[Illustration: THE KUKA OR BAOBAB TREE
Adansonia digitata Linn.]
THE USEFUL TREES
OF
NORTHERN NIGERIA
BY
H. V. LELY
_Assistant Conservator of Forests_
NIGERIA.
Price 10/-
Published by the Crown Agents for the Colonies,
4, Millbank, London, S.W. 1.
1925.
[Decoration]
CONTENTS.
* * * * *
PREFACE vii
DESCRIPTIONS OF SPECIES IN ALPHABETICAL ORDER 1
APPENDIX I.—TABLE OF FLOWERING SEASONS 121
APPENDIX II.—LIST OF SPECIES ARRANGED IN FAMILIES 126
INDEX OF NATIVE NAMES 127
PREFACE.
* * * * *
The text and plates of this volume have been prepared with the primary
object of identification of the trees of the savannah forests of
Northern Nigeria. The volume is, in no sense, a Flora, and no attempt
has been made to include all the species found in the region under
survey. Trees, being distributed over a large number of Families of the
plant kingdom, are a small proportion of the total number of flowering
plants, and their systematic arrangement would not, except in a few
cases, be an aid to identification. Some 30 Families are represented
by the 120 species included, in one of which there are as many as
36 species. The botanical names are arranged, therefore, in their
alphabetical order so as to group certain genera and species whose
similarity aids identification and to make the volume, in its index
form, handier for reference.
The text is arranged in paragraphs, the first giving a general
description of the form, height, girth, habitat, locality, &c.,
successive paragraphs describing in detail the bark and slash, thorns,
wood, leaves, flowers, fruits and seeds, with a few notes on uses
where these are known. These paragraphs are in uniform order for rapid
reference.
The text is supplemented by drawings of the flower, leaf, thorn, fruit
and seed, sketched from the living specimens. Wherever possible the
drawings are actual size to avoid calculations from enlarged or reduced
figures, but a number have been enlarged to show structures, or reduced
owing to their actual size. In several cases sections of various parts
have been made to illustrate peculiarities of structure, a pocket lens
being used for this purpose, though practically all the parts drawn are
visible to the unaided eye.
The majority of the botanical names have been verified through the
Herbarium of the Royal Botanic Gardens at Kew.
In describing the woods, few of which are in use and many of which
are little likely to be of use, an attempt has been made to strike a
path midway between the complete technical and botanical description
employed with regard to timbers and a vague statement as to colour,
quality, hardness and grain which helps little to distinguish the
individual from others like it. Most of the woods are described from
samples collected by the author and shaped by the Sokoto Arts and
Crafts School. I am indebted for these, and for the facilities offered
for observing their behaviour under tools, to Mr. W.E. Nicholson.
The dry weight of seasoned wood is given in all cases and in this
connection it may be noted that a number of species produce heavier
wood in the north than they do in the south.
A table of flowering seasons has been appended, with a few notes on its
significance.
A second appendix arranges the 120 species under their Families. The
_Genera Plantarum_ of Bentham and Hooker has been followed.
Finally, there is an index of _Hausa_ names for reference to the plates
and text, whose numbers are given in the index. A blank column has been
left in the index for the benefit of those who may desire to collect
either additional _Hausa_ names or the nomenclature of other tribes. It
is hoped that the scope of the volume will be enlarged thereby, so as
to cover other parts of Nigeria where the trees are the same but the
language different.
The botanical name, being universal, is always given preference. The
native names, variable and unreliable as they often are, should be a
secondary consideration, their importance resting in their being a
means of communication with the native rather than a short cut to the
botanical names. In a country where there are several native names for
one tree or one native name for several distinct species, the knowledge
gained is either limited to a small number of trees or applicable to a
small area of country. But once examined and properly identified, no
number of native names need confuse the real identity. In collecting
native names a warning should be given against the ignorant or
ready-to-please native, and independent corroboration is advisable
before accepting a name as worth recording. At the same time it is a
fact that names genuinely differ in quite small areas of country where
the same language is spoken, and a knowledge of the botanical names or
real familiarity with the tree species is essential to reliable work.
The identification of 120 species, though seemingly not a large
number, is sufficient to afford a thorough familiarity with most of
the savannah forests and makes further species, not included here,
stand out all the more clearly from their no longer similar companions.
Numbers or economic values of further species are sufficient
justification for forwarding these for identification to Kew, if they
cannot be named from their resemblance to known species or by means of
a Flora.
In selecting the 120 species to be included in this volume, the author
has had to exercise his own discretion. The collection has been made
between 9° and 14° N., and those who know this area will find a great
deal they require, while some, in the more northerly latitudes, will
find little of importance that is not included. Others, however, will
meet with unfortunate omissions, for the following reason: South of
11° N. certain species which more truly belong to the evergreen and
intermediate forest zones have established themselves in considerable
numbers by streams, in valleys and in pockets of rich soil with
surroundings suited to their propagation. Either all or none must be
included if this volume is to be representative of such regions, but
since they are not truly savannah species their inclusion here is
beyond the scope of this volume, which would have to be enlarged very
considerably to cover even the forests in the Benue region and south of
the Niger, where savannah abounds. All the species included here occur
up to 11° N., and with five exceptions up to 12° N., while nearly all
occur below 10° N. and many much further south.
A selection has been made in the case of some genera, _e.g._, _Ficus_,
and _Combretum_, to familiarise the characters of trees which occur in
large numbers and are typical of savannah forest. Some of these are
of little importance beyond their occurrence in numbers over large
stretches of country. The value of trees varies largely according
to locality. Timber value is of little account in regions where it
is inaccessible and unexploitable. Food, medicinal and other values
take precedence where there is a large population demanding economic
produce, and many species must be accounted valuable merely as a
soil covering for the prevention of denudation, fixation of shifting
surfaces, protection of new growth, grazing areas, precipitation of
moisture, retention of conditions advantageous to agriculture or as a
basis for the introduction of new, or the encouragement of existing
valuable trees from the forestry standpoint. The advance of agriculture
or the condensing of population intensifies these values by the
destruction of the better types in favour of the poorer, and by the
increased demand for the products of the better types. There are many
instances of valuable products being obtained from forests which are
not only some distance from habitations but whose soil is of a nature
that precludes any possibility of supporting a population, since it
will not produce crops. For example, _Sclerocarya birrea_ (Danya) grows
to large sizes in some parts of Sokoto Province where the soil is of an
unworkable kind and where, over wide areas, there are no people. Yet
this area is visited from all over the country and hundreds of trees
are felled for the manufacture of mortars, trees in many cases suitable
for two or three mortars being exploited for one only.
Though much has been written about the various types of savannah
forests, a short account of them will not be superfluous here. First
it may be pointed out that savannah forests vary so much in their
composition and distribution that a survey is practically impossible,
and if made, would have to be revised annually. Savannah is a
particularly aggressive form of forest growth. Given the opportunity,
it at once occupies more land and on its own ground the inferior
types oust the superior wherever there is an opening. Any extensive
area of cultivation, if abandoned and allowed to regenerate its tree
growth, lets in secondary forests containing species which are less
exacting as to soil and moisture conditions, and the depreciation of
these conditions to the farming methods stops the competitive growth
of the trees which formerly occupied the area. Where the area cleared
is sufficiently small and the period short enough, the conditions are
retained, and are able to close up the clearing with little loss by
degeneration.
The fringing forests, belts of evergreen and deciduous trees on the
banks of streams, are continually hard pressed by the broad wedges
of open savannah between them. Fires take toll of them every year
and cultivation not only pushes them down stream from the source
but interrupts and cuts them up into islands exposed to threats of
extinction.
Savannah is very topographical, and though, within broad limits, it can
be divided into two main types, Tree and Bush savannah, the two are so
distributed or blended that the differences are often unrecognisable
and not able to be recorded in a survey.
Tree savannah is recognised as a tall type having a light, closed
canopy, with a sprinkling of under-shrubs and a sparse growth of grass.
Bush savannah is a more open growth of less height, more spreading and
lower branched form, with no canopy, and many stunted shrubs and a
dense growth of grasses which are normally burnt out each year. There
is every variation of this latter type from _Combretum_ and _Guiera_
scrub of barren soils or stony plateaux to the type which closely
approaches that of Tree savannah.
The following are some of the recognised sub-types:—
PARK SAVANNAH.—This is a natural or artificial formation, the latter a
product of agriculture, and is a two-storeyed growth composed of large
type trees scattered about and dominating an undergrowth of smaller
trees. Type species are _Parkia filicoidea_, _Butyrospermum Parkii_,
_Afzelia africana_, _Tamarindus indica_, _Acacia albida_, etc. In
the artificial product the large trees often owe their presence to
their value, having been allowed to stand when the land was cleared
for farms, the lower storey being a subsequent growth whose height
depends on the period that has elapsed since the farms were abandoned.
Natural Park Savannah is well represented by the superior size of
_Afzelia africana_ or _Paradaniellia Oliveri_ over the lower storey
of _Terminalia_ and other species which cannot attain the height or
proportions of these large trees.
FRINGING FORESTS.—These are the narrow belts of forest along stream
banks, and are either intrusion of evergreen and other trees from a
lower latitude or the remnants of broader belts which have dwindled
to a mere fringe. Typical species are _Khaya senegalensis_, _Eugenia
guineensis_, _Adina microcephala_, _Diospyros mespiliformis_, etc.,
with a number of evergreen shrubs, typically Jasmines. The narrower the
belt the lower branched are the trees.
“KURIMI.”—This is the formation found in depressions, where there may
or may not be a stream, not necessarily flowing in the dry season. It
is an enlarged edition of the fringing belt and more nearly represents
the evergreen forest. Trees of large dimensions with long, clean
boles are found amidst a luxuriant undergrowth of shrubs and younger
trees, which if undisturbed will attain full maturity. “Kurimi” is
the chief source of timber in the Northern Provinces and from it such
type species as _Khaya grandifolia_, _Chlorophora excelsa_, _Albizzia
Brownei_, _A. fastigiata_, _Diospyros mespiliformis_, and frequently
Oil Palms are obtained.
“FADAMMA.”—This is represented by the broad river valley perennially
inundated, or a depression of varying size in flat country where water
lies during the rains. Typical species are _Mitragyne africana_,
_Paradaniellia Oliveri_ and _Borassus flabellifer_, the Fan Palm. There
is either a dense growth of grass or, in the case of temporary lakes,
an area of cracked mud.
Pure forests are rare in savannah and _Acacia Seyal_ and _Isoberlinia_
species are type cases. Gregarious clumps of various sizes are,
however, one of the commonest features and a large number of trees
is concerned. Examples are the _Acacias Seyal_, _arabica_, _albida_,
_Senegal_ and _campylacantha_; _Anogeissus_, _Isoberlinia_, _Bauhinia_,
_Anona_, _Bombax_, _Terminalia_, _Combretum_, _Detarium_, _Gardenia_,
_Parinarium_, _Pseudocedrela_, _Stereospermum_, _Ximenia_, _Uapaca_,
_Boswellia_, _Monotes_, etc.
Savannah also shows many examples of a dominant species, the presence
of which are indications of the composition of a forest. The presence
of this or that species sets a standard of comparative quality to an
area by which it may be valued from various standpoints.
Over wide areas of savannah there are to be found many evidences of
previous peoples in the shape of walled ruins, foundations of corn
stores, grindstones and heaps of hand-picked stones indicative of
cultivation. The dating of such remains gives the approximate age of
the forest growth, and from this evidence it would appear that certain
types of savannah deteriorate considerably with age and that farming
will regenerate them to a certain extent. A comparison of 20-30 year
old forest with the untouched older forest shows the former to be
denser, more healthy and of straighter and more even growth, while
the latter contains a large number of very old trees in a state of
decay, with great open crowns, liable to be blown down by storms, their
branches burned by fires and riddled with fungus. The new growth which
is to take their place consists mostly of grasses, stunted shrubs and
small trees of species which are incapable of forming a canopy. As
mentioned above, provided the area farmed is not too large, the support
given it by the surrounding forests is sufficient to ensure effective
regeneration, otherwise a poorer type takes hold.
In conclusion a short account of the growth and characteristics of
savannah forests is given. As would be expected, the trees, being
subject throughout life to extremely hard conditions, counter with
defensive measures for self-preservation. Most of them are prolific
seeders and many have the habit of retaining their fruits or seeds on
the tree for many months, sometimes right round to the next flowering
season. Germination of seeds is a matter of chance when the tree is
liable to ground fires from October to April or May. The life of a
seedling, too, is precarious, since at the age of six months it may
be subject to a devastating fire. In later life a fire, occurring
in April, may, if the grass is high, burn the bark to ashes on the
outside, destroying all fruits or seeds, killing the twigs and small
branches and apparently destroying all life. Yet, a month later
leaves will spring from all but the burnt tips, the tree losing a
year’s height growth, but in a position to put on another year’s stem
girth. Wounds on the trunk of a tree heal over with the formation of
a hollow or rotten core. Trees 4-5 feet in girth have been felled
and their stems found to consist of a mere shell two or three inches
thick. The hollow is filled either with the workings of termites or
the fermenting sap which is forced up from the ground level and will
pour out of the stump. Savannah trees are adapted to overcome most
of these adverse conditions. Heavy crops of fruit and seed, rapid
ripening of seeds or fire-resisting fruit coats and various means of
distribution are means to ensure germination. Deep or thickened tap
roots of seedlings are put down in the first year so that though the
seedling may be levelled by fire it will appear with renewed vigour
soon after. A very short flowering period for the individual tree is
a marked characteristic of many species. Fire has a quickening effect
on the flowering and leaf bearing of trees to a marked degree. A
grass fire in November may produce flowers and leaves in December on
trees which, if unburnt, would not have flowered till February. As a
rule, no tree will flower again if the first flowers have been burnt
off, though it will, of course, bear leaves. One or two exceptions,
very rare, have been noticed by the author, but these were due to the
peculiarity that some trees exhibit of bearing flowers on some of their
branches and not on others, so that the flowerless twigs were probably
excited by the fire into bearing flowers after it. Leaves are readily
replaced after attacks by locusts which generally take place early in
the season. The end of the cold weather and first sign of heat is the
spring of growth. Few trees have to wait for rain before they produce
all the signs of maturity except the complete growth of their leaves.
The bark of young seedlings, subject to fire, is very thick and corky
and that of old trees is still more so, while the inner layers are
fibrous and full of sap. Almost all species will coppice very well,
many throwing up shoots up to 10 feet high in a season, others only a
foot or two. Root shoots are also very common and a large number of
what are apparently seedlings in the forest are root shoots. Most trees
are anchored very firmly to the ground by lateral roots far longer than
the height of the tree, a protection against storms. A tree which is
completely ringed will often endeavour to join up the cut, meanwhile
continuing its season’s foliage, while the smallest connection with the
root is sufficient for it to live for many years. Most new leaves, as
a protection against the sun, are reddish in colour, many a brilliant
crimson, the green being produced through all gradations of colour
from the red. Others are hairy, scaly or covered with a bloom, the
protective coverings wearing off with maturity. The proportion of
sapwood to hard is large and many species show marked differences in
this proportion according to their locality, some showing no heartwood
in the north where it is produced in the south. The weights of woods
are often considerably heavier in the north than is the case for
the same species in the south. There are some localities where wide
areas are infested with termites to such an extent that, during the
dry weather their whole surface, even to the tips of the twigs, is
completely covered with the earth carried by the termites. Although
there are exceptions, it is observed that apparent damage is negligible
and that the old scales are removed from the bark, exposing the fresh
surface.
The savannah species are, then, well equipped to withstand fire,
drought, insects, wounds, storms, and damage by man and it can be
imagined how readily they will supplant better types, since the harder
the conditions the better adapted are the trees to meet them. The
wide distribution of most species renders them more aggressive, and
an individual species that will grow into a fine tree under the best
conditions can still grow under the worst, though it may differ in form
and feature so as to be hardly recognisable as the same species.
If, as it is supposed, savannah forests are depreciating of their own
accord, some factor other than climate, which has not been demonstrated
by records, must be at work. It is sufficient to point to the increase
and spread of the population from the towns to the forests to find a
reason for the displacement of good forest by lower grades. Shifting
cultivation encourages a worse type each time it is practiced and late
fires are very destructive.
For valuable assistance given in identifying the trees and shrubs in
this volume, the author is indebted to Dr. A. W. Hill, Director of the
Royal Botanic Gardens, Kew, and Mr. J. Hutchinson of the Herbarium. To
Dr. J. M. Dalziel he is indebted for the “Hausa Botanical Vocabulary,”
a valuable short-cut to further research. Other books referred to
are the “Flora of Tropical Africa” and Kew Bulletin, Additional
Series IX., neither of which has been used other than for purposes of
classification, it being the author’s aim to describe and illustrate
the material as it appears to be, and not only as it actually is from
the scientific point of view, avoiding botanical terms except where
they have no alternatives.
H. V. L.
_March_, 1925.
=ACACIA ALBIDA= Delile.—_Gawo_. LEGUMINOSAE.
This is the largest of the Acacias in the north, and attains a height
of over 60 feet with girths over 12 feet. It is particularly common in
Sokoto, but even there is locally distributed, and gregarious clumps
are commonly met with. It prefers dry, sandy soils. The form of the
young and the old tree is very different. The former has a straight
bole with acutely ascending branches forming a high, flat-topped crown
very similar to that of _Paradaniellia_ in shape. The bole may be clean
for over 20 feet, but in young trees there are usually clusters of
thorny twigs at no great height. As age increases the crown widens and
the limbs get heavier and more spreading until the form is like that of
_Parkia_. The bole is then quite clean and considerably thickened at
the base, the roots spreading above ground and forming flanges, thick
but of little height. Its distinguishing peculiarity is the habit of
shedding its leaves at the approach of the rains and putting them forth
at the first sign of the dry season, in September. It grows fast up to
full height and then slowly.
=The Bark= is uniform dull grey. Long wide fissures and prominent
ridges of hard bark ascend the bole and the bark appears as if it was
stretched without being cast off. Light brown patches, quickly turning
grey, are left by the falling scales. The slash is pale brown and
fibrous.
=The Thorns= are in pairs, under ½ inch long and slightly recurved.
They are pale brown with white bases. The young tree is armed all over,
but as the tree ages the thorns leave the stem and finally the higher
branches are free as if protection seemed to be unnecessary at a height.
=The Wood.=—The heartwood is a light, clean yellow. The sapwood is a
dirty white. Frequently the whole wood is a dirty white or grey, but
this is due to discolourations from mould and the wood should always be
seasoned in dry air and not allowed to get wet. In transverse section
the rings are indistinct and wide apart, the pores are small and evenly
distributed, mostly in festoons with twin pores here and there, the
soft tissue plainly seen as concentric lines with the hard tissue
alternating. The rays are extremely fine, very regular and closely
spaced and quite invisible to the naked eye. In vertical section there
are faint bands of colour, with light reflecting flecks in tangential
section. The wood is soft, very easy to work with all tools, seasons
well if looked after, and finishes well under the plane. The weight is
35 lbs. a cubic foot.
=The Leaves= are bipinnate, 4 inches long with 6-7 pairs of pinnae
bearing some 10-15 pairs of dusty, grey-green leaflets, covered with
tiny hairs. The foliage in the mass appears bluish-green. It appears
at the end of September and is susceptible to insect, caterpillar and
locust.
=The Flowers=, from October to December, are in dense spikes 3-4
inches long, scented. The lower inch of the spike is flowerless.
Several spikes are borne at the twig ends. Each flower has a 5-lobed
cream-coloured calyx with pink centre, 40-50 stamens, and a short
pistil with slightly clubbed stigma.
=The Fruits= are pods, at first green and sickle shaped, ripening to
a bright orange and twisting into strange shapes. They are 4-6 inches
long, 1 inch wide, concave on one side, convex on the other. They
contain dark brown shiny seeds ⅜ inch long. The pods ripen in January
and February and fall entire, rotting on the ground.
=Uses.=—Inferior canoes, of the stitched together type are made. The
ripe pods are collected and fed to cattle, sheep and goats. The common
brown kite nests frequently in its branches in March and April.
[Illustration]
=ACACIA ARABICA= Willd.—_Gabaruwa, Bagaruwa_. LEGUMINOSAE.
This tree, the original source of gum-arabic, is very common and widely
distributed throughout the north. It is very frequent round towns
where it is utilised for the tannin properties of its pods. It varies
largely in size from a small erect tree with umbrella crown to a large,
heavy-stemmed tree with high rounded crown. It occurs gregariously
in clumps or small forests, growing densely with the crowns meeting
overhead. The seed germinates freely in low-lying country liable
to submergence by rains or floods and the tree flourishes in such
situations. It is just as partial to dry sandy soils where it abounds.
With its almost black stem and branches, bluish-green foliage and
graceful, symmetrical form, it is readily distinguished from other
_Acacia_ species. The average height is some 20-25 feet, but trees over
35 feet with girths up to 8 feet are not uncommon.
=The Bark= is almost black, or a dull dark grey, with long stringy
ridges and narrow fissures. The dark colour extends to the branches and
woody twigs, the latter covered with a soft pubescence. A clear yellow
gum exudes from the slash which is a pale pink colour. The slash is red
brown and blackish in streaks.
=The Thorns= are in pairs on the branches and twigs, some quite short
and slightly curved, others, especially on the older wood being long,
straight, slender and very sharp, with a grey colour and a slight
backward slope. They are up to three inches in length and generally
curved a little.
=The Wood= is a deep red-brown with almost purple bands. The sapwood
is yellow. In transverse section the colour is darkest, the rings show
as dark, ill-defined bands, the pores are small, few and scattered
about between the fine straight rays which are visible against the
dark ground of the hard tissue. There are many double and nested pores
and zones with very few pores. Their contents nearly close them. In
vertical section the grain is twisted, there are dark bands and the
pores have black contents. The wood is very hard to saw and plane but
the finish is hard and takes a high polish. The grain picks up badly in
places. The transverse section will polish. The weight is 75-80 lbs. a
cubic foot.
=The Leaves= are bipinnate, some 2-4 inches long with 5-6 or sometimes
more pinnae bearing 15-20 pairs of leaflets with rounded tips, ³⁄₁₆
inch long. They are a dark bluish-green with grey bloom and soft
texture.
=The Fruits= are jointed pods, straight or sickle-shaped, with slightly
embossed seeds. The pod surface is wrinkled and covered densely with a
whitish bloom. The seeds, some 10-12 in a pod, are round, flattened,
shiny and brown, ⅜ inch in diameter. The pods, ripening towards the end
of the year, fall to the ground entire. They are the “Sant Pods” of
commerce.
=Uses.=—Hoe and axe handles are made from the wood which rarely reaches
large enough dimensions to provide canoes as it does in other parts of
Africa.
A concoction of the pods, crushed with water, is used for tanning. The
leaves, boiled, with the addition of a small piece of Tamarind pod, are
used as a cure for a disease of the eye which causes the lashes to fall
out.
From the pods a black leather dye called “kuloko” is made.
[Illustration]
=ACACIA CAMPYLACANTHA= Hochst.—_Kumbar Shafo, Farichin Shafo, Karo,
Karki_. LEGUMINOSAE.
A tall tree somewhat resembling _Acacia Sieberiana_, especially in the
case of full-grown trees of both species. A comparison of the bark,
thorns and pods will readily distinguish one from the other. It is
the tallest and most erect of the acacias in the north, reaching a
height of 60 or more feet and girths of 4-6 feet when growing, as is
very commonly the case, in dense clumps on stream banks, hillsides and
on the sites of old towns. This last peculiar situation is sometimes
explained locally by the fact that cattle eat the pods and deposit the
undigested seeds on the site of a cattle camp in a deserted town. The
bole is often 30 feet or more in length in these clumps, the crowns
high and flat-topped and meeting overhead, forming a density of shade
sufficient to kill all growth of grass on the floor. Old trees in the
open have lower, wider-spreading and more open crowns, with shorter
boles and bear a marked resemblance, at a distance, to _A. Sieberiana_.
They commonly reach over 6 feet in girth.
=The Bark= is a pale yellowish colour, sometimes almost white, and is
smooth, with small, regular, brownish scales which in old trees are
grey and coarser. The slash is crimson with white streaks, very fibrous.
=The Thorns=, which are the readiest means of distinguishing this
species from _A. Sieberiana_, are short, strong, recurved, and brown
with a black point. They resemble falcons’ claws, from which they get
their native name. They are in pairs at a widely obtuse angle.
=The Wood= is a very dark brown, with almost black streaks. The sapwood
is white. In transverse section the rings show as irregular dark bands,
the pores are small, few and connected by very thin lines of soft
tissue, the rays are very fine, waved and unevenly spaced, invisible
to the naked eye. In vertical section the rings show as bands of dark
brown and almost black and there are lighter areas. The wood is hard,
fibrous and bad to saw, not easy to plane, though the finished surface
is smooth and will take a good polish. The long fibres pick up badly in
places. The weight is 52 lbs. a cubic foot.
=The Leaves= are bipinnate, about 9-10 inches long with 20-25 pairs of
leaflets which droop on each side of the mid-rib. The narrow leaflets
are ³⁄₁₆ inch long, slightly curved and a dull, dark green.
=The Flowers= are in 4-5 inch spikes about ½ inch in diameter, densely
crowded with cream-coloured scented flowers with numerous stamens. They
appear from May-July in masses amongst the leaves.
=The Fruits= are pods, 4-5 inches long, ¾ inch wide, very flat, with
the seeds slightly embossed. They are very numerous, tenacious and
conspicuous on the trees from October onwards. The seeds, about six in
a pod, are round, flat, shiny and dark brown, the same colour as the
pods, and have strong germinating power.
=Uses.=—The wood is used for implement handles of all kinds. The
branches are cut for making protective farm fences, and the pods are
very much appreciated by cattle.
[Illustration]
=ACACIA DALZIELII= Craib.—_Gaba chara, Gwanno_. LEGUMINOSAE.
This is a slender Acacia, locally very plentiful, especially in central
and south-west Sokoto throughout some 1,000 square miles. It inhabits
the open bush savannah of better quality where the rainfall is good and
the soil contains some loam. In certain belts it is the predominant
species. It is the largest leaved of all the Acacias in this zone and
at a distance closely resembles _Entada sudanica_, though the leaflets
are much smaller and more numerous and the flowers and thorns are both
distinctive; in fact, the resemblance is one of form only. It grows
20-35 high with a girth up to 3 feet. Some trees are tall and slender
with high crowns, others low-branched and spreading, but the foliage of
all is very light and graceful.
=The Bark= is grey-brown with long fissures and large, shaggy scales
which fall in long, irregular sections. This is largely due to fires
which thicken and blacken the cork. The bark of the twigs is a silvery
grey. The slash is a dull red, exposing the orange colour of the wood.
=The Thorns= are in pairs on the twigs, the leaves springing from
between them. They vary considerably in size, ¼-¾ inch long, large and
green on the new shoots and small and black on the wood, as a rule.
They are slightly curved, and grooved along the inner side from the
point where the leaf-stalk springs.
=The Wood.=—The heartwood is reddish with long, vertical streaks of
black and brown in the pores. The sapwood is yellow with an orange
grain. In transverse section the rings are indistinct, the pores are
open and numerous, the soft tissue in wide and narrow festoons plainly
visible to the unaided eye. The wood is hard, splits easily, is
straight-grained, not easy to plane and weighs 65 lbs. a cubic foot.
=The Leaves= are 12-18 inches long, bipinnate with 20 or more pairs
of pinnae bearing 50 or more pairs of long, narrow, pointed leaflets
with parallel edges. Near the base on the dorsal side of the stalk is a
prominent oval gland. They are a very bright, fresh green, and at first
erect, finally spread and droop.
=The Flowers= are in large, erect panicles, 12-18 inches high and
stiffly branched, standing prominently up on the ends of the shoots.
They appear in the rains and are in bright yellow balls about ½ inch in
diameter.
=The Fruits= are pods, 3-5 inches long, ½-¾ inch broad, flat, dark
red-brown with a grey bloom and containing from 6-12 flat, oval, brown
seeds. The pod is slightly embossed at the seeds and very persistent,
numbers remaining on the tree till the following rains.
[Illustration]
=ACACIA NILOTICA= Del.—_Bagaruwa namiji_. LEGUMINOSAE.
This species is nearly allied to _Acacia arabica_ and can be at once
distinguished from it by the smooth, jointed pods. In other respects
it is very similar. The native distinguishes the two species by the
fruits, the _Acacia arabica_ with its large grey “sant pods” being
known as the female, “ta mata” as against the name “namiji” of _A.
nilotica_. As a rule this species is a much larger tree than _A.
arabica_ and two forms are commonly met with. The one, which is common
in low-lying country liable to inundation, has a short bole and a large
number of slender branches which ascend to a great height and spread
out wide, forming a large semi-spherical crown almost reaching the
ground. The other has a long bole with a girth of 10 feet or more and a
high rounded crown. The latter type yields a large volume of timber.
=The Bark= is almost black with deep fissures and very long, ragged
scales, which fall in large pieces. The slash is red-brown, with darker
streaks.
=The Thorns= are in pairs, quite small near the twig tips and up to 2
inches or more in length elsewhere, straight or curved, more often the
latter, white, slender and very strong and sharp.
=The Wood= is reddish-brown in colour, almost blood-colour in cross
section, with marked rings. It is very close grained, the cross section
being able to be planed quite smooth. The grain is irregular and picks
up. The weight is about 75 lbs. per cubic foot. See _A. arabica_.
=The Leaves= are 2-3 inches long with some five pairs of pinnae bearing
10-20 pairs of leaflets, bluish-green with a grey pubescence.
=The Flowers= are very numerous from February onwards in clusters
of 2-5 at the nodes, the slender stalks over an inch long and the
sweet-scented, yellow flower balls over ½ inch in diameter. As a rule
the ends of the twigs on which the flowers are borne have no spines,
these appearing later.
=The Pods= are very variable in size, up to 6 inches in length and
their peculiarity is the marked jointing which, before they are full
grown, gives them the appearance of a string of beads. They are smooth,
with a slight bloom and contain some 6-8 oval, flattened seeds which
ripen from March onwards.
=Uses.=—The wood is used for axe, hoe and tool handles.
[Illustration]
=ACACIA SENEGAL= Willd.—_Dakwora_. LEGUMINOSAE.
A small tree some 15-20 feet high on an average, which is commonly met
with in the more northerly provinces, especially in Sokoto, where it
grows in dense thickets. It branches low down and is often shrub-like
in its young stages, later producing a bole some 6 feet in length.
The branches, ascending at an angle of about 60 degrees, repeatedly
fork and form an open, flat-topped crown from which some of the long
straight twigs protrude some feet above. It is a source of gum-arabic.
=The Bark= of young trees is very light in colour with a creamy tint,
that of older trees, especially those which grow in the open, is purple
on the bole, with patches of the lighter tint here and there. All over
it are minute, whitish scales, so fine that they rub off in the hand as
a fine powder, like that of _Acacia Seyal_. Here and there, according
to season, are larger, thicker grey scales, chiefly about wounds or on
the swollen forks. The bark is very thin and if scratched with the nail
shows the bright green cambium layer just under the surface. The slash
is mottled red.
=The Thorns= are in threes at the swollen nodes. The centre thorn is
sharply recurved like a claw, the two side thorns being almost straight
and pointing forward towards the tip of the twig. All are short, very
sharp, with broad bases, like rose thorns, dark brown to almost black
in colour, with a greyish bloom.
=The Wood= is white, but of such small dimensions that it is not used.
=The Leaves= are bipinnate, 3-4 inches long, with some six pairs of
pinnae, each with some 20 pairs of leaflets, blue-green in colour and
paler below than above. The ribs are covered with very short hairs.
=The Flowers= which appear in April are in 3-4 inch long spikes, one or
two at the nodes. From ½-1 inch of the spike is flowerless, the rest
densely covered with small creamy-white flowers, each having a pale
green 5-lobed calyx, five pale green petals and a large mass of short,
white stamens with a pistil indistinguishable amongst them.
=The Fruits= are pods, varying in size according as they contain 1-6
seeds. They ripen in November and remain on the tree till April, often
a very heavy crop on the leafless tree. They are 1½-4 inches long and
an inch broad, flat, slightly shiny, embossed at the seeds, sometimes
the same width throughout, sometimes indented on the margin between
one seed and another, sandy in colour, with often blotches of a darker
colour. They split either whilst on the tree or fall entire and open
on the ground, the seeds remaining attached to each half alternately
and the two halves attached at the stalk. The seeds are round, flat,
green-brown, with a U-shaped scar on each side and attached to the pod
edge by a short, thick stalk. The pod is prominently cellular veined.
=Uses.=—The bark of the roots is twisted into ropes which are of great
strength.
[Illustration]
=ACACIA SEYAL= Del.—_Dushe, Dussa, Jimshi, Erafi, Gishishiya_.
“_Talh_.” LEGUMINOSAE.
This very common species is noted for its occurrence as pure forest
over large areas of country. It can be distinguished at a glance from
_A. Sieberiana_, which it resembles in small trees, by its powdery
orange or rust-coloured bark, or in the case of the variety _A.
fistula_, by the colour being a milky white. It is generally a small
tree from 15-30 feet in height, resembling _A. arabica_ in form, with
an umbrella-shaped or flat-topped crown formed by the ascending and
spreading branches. Sometimes the secondary branches are practically
horizontal and the crown wide and quite flat on the top. It bears a
profuse mass of bright yellow flower-balls, highly scented and very
conspicuous. It occurs in clumps or isolated examples on stony ground,
not in loose sand, but where the ground is broken up and barren looking.
=The Bark=, the most distinguishing feature, is powdery and comes off
in the hand with the appearance of minute flakes like bran. It is a
rust-red or orange colour and in the case of the variety _A. fistula_
the bark is green with the powder milk-white in colour. A clear white
or yellow gum exudes from the slash, which is light red and white, with
brown edges. _A. fistula_ is light red with green edges.
=The Thorns= are similar to those of _A. arabica_, but shorter, 1-2
inches long, white with black points, straight, strong and sharp and at
an angle of about 100° to each other. The base is frequently largely
swollen. Near the tips of the twigs little recurved thorns occur in
place of the long, straight ones.
=The Wood= is whitish, a brown colour being given it by the lines of
hard tissue. It is apt to discolour with mould. In transverse section
the close concentric rings of hard and soft tissue are very distinct,
the pores are very numerous in the bands of soft tissue of varying
width, the alternating bands of hard tissue being almost free of pores.
The rays are straight, the larger plainly visible, the finer often
closer together, showing as light-reflecting bands in radial section.
In tangential section the hard tissue makes a well-defined grain of
light brown. The wood is soft, the grain coarse; it works easily with
tools, the plane giving a rough finish. Weight 50 lbs. a cubic foot.
=The Leaves= are bipinnate, about 2 inches long with 6-8 pairs of
pinnae cut up into some 15 pairs of leaflets. There are typically three
in the angle of each pair of thorns and they are dark green when full
grown.
=The Flowers= are in yellow balls about ½ inch in diameter, 1-4 in the
axil of a leaf. They have 1½ inch stalks, are sweet scented and appear
from January onwards in masses which make the tree all yellow at a
distance. The young leaves appear just as the flowers are going.
=The Fruits= are slightly curved, flat, jointed, embossed pods, 3-5
inches long, light brown with green tinges and finely veined. When ripe
the pod splits up both edges, and the seeds, 6-10 in number, remain
fastened to the edges by the long twisted attachments, from which they
break loose gradually, the pod sections remaining attached to the
tree for some time before this occurs. Many pods fall with the seeds
still attached to them. The clusters of curved, split pods are most
conspicuous and they contract considerably during the ripening stages.
[Illustration]
=ACACIA SIEBERIANA= DC.—_Fara kaya, Bauji_. LEGUMINOSAE.
This common and widely distributed species has, when full-grown, some
similarity to _Acacia campylacantha_, especially when the species occur
in the open. Its long, white thorns distinguish it from the latter. It
is occasionally met with as pure forest, but should not be confused
with _Acacia Seyal_, the “Talh” acacia, which is very like the small
_A. Sieberiana_ and has yellow flower-balls and ochrey bark. Old trees
are a height of about 50 or more feet with girths of 5-6 feet. They
have large round crowns and sometimes rather persistent lower twigs,
though 20 feet boles are not uncommon. It grows well in dry situations
and frequently occurs, mixed with _A. Seyal_, in open, dry country.
=The Bark= of young trees is yellowish and smooth, this feature
persisting on the branches of older trees, which have rough, small,
square scales, grey in colour on the stem and larger limbs. The bark
exudes a gum which is white, clear and brittle when dry, making a fair
mucilage. The slash is yellow, with dark red edges.
=The Thorns=, persistent everywhere except on the bole and largest
limbs, are fine, straight and white, with very acute points. They are
in pairs at about 120° to each other, pointing slightly forward, up to
3 inches long. On new shoots they are green and soft, hardening as the
shoot ages. Quite small thorns are found at the tip of the shoots.
=The Wood= is a dull yellow colour, very subject to bluish
discolorations, due to mould. In transverse section the rings are
indistinct and inseparable from the numerous concentric lines of hard
and soft tissue which are clearly marked. The pores are open, very
numerous, of different sizes, the large ones plainly visible, mostly
single with little soft tissue, except along the rings where the pores
are in rows, each separated by a ray. There are a few double pores,
nests and small chains. The rays are slightly waved, fairly evenly
spaced except where the finer rays are closer together. The rays show
as light-reflecting bands in the radial section. The wood is soft,
rather coarse in grain, easily worked, planing to a rather rough,
untidy surface. The weight is 45 lbs. a cubic foot.
=The Leaves=, which spring from between the thorns, are bipinnate,
about 5-6 inches long with 10-25 pairs of pinnae, the numerous and dark
green leaflets being ⅛ inch long with rounded tips.
=The Flowers= are in white balls slightly over ½ inch in diameter, with
¾ inch stalks, in loose bunches. Their colour distinguishes them from
those of other species similar and likely to be confused. They are
sweet-scented and visited by bees.
=The Fruits= are large, brown pods, from 6-7 inches long, 1 inch wide
and ½ inch thick, straight or slightly curved. They are not very
numerous, but conspicuous by their size. The seeds, about 12 in number
are quadrangular, rounded, flattened, very hard and dark and light
brown.
=Uses.=—The young trees and the branches of the old are used for
handles of implements, the angle of branching being especially suited
to the shape of the large hoe (galma) handle.
The gum, in solution, is applied to turban and gown cloth and a sheen
produced by beating.
[Illustration]
=ADANSONIA DIGITATA= B. Juss.—_Kuka_. “_Baobab_.” MALVACEAE.
The Baobab tree is so well known as hardly to need description. The
enormous girth up to some 50 feet, large white flowers and pendulous
fruits are familiar. From its earliest years it assumes the shape, in
miniature, of the older trees. Though nature plays the largest part in
the shaping, the cropping of leaves for food, the stripping of bark for
rope and the ringing of large branches by beetles till they fall to the
ground, all help to accelerate the abnormal form. Widely distributed,
it is locally more than generally common, and abounds in groups. The
majority of large native towns are full of it. Occasionally it can be
seen without the usual stunted appearance, with slender branches and
well-formed crown. An association with _Tamarindus indica_ (Tsamiya) is
fairly common, the latter growing long slender stems about the former
and partly embracing its trunk.
=The Bark= is grey, with all shades of purple and a sheen. It has great
callus-growing properties and appears vigorously alive in its power to
cover up wounds. The outer bark is soft, spongy and full of sap, and
it is the inner layers which are stripped off for the rope making. The
slash is mottled red and white.
=The Wood= is not used. It is very light, soft and crumbling, rotting
rapidly under exposure.
=The Leaves= are digitate with some six or seven lobes, 2-3 inches
long, borne on a 4-5 inch leaf-stalk. They have sinuous margins and a
tongued tip; the mid-rib is sunken and the veins regular. The surface
is dark green above and smooth, but downy beneath. The leaves appear
soon after the flowers.
=The Flowers= are solitary and pendulous on 9-10 inch stalks, and
appear in May before the leaves. They are some 6-8 inches in diameter
with five leathery sepals covered densely on the inside with straight
hairs; five white petals nearly twice the length of the sepals,
recurved at the tip and with wrinkled edges; a stout, shiny, white,
tubular stamen column from which the mass of white stamens with light
brown anthers radiate and bend up towards the vertical position and
from which emerges the long shiny white pistil with spiral bend and
outward growth, bearing at its tip the flattened, lobed, sticky stigma.
All the flower parts tend to assume the vertical position. The Hausa
calls them “kumbali.”