in Taxon 52: 362-363, 2003.
BOTANIC GARDEN WALK:
5 OCTOBER 2004
The first walk at the summer time of Tuesday evening
and we welcomed Tom back from his holiday in Europe
to lead us again.
There was no pre-set subject; Tom just discussed whatever
came up that was of interest.
The first species seen was Cordyla africana (the Wild
Mango), a lowveld, riverine species. It has 1-pinnate
leaves (with glandular dots and streaks) and fleshy
fruits which somewhat resemble a mango. In the Gardens
it was flowering and bearing its orange flowers and
it looked very lovely indeed. Tom referred to very large
trees indeed which occur along the lower Save River,
for example at Chipinda Pools.
A small, flowering Acacia nigrescens (the
Knob thorn) showed the features of this tree species
very clearly. The trunk was densely covered in the ferociously
armed knobs; the flowers which were white were basically
just finishing. The relatively large leaflets which
are few in number were also seen. The flowers were in
spikes and the thorns are curved prickles - should we
call this Vachellia
(See my article on the name changes in Acacia).
Ficus verruculosa is a locally common species of fig, occurring and riverine
and wet situations. It is unusual in that it is quite
small, usually up to about half a metre in Zimbabwe.
Tom remarked that the figs made quite nice eating. A
discussion took place about the strange nature of the
"fig" and the relationship of the species
with the fig wasps.
Newtonia buchananii (the Forest newtonia) occurs in forests in the E districts
at medium and low altitudes. Tom reckoned that the upper
limit for it is 1300m. Like the Acacia nigrescens, the
flowers are tiny and are arranged in spikes. As with
most Mimosoideae, the leaves are 2-pinnate. Tom mentioned
that this specimen in the wild would have a trunk 30
m high with a crown above that; however, here, in the
open, the trunk was short and the crown effectively
on the ground. The seeds of this species are winged
- an unusual, possibly unique, feature within our Mimosoideae.
Hurrying past a specimen of the Bindura bamboo, Oxytenanthera abyssinica, which was in flower, we came to a colony of wild gardenias
in flower; these were Gardenia
volkensii. Tom mentioned that this a 1-day wonder
with white flowers turning through various shades to
yellowish-brown. It has a distribution which is difficult
to understand, ranging from the edges of pans in the
lowveld to sandy well-drained woodland.
A smallish Brachystegia
was in flower just above head height. It is not often
that I've looked at the flowers of brachystegias, other
than the msasa. This is obviously rather later-flowering
than the latter species.
Parinari curatellifolia (the Mobola plum) is very well known to us all, but
as Tom remarked, you don't often notice the flowers,
which are tiny and a very pale pinkish-lilac in colour.
The tree often smells very badly and it doesn't seem
to be clear which part of the tree is responsible for
this. Tom mentioned that it is extremely fire resistant
with its thick bark,
Finally, near the Herbarium, we came across the national
flower of Jamaica, Guaiacum
Like Balanites, this has compound leaves with just two
leaflets; the family is Zygophyllaceae (into which Balanitaceae
is sometimes placed). The trees are a source of lignum-vitae
and are some of the hardest commercial timbers.
NATURE RESERVE, MTOROSHANGA:
17 OCTOBER 2004
In the hot and
usually dry month of October, it is sometimes a bit
difficult to find places where the trees actually have
leaves and there is anything much to see. Our outing on this warm and moist summer's
day was once again to Maringambizi Nature Reserve, where
we were the guests of Barbara Scheidler.
Our drive there took us along the road which runs northward
on the western side of the Great Dyke. At some point,
we turned at right angles away from the mountains into
a fairly flat area broken by occasional scattered kopjes.
After assembling, we set off in our vehicles to a nearby
area where camping is permitted (sadly quiet at the
moment) and there are some nice rocky and woodland habitats.
This was the same place we visited 2 years ago. To some
extent our fears were realised as many of the trees
were leafless with that peculiar combination of a wintry
vegetation and high temperatures.
As some background, the altitude of the place was 1270
m, a bit lower than Harare, and certainly low enough
for the trees to be different. One of the first trees
we came across was difficult to name and caused a certain
amount of debate and indecision. Our first attempt at
the name was Euclea
natalensis but eventually we decided its leaves were not dirty enough
and we moved towards Diospyros
later we considered D. mespiliformis, which was our eventual
In the woodland was Vernonia colorata. This
is one of the relatively few species in the Asteraceae
which has a tree habit. It is also interesting in being
winter-flowering. It is very close to Vernonia amygdalina but can fairly easily be separated by looking at the seeds
(achenes); these have papillae only (minute nipple-like
protuberances) in V.
colorata but have hairs as well in V.
amygdalina. The exact distinction in habitat between
these two is not clear to me, but V. amygdalina
seems to prefer higher-rainfall areas whereas.
V. colorata often favours drier stonier
Diplorhynchus condylocarpon (the Rubber tree) was present and was in flower. It
has tiny white flowers with 5 lobes. Also seen was Afzelia quanzensis (Pod
mahogany) together with some old pods to confirm the
identification. The distinctive green peeling bark of
made identification of that species easy even without
In the woodland was Uapaca nitida (Narrow-leaved
mahobohobo), the smaller-leaved cousin of the more common
Uapaca kirkiana (the mahobohobo). We do occasionally see this species, usually
to the north of Harare, but it is rather local. In this
case, the trees bore fruit, which were smaller than
those of the mahobohobo itself.
After a while we headed down towards the dam. Dark
clouds were massing and there were distant rumbles of
thunder. Here was a burnt area, on which the typical
spring flora of pyrophytes, which we often see around
Harare, was present.
Particularly attractive were the red flowers and fruits
platypetalum and also a very pretty orange-flowered
herb, called Nesaea
heptamera. The specific name means "with
parts in 6s".
Despite the thundery noises, we went on to visit the
dam edge, and afterwards walked back to the cars, passing
through some rocky hills. Here were the striking pale,
peeling trunks of Albizia tanganyicensis
and some fine specimens of Kirkia
acuminata. In the end the storms moved
away and we had a very pleasant lunch sitting outside
the cottages on the lawn.
It is of course unusual these days for us to go so
far out of town for the day and perhaps because of this,
or perhaps the cost of petrol, our numbers were well
down and we just struggled into double figures. This
is a pity as the Reserve is well worth visiting and
we have plans to return there at a wetter time of the
year when we hope that there will be more to see.
Our great thanks go to Barbara for hosting and guiding
us throughout the day.
This file, labelled Tree History – Follow-up Papers,
also contained what appeared to be the rough draft of
an address to an unspecified group.
The undated draft was entirely handwritten, and
there was no evidence that it had ever got to the stage
of being typed. Clues
to a date for the draft were (1) an indication that
was then becoming accepted as the correct name for Acacia albida, (2) a reference to a contribution
by the author to the 1978 edition of the Gardening & Floral Diary, and (3) the use of the name Zimbabwe.
We can probably take it that the material in
this file was put together in the mid 1980s.
Trees and Wildlife
The leaves and shoots of a very wide range of trees
are browsed by wild animals—and often, for that matter,
by domestic stock. Fallen leaves are also frequently taken, particularly
when grazing has become poor.
The pods of numerous trees supply nourishment to game,
and a favourite sight amongst Zimbabweans who visit
Mana is that of elephant gorging themselves on the apple-ring
pods of Faidherbia albida.
Mopane trees are highly prized for browse. Elephants love them, and the dry leaves, which
are rich in phosphorus, are picked up by buffalo and
(shepherds tree, or white-stemmed boscia) has particularly
valuable foliage—described in one book as “as good a
feed as lucerne”. The browse line makes the tree look as if a
meticulous gardener has expertly trimmed it.
The same sort of browse line is often a feature
of trees at Mana Pools on the Zambezi, where Trichilia
emetica (Natal mahogany) is so favoured by animals—even
grazing animals like impala when the grass runs out.
There seem to be mighty few trees that are not utilized
in one way or another by wild life, although some with
particularly nourishing properties naturally suffer
more predation than others do. Even Spirostachys
africana (tambuti), which has toxic properties as
far as humans are concerned, are browsed on occasion
by animals, mainly, perhaps, when the leaves are dry—but
not necessarily so, because porcupines gnaw the bark
seemingly at any time.
Some additional trees, beloved of animals as dietary
delicacies, are similarly distasteful to humans. Giraffe find our thorny acacias irresistible—leaflets, thorns, and
all. Only the
sword swallowers amongst us would be likely to share
this animal’s tastes!
The fruit of Pseudolachnostylis
maprouneifolia (duikerberry) is a great favourite
of the various antelope—but it tastes ghastly!
Xanthocercis zambesiaca (nyalaberry)—that
magnificent species, which grows particularly well in
the Save-Limpopo Valley, and may be known to those who
have visited the Rupisi hot springs—has a fruit that
is similarly popular with game animals, but is not a
Black rhino have been known to munch, pensively, on
the leaves of Obetia
tenax (tree nettle)—a tree that has the endearing
quality of raising blisters on any human hand that happens
to brush against its stinging hairs. The thorns of Gymnosporia buxifolia (spikethorn) do not seem to bother browsing
impala, nyala, kudu, giraffe, or anything else.
At Mana Pools we have watched baboons enjoying the
flowers of Kigelia
africana (sausage tree), presumably for the nectar.
The only animal I know that seems to eat the
fruit is the rhino.
[Comment 2002: According
to Malcolm Funston (1993), Bushveld
fruits of Kigelia africana are occasionally eaten
by bushpig, and even more occasionally by baboons. AA Pardy (1953) Notes on Indigenous
Trees and Shrubs of Southern Rhodesia, reported
that unripe fruits are very poisonous, and ripe fruits
birrea) fruits are relished by game and by humans,
although some may find them a bit tart.
Other wild fruits that are sought after by animals
and humans are Berchemia
discolor (bird plum, or brown ivory), Hexalobus
monopetalus (shakama plum), Friesodielsia
obovata (northern dwababerry), Parinari
curatellifolia (muchakata, or muhacha), Uapaca kirkiana (mahobohobo), Tamarindus
indica (tamarind), Cordyla
africana (wild mango), Dovyalis
caffra and D. zeyheri (kei-apples), Syzygium spp (waterberries), Englerophytum magalismontanum (stemfruit),
species (sometimes called jackalberries or star-apples),
Strychnos species (monkey oranges), Carissa species (num-nums), Vangueria
species (the so-called “wild medlars”), Artabotrys
species (hookberries), Flacourtia
indica (governor’s plum), Annona
species (wild custard apples), and Garcinia
There are also, of course, the many wild figs—all edible,
but not all of them very palatable.
Nonetheless, they are among the edible resources
we share with our wild animals and birds.
Among the birds, every one of these wild fruits figures
on the menu. Not
all birds are predominantly fruit eaters, but those
that are not are only too pleased to sip at the nectar-rich
flowers of some of the fruit trees, or to take their
choice of the insects and caterpillars, grubs and rodents
that visit the flowers or fruits.
This is why it is so vitally important to leave
old and rotting (or composting) vegetation where it
is, and not automatically to regard a leafless or broken
branch as firewood. It is from old wood, the mosses, the fungi,
and ant-ridden remnants of fallen bark and branches
and seed pods that beetles and many other creatures
emerge to help in the food chain of wild life, from
the minutest of grubs to the most majestic of birds
and animals. It is in the cracks and hollows of living trees
and bushes that many of them nest and find shelter.
To be continued.