The Orchid Flora of Benishangul-Gumuz (Western Ethiopia): An Ecological and Phenological Study

2007·2.9 MB·

by  Herrmann, Christof

Selbyana 28(2): 123-136. 2007.
THE ORCHID FLORA OF BENISHANGUL-GUMUZ
(WESTERN ETHIOPIA): AN ECOLOGICAL AND
PHENOLOGICAL STUDY
*
CHRISTOF HERRMANN,
Agency for Environment, Nature Conservation and Geology of Mecklenburg-Western Pomerania,
Goldberger Str. 12, D-18273 Giistrow, Germany.
Email: [email protected]
PHILLIP CRIBB, AND
Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE, U.K.
SEBSEBE DEMISSEW
The National Herbarium, Science Faculty, Addis Ababa University, P.O. Box 3434,
Addis Ababa, Ethiopia.
ABSTRACT. For the first time, the orchid flora of Benishangul-Gumuz (western Ethiopia, Wellega and
Gojam floristic regions) has been studied over a continuous period of more than two years. A total of 63
species has been recorded, of which twelve were new to Ethiopia, including one species new to science
(Disa facula P.I.Cribb, C.Herrm. & Sebsebe). This article presents the information on orchids gathered
during the study. It inclndes information on habitats, altitude ranges and flowering time, abundance and
distribution. Characteristics of the orchid diversity of the region and threats due to land use changes are
also described.
Key words: Orchidaceae, new records, Benishangul-Gumuz National Regional State (BGNRS), western
Ethiopia, habitats, threats
INTRODUCTION cies of vascular plants have been collected and
described in recent years, and numerous species
Due to its remoteness and poor accessibility, new to Ethiopia have been found (Cribb et al.
the result of bad road conditions and decades of
2002, Nordal & Sebsebe Demissew 2002, Seb
military conflict, western Ethiopia is, in botani
sebe Demissew et al. 2003, Sebsebe Demissew
cal terms, still poorly understood. At the same
& Nordal 2004, Sebsebe Demissew et al. 2005).
time, the area is of great scientific interest: the
The knowledge of the flora of this region was
western escarpment of Ethiopia represents an
considerably enhanced when one of the authors
identifiable vegetation unit, which was classified
(Herrmann) was able to explore the vicinity of
by White (1983) as "Undifferentiated wood
Assosa continuously over a period of more than
lands (Ethiopian type)" (unit no. 29b on his
two years. Further records and collections of
vegetation map of Africa). Friis and Sebsebe
plants were made from other areas, which were
Demissew (2001) characterized the same area as
occasionally visited during field trips. Since
"Combretum-Terminalia deciduous woodland
and savannah vegetation"; however, later on these areas are confined to different altitude
they considered the concept of White (1983) as ranges, some other orchid species which do not
more appropriate (Sebsebe Demissew et al' occur around Assosa were recorded. However,
2005). the visits to these areas were rather short and
These woodlands stretch along the Sudanese only during specific seasons. Even more species
border from Kefa in the south to Eritrea in the might be found if these areas were investigated
north, forming a belt along the escarpment of over the whole year.
the Western Plateau at an altitude range from The article presents the information on or
(500) ... 900 to 1900 m a.s.l. Although the re chids gathered during the two years' study. It
gion is poorly explored, existing results indicate includes information on habitats, altitude ranges
an interesting and partly unique flora with a high and flowering time, abundance and distribution
proportion of endemic species. Several new spe- of a total of 63 species. Furthermore, character
istics of the orchid diversity of the region are
* Corresponding author. also described.
123
124 SELBYANA Volume 28(2) 2007
about 75%-is lowlands (kolla, below 1500 m
a.s.l.). Twenty-four percent are midlands (woyna
Ethiopia
dega, 1500-2500 m), and only 1 % are highlands
(dega, above 2500 m).
Hydrography
Benishangul-Gumuz is crossed by the Blue
Nile, which enters the region from the east, turn
ing then to the north-west and leaving it between
Sherkole and Guba Woreda towards the Sudan.
Major tributaries to the Blue Nile are the Dabus,
Didessa, and Beles rivers.
The western and northwestern parts of Be
nishangul-Gumuz (Kurmuk, Sherkole, Guba,
and parts of Dangur Woreda) are characterized
by low availability of surface water, especially
MAP 1. The geographic location of Benishangul during the dry season when the smaller water
Gumuz within Ethiopia.
courses become dry.
In the Assosa-Bambesi area, the situation is
quite different, with many small creeks and riv
LOCAn ON AND NATURAL
ers forming an extensive network of permanent
CHARACTERISTICS OF THE STUDY AREA
water courses.
Lakes do not exist in the region. During the
Location
rainy season some depressions fill with precipi
Benishangul-Gumuz National Regional State tation water, forming temporary or even per
(BGNRS) is one of the new Federal States es manent pools.
tablished by the Ethiopian Constitution in 1994.
With regard to the floristic regions, as estab Climate
lished by the "Flora of Ethiopia and Eritrea"
(which refer to the former administrative re The climate of the region is characterized by
gions), the southern part of BGNRS belongs to a unimodal rainfall pattern (i.e., a single rainfall
Well ega, and the area north of the Blue Nile to maximum per year). Unimodal rainfall regimes
Gojam. are characteristic for the whole of western Ethi
BGNRS is situated in western Ethiopia (Map opia.
1), extending along the Sudanese border be The duration of the rainy season decreases
tween 08°47' and 12°04'N. The western and from south to north. According to the classifi
eastern limits are the longitudes 34°06' and cation of rainfall regimes given by NMSA
37°02'E, respectively. The neighboring region to (l996a), Benishangul-Gumuz lies in the zone
the north and northeast is the Amhara Region, b2, which is characterized by a wet season from
to the south and southeast the Oromiya Region. April/May to October/November. Beside the lat
The total area of BGNRS amounts to about itude, the altitude has a considerable influence
50,380 km2. The region is divided by the Blue on the amount of precipitation, which increases
Nile. The northern part-Metekel Zone and with increasing altitude (FIGURES 1, 2). Thus,
Pawe Special Woreda-comprises an area of Assosa, at an altitude of 1550 m, has an average
26,560 km2, the southern part-Assosa Zone, annual precipitation of 1275 mm, whereas Kur
Kamashi Zone, and Mao-Komo Special Wore muk, at an altitude of 700 m, only receives 860
da-23,820 km2• mm rainfall (NMSA 1996b).
The region is divided into 20 major adminis The temperature reaches a daily maximum of
trative units called Woredas, including two Spe 20-25°C in the rainy season and rises to 35-
cial Woredas (Pawe and Mao-Komo) (Map 2). 40°C in the dry season. The hottest period is
from February to April. The minimum temper
Topography and Altitude Range atures range from 12°C to 20°C, depending on
season and altitude.
The elevation ranges from 580 m to 2731 m
a.s.!. with the highest peak being the Belaya pla
Vegetation Cover
teau in Dangur Woreda, while the lowest area is
where the Blue Nile crosses the Ethiopian/Su The western escarpment of Ethiopia repre
danese border. The major part of the region- sents a recognizable vegetation unit, which was
HERRMANN ET AL.: THE ORCHID FLORA OF BGNRS 125
34°30' 35°00' 35°30' 36°00' 36°30' 37"00'
Legend
D Regional boundary
D Woreda boundaries
Woreda administrative
• centres f major towns N
A
NRoads
N
Major rivers
b
P
b
P
o
b
P
~
20 40 60 80 100 Kilome ers
34°30' 36°00' 36°30' 37"00'
MAP 2. Overview map of Benishangul-Gumuz.
classified by White (1983) as "Undifferentiated Combretum-Terminalia woodlands are the
woodlands (Ethiopian type)" (unit no. 29b on main vegetation type of BGNRS. They occur be
his vegetation map of Africa). Friis and Sebsebe tween 500 and 1900 m a.s.l. and with a rainfall
Demissew (2001) described the vegetation of of 800 to 1400 mm per year. Dominant species
this transition area between the Ethiopian high are Terminalia brownii, Combretum molle, Cel
lands and the Sudanese lowlands as "Combre tis ajricana, Croton macrostachyus, Milletiajer
tum-Terminalia deciduous woodland and Savan ruginea, Ekebergia capensis, Syzygium gui
nah zone;" however, later on they considered neense, and Ficus spp. (UNECA 1998).
the concept of White (1983) as more appropriate The vegetation cover of the region is not ho
(Sebsebe Demissew et al. 2005). BGNRS lies mogenous, however. Lowland bamboo (Oxyten
almost entirely within this vegetation zone. anthera abyssinica) is another dominant natural
126 SELBYANA Volume 28(2) 2007
Monthly precipitation Temperature (Assosa)
30°Tr======~-----------------------' 24,-------------------------------,
-+-Assosa 0'
E 250 -):-Bambesi ----- E.... 23
.s 200 ~__8_e Kguirm uk 1~~;; 22
oc [ 21
:; 150 E 20
:~ 100 ~8, 19
0~. 50 ~~ 18 ---.-----.--------- -----.---------.-------
o~~~~~~~--------~--~~
Jan Feb Mar Apr May Jun Ju! Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Month
Month
FIGURE I. Monthly rainfall pattern of selected sites FIGURE 3. Average temperature of Assosa. (Data
in Benishangul-Gumuz (Data from NMSA 1996b). from NMSA 1996b.)
ture, and lower exposure to the sun provide the
Cumulative annual precipitation
required conditions for many orchid species, es
1400 -+-Assosa ----------------------- --------------- pecially epiphytes.
E 1200 -):-Bambesl Other forest types occurring in the region are
.§. 1000 .........-Beg!
co: 800 --Kurmuk dense forests (with Hagenia abyssinica, Juni
~ perus procera, Podocarpus falcatus, Olea eu
0. 600 --
"2 ropaea subsp. cuspidata, and Prunus africanus
400
Q: as dominant species), Acacia woodlands, and
200
Boswellia woodlands (UNECA 1998). However,
Jan Feb Mar Apr May Jun Jut Aug Sep Oct Nov Dec the orchid flora of these forest types could not
Month be studied.
L---~~ __~ _________________________ ' A characteristic feature for the western Ethio
FIGURE 2. Cumulative annual precipitation of se pian woodlands is their exposure to fire. The
lected sites in Benishangul-Gumuz (Data from NMSA
herbal biomass is annually burnt by the local
1996b).
population during the dry season (December
March). This practice does not seem to harm the
forest vegetation; the plants show clear adapta
component of the woodland vegetation between
tions to fire.
(700) ... 1000 to 1800 m a.s.l. It requires a min
Although most of Benishangul-Gumuz is still
imum annual rainfall of more than 700 mm and
covered by natural forests, a considerable pro
grows on poor soils. Its occurrence is restricted
portion of the region has been transformed to
to the western part of Ethiopia, but it emerges
cropland and pastures, especially in the areas
also in the savannah woodlands of Sudan. The
with higher population density (Assosa-Bam
Oxytenanthera abyssinica thickets often form a
besi area, Pawe, Bulen, and Dibate). The pas
mixed pattern with Combretum-Terminalia
tures are usually characterized by the presence
woodlands. The total area of bamboo thickets in
of bushes and single trees. Often shallow soils
Benishangul-Gumuz is actually estimated at
over rocks, which are not arable, are used for
440,000 ha (UNECA 1998). The largest bamboo
grazing. These bushy meadows are the habitat
thicket is the Anbessa Chaka ("Lion Forest")
for a number of orchid species.
between Assosa and Bambesi.
Of crucial importance for the region's orchid
Large areas of lowland bamboo have been de
diversity are different types of wetlands:
stroyed in the Assosa-Bambesi area starting in
1984/85, when more than one hundred thousand a. Permanent wetlands: These wetland types
settlers from Wello were brought to this part of occur where ground water emerges on the
the region. The settlers cleared major parts of slopes or at the foot of the hills. Quite often
the natural vegetation cover for crop cultivation they are found adjacent to small creeks and
and cattle breeding. The destruction continues rivers, where, during the rainy season, they
due to the extraction of wood for construction may be reached by flood water from the river,
and fuel purposes. but the main permanent water supply comes
Riverine forests are found along the perma from groundwater outlets. The wetlands are
nent or seasonal water courses of the region. Al supplied with water all year round, although
though they do not extend over large areas, they during the dry season the water level is rel
are very important for the biological diversity of atively low. They are found mainly in the As
the region. Higher air moisture, lower tempera- sosa-Bambesi area.
HERRMANN ET AL.: THE ORCHID FLORA OF BGNRS 127
h. Seasonal wetlands: These wetlands are the Other areas were visited during field work. A
flood plains. They are found in the valleys of three-week visit to Kamashi zone (Kamashi,
some larger rivers. They become flooded an Agelo Meti, and Belo Jegonfoy Woredas) in
nually during the rainy season, but dry up June 2001 resulted in records and collections of
during the dry season. Some important flood a considerable number of orchid species, includ
plains are found along the Dabus river east ing several species which obviously do not oc
of Bambesi, and the Keshmando river, about cur in the Assosa area. Some of them were new
20 km south of Bambesi. for Ethiopia. However, it must be mentioned that
c. Temporary and permanent pools: These the records and collections from Kamashi zone
wetlands are formed in depressions of rocks represent only one seasonal aspect; species with
or heavy soils with low drainage capacity. a flowering period later in the rainy season (e.g.,
They are filled with rainwater during the all Habenaria species) are not represented in the
rainy season. During the dry season, they dry records and collections from this area.
out completely or become considerably re The lowland areas of BGNRS « 1000 m, e.g.,
duced in size. However, quite often some wa Guba, Sirba Abay, Menge, Sherkole, and Kur
ter or at least mud remains until the new rains muk Woreda) were visited only during the dry
start to fill the pool again. These wetland ar season and at the very beginning of the rainy
eas may extend over surfaces of 0.5-5 hect season, i.e., from November to May. Hence,
ares. They are found around Assosa and only very few orchids were recorded. The areas
along the road Bambesi-Begi. are inaccessible during the rainy season. They
provide climatically different conditions in com
In the hot and dry lowland areas (below 1200
parison to the Assosa-Bambesi (1300-1600 m
m; e.g., Kurmuk, Sherkole, Sirba Abay, and
a.s.l.) and Kamashi areas (1000-1300 m a.s.l.),
Guba Woreda) no permanent wetlands are
being hotter and drier. During the dry season
found.
hardly any water can be found. Wetlands, which
form important orchid habitats in the higher
MATERIAL AND METHODS zones, are not found in the lowlands.
The higher areas of the region, above 2000 m
Every orchid species found was collected, (the Belaya plateau in Dangur Woreda and some
identified, and pressed. Identification was done areas in Wembera Woreda), could not be visited.
with the keys given in volume 6 of the "Flora Therefore, it must be emphasized that the results
of Ethiopia and Eritrea" (Cribb & Thomas presented here give a reasonably comprehensive
1997). All specimens collected were handed picture for the 1300-1500 m altitude range of
over to the National Herbarium of Ethiopia, Ad the Assosa-Bambesi zone, but not for the whole
dis Ababa University. Species not included in region. The discovery of more species can be
volume 6 of the "Flora of Ethiopia and Eritrea" expected if the lowland and highland zones are
(i.e., new species records for Ethiopia) were sent studied in detail.
for identification via the Addis Herbarium to one
of the authors (Cribb), at the Royal Botanical
RESULTS
Gardens, Kew.
Geographical position and altitude range of Species Records
the collection site were determined with GPS
(Garmin 12). However, it has to be mentioned A total of 63 orchid species from 16 genera
that the altitude measurements are rather ap were recorded, of which twelve species were
proximate. Especially those taken before May new to Ethiopia, including one species new to
2000, when GPS signals still were scrambled for science (Disafacula, P.J.Cribb, C.Herrm. & Seb
military reasons, may be of rather low accuracy. sebe 2002). The orchids recorded in Benishan
In case of doubtful readings, the contour lines gul-Gumuz thus account for the majority of the
of topographic maps 1 :50,000 were used for species recently added to the "Flora of Ethiopia
comparison. In addition to the collections, in and Eritrea." From the appearance of volume 6
formation on species, date, habitat, geographical of the "Flora of Ethiopia and Eritrea" in 1997
position, and altitude was recorded for all or to the publication of the "Field Guide to Ethi
chids found in the field. opian Orchids" (Sebsebe Demissew et al. 2004),
The main study area was the vicinity of As the number of orchid species known for Ethiopia
so sa, up to a distance of about 20 km around increased from 154 to 171; eleven of the 17 new
the town. During two dry and almost three com species were found in Benishangul-Gumuz. An
plete rainy seasons, each different habitat was other new species (Polystachya aff. albescens
regularly (usually every weekend) searched for subsp. imbricata) collected in Benishangul-Gu
orchids and other monocotyledonous plants. muz has not been considered by Sebsebe De-
128 SELBYANA Volume 28(2) 2007
missew et al. (2004) since the specimen was too vata, the Nervilia spp.). Furthermore, there are
poor for positive identification. some species which can occur on dry sites as
The new species from Benishangu1-Gumuz well as on wetlands (e.g., Eulophia cucullata).
belong to the genera Habenaria (2), Disa (3), Among the epiphytic species, there are those
Polystachya (1), and Eulophia (6). which occur exclusively in shady places in riv
The total number of orchid records (collec erine forests, characterized by higher air mois
tions and sight records) was 440. The data gath ture and lower temperature, and those which
ered provide information about flowering time, also occur on single trees in open meadows with
habitat requirements, distribution, and abun strong exposure to sun and wind (e.g., Calyptro
dance. This information is summarized in the chilum christyanum, Polystachya steudneri). TA
species list in the appendix. BLE I gives a summary of the ecological groups
An examination of the collections from the of the orchids found in Benishangul-Gumuz.
National Herbarium in Addis Ababa showed that
there are very few previously noted orchid re Threats
cords from the western parts of Well ega and Go
jam floristic regions. The herbarium material did The main threat to the orchid diversity of
not include orchid species from the territory of BGNRS is the drainage of wetlands. One third
BGNRS prior to the present study. However, two of the species found are restricted to wetland
species not yet found in BGNRS have been col areas and would disappear if the wetlands were
lected in neighboring areas of Oromiya (formerly destroyed. Wetland areas are very limited in ex
western Wellega): Polystachya rivae Schweinf. tension and also in distribution. They are rela
(Mooney 6878, collected near Dembi Dolo, alt. tively common in Assosa and Bambesi Woredas
1920 m, 05 March 1957), and Polystachya ben and do also exist to a limited extent in Kamashi,
nettiana Rchb.f. (Mooney 6915, collected near Agelo Meti, and Belo Jegonfoy Woredas. They
Bube, alt. 1980 m, 08 March 1957). The collec do not exist in the vast areas of lowlands below
tion sites are situated about 90 and 50 km south 1000 m. Unfortunately, the area with the main
of BGNRS, respectively. occurrence of wetlands-Bambesi and Assosa
Woredas-is also the area with the highest ex
Orchid Habitats tension and intensity of crop production. This is
a result of the settlement program of 1984/85,
Three ecological groups can be distinguished: when more than one hundred thousand farmers
from the famine-stricken area in Wello were
1. Wetland species (i.e., orchids which are
brought to Benishangul-Gumuz. The Wello
strictly confined to wetlands)
farmers knew how to control the water supply
2. Species of open bush- and woodland (Com
of wetlands in order to cultivate all the year
bretum-Terminalia wood- and bushlands),
round. In particular, the spring water outlet areas
grazed grasslands or semi-open places of Ox
along rivers and creeks are supplied with drain
ytenanthera abyssinica thickets
age and irrigation channels, plowed, and seeded
3. Epiphytic species.
with crop plants. These drainage and irrigation
The wetlands of Benishangul-Gumuz consist of: systems are a clear advantage for the farmers,
who can produce during 12 months and thus im
1. Spring water outlets on hill slopes, especially
prove their livelihood; they are also an important
on the bottom of river valleys (e.g., wetlands
benefit for the local population, since they pro
along the Selga river, wetland near Ura, wet
vide fresh fruits and vegetables (such as carrots,
lands in the Hoha valley); the soil is wet all
lettuce, tomatoes, bananas) for the local markets
year.
from November to April. However, since a ma
2. Flood plains of larger rivers (Dabus, Kesh
jor part of the wetlands has already been trans
mando); these wetlands fall dry during the
formed to cropland, an important orchid habitat
dry season.
is becoming more and more reduced and could
3. Pools; these are depressions of usually 0.5-5
even be lost in the near future. During the time
hectares without drainage, which fill with
of the study, a continuous decline of wetlands
precipitation during the rainy season, recede
around Assosa was observed. Some wetlands
during the dry season, but usually remain wet
with very high orchid diversity were destroyed,
to some extent all the year round.
among them the Selga wetlands 2 km NE of
Among the species of open bush and wood Assosa (15 species on only two hectares, the
lands, there are species which usually occur in only place where Disa hircicornis has so far
places with high light exposure (most species) been found in Ethiopia!). For this reason, a con
and others that prefer stronger shade (Eulophia servation program for wetlands in Benishangul
guineensis, Habenaria egregia, Habenaria cla- Gumuz is urgently needed. This conservation
HERRMANN ET AL.: THE ORCHID FLORA OF BGNRS 129
TABLE 1. Number of orchids found according to habitat types.
Species of open bush-and Epiphytic species
woodland. grazed grassland. and
Oxytenanthera abyssinica thickels Riverine forests and Epiphytes on trees in
Wetland other rather shady open areas with
Genus species Open places Shady places and moist places higher exposure
Aerangis Rchb.f.
Angraecopsis Kraenzl.
Brachycorythis Lindl. 2
Bulbophyllum Thouars 2
Calyptrochilum Kraenzl.
Cyrtorchis Schltr.
Diaphananthe Schltr.
Disa Bergius 3 1
Eulophia Lind!. 7 6 3
Habenaria Willd. 9 8 3
Microcoelia Lindl.
Nervilia Gaudich. 3
Platycoryne Rchb.f.
Polystachya Hook. 3
Pteroglossaspis Rchb.f. 1
Satyrium Sw. 1 2
Total 21 21 9 10 2
program should respect the needs of the farmers The Combretum-Terminalia woodlands as
for income sources and of the population for well as the Oxytenanthera abyssinica thickets
fresh fruits and vegetables, but it should also are also largely reduced due to the needs for
provide protection for a certain proportion of the cropland and firewood, especially in the area of
most diverse and valuable wetlands. the settlement program around Assosa and Bam-
FIGURE 4. Wetland with Habenaria zambesina in the Hoha river valley, 13 km N of Assosa. Photograph: C.
Herrmann 1999.
130 SELBYANA Volume 28(2) 2007
FIGURE 5. Transformation of wetlands into croplands: The loss of habitat is a major threat to the orchid
diversity of BGNRS. Photograph: C. Herrmann 2001.
besi. However, these habitats still cover exten NMSA-National Meteorological Services Agency of
sive areas. Woodlands on shallow and rocky Ethiopia. 1996a. Climatic and Agroclimatic Re
soils are hardly attractive for crop production. A sources of Ethiopia. Meteorological Research Re
port Series. Vol. 1. No 1, Addis Ababa.
certain proportion of this woodland is trans
NMSA-National Meteorological Services Agency of
formed to pastures, which are usually covered
Ethiopia. 1996b. Climate Classifications of Ethi
with scattered trees and bushes. Many of the
opia. Meteorological Research Report Series. Vol.
woodland orchids still find adequate living con 1. No 3, Addis Ababa.
ditions in these grasslands. Woodlands and bam Nordal, I. and Sebsebe Demissew. 2002. Crinum bam
boo thickets as well as pastures are annually ex busetum, a new species of Amaryllidaceae from
posed to controlled fires. Between December North East Africa. Kew Bulletin 57: 465-469.
and March, the local population burns the excess Sebsebe Demissew, I. Nordal, and O.E. Stabbetorp.
biomass of these habitats. However, this tradi 2003. Flowers of Ethiopia and Eritrea: Aloes and
tional practice reportedly has been employed for other Lilies. Sharna's Nature Series, Addis Ababa.
centuries. Although it should have an effect on Sebsebe Demissew and I. Nordal. 2004. Pancratium
centrale (=Mizonia centralis)-a rare Central Af
the vegetation composition, the actual "natural"
rican species discovered in Ethiopia. Kew Bulletin
vegetation seems to have adapted.
59: 117-121.
Sebsebe Demissew, P.J. Cribb, and R Rasmussen.
LITERATURE CITED 2004. Field Guide to Ethiopian Orchids. Royal
Botanic Gardens Kew, UK.
Cribb, P.J., and S. Thomas. 1997. Orchidaceae. pp. Sebsebe Demissew, I. Nordal, C. Herrmann, I. Friis,
193-307 in S. Edwards, T. Mesfin, and I. Hedberg, Tesfaye Awas, and O. Stabbetorp. 2005. Diversity
eds. Flora of Ethiopia and Eritrea, Vol. 6. Addis and endemism of the western Ethiopian escarp
Ababa and Uppsala. ment-a preliminary comparison with other areas
Cribb, P.J., C. Herrmann, and Sebsebe Demissew. of the Hom of Africa. BioI. Skr. 55: 315-330.
2002. New reeords of Orchids from Ethiopia. UNECA-United Nations Economic Commission for
Lindleyana 17(4): 178-188. Africa. 1998. Forestry Programme Proposal, Ben
Friis, I. and Sebsebe Demissew. 2001. Vegetation shangul Gumuz National Regional State, Volume
maps of Ethiopia and Eritrea-a review of exist VI, joint report of UNECA and the National Re
ing maps and the need for a new map for the Flora gional Government of Benishangul-Gumuz,
of Ethiopia and Eritrea. BioI. Skr. 54: 399-439. UNDPIECA Project ETH 94/01/01/99.
HERRMANN ET AL.: THE ORCHID FLORA OF BGNRS 131
White, E 1983. The Vegetation of Africa: A Descrip 5. Habenaria bracteosa A. Rich.
tive Memoir to Accompany the UNESCO!A ET
Found on several sites around Assosa, locally
FATJUNSO Vegetation Map of Africa. UNESCO,
abundant; Habitat: swampy meadows along riv
Paris.
ers and creeks; Altitude: 1450-1550 m; Flow
ering time: July-August; Collection: C. Herr
ApPENDIX: LIST OF ORCHID SPECIES mann 17
RECORDED IN BENISHANGUL-GUMUZ, 6. Habenaria filicornis A. Rich.
INCLUDING INFORMATION ON HABITATS,
Common around Assosa and at the Keshman
ALTITUDE RANGE AND FLOWERING TIME
do marsh; Habitat: open grasslands with scat
Note: The collections are kept in the National tered bushes and swampy meadows along rivers
and creeks; Altitude: 1370-1570 m; Flowering
Herbarium, Addis Ababa University, Ethiopia.
time: July-September; Collection: C. Herr
Some duplicates are kept at the Royal Botanic
mann 9
Gardens, Kew, UK.
Section Commelynifoliae Kraenzl.
Brachycorythis Lindl.
7. Habenaria platyanthera Rchb.f.
1. Brachycorythis pubescens Harv. Found around Assosa, recorded at only three
locations; Habitat: swampy meadows along riv
Found around Assosa and at Keshmando
ers and creeks; Altitude: 1490-1550 m; Flow
marsh, usually occurring as single plants or
ering time: July-September; Collection: C.
groups of few plants; Habitat: grassland with
Herrmann 38
scattered bushes and open woodlands, semi
8. Habenaria peristyloides A. Rich.
open places in Oxytenanthera abyssinica thick
ets, road sides, occasionally also in temporarily Found around Assosa, locally abundant; Ha
wet areas (areas that are wet at the end of the bitat: swampy meadows along rivers and
rainy season, but not all year); Altitude: 1370- creeks; Altitude: 1430-1500 m; Flowering
1575 m; Flowering time: July-August; Collec time: July-September; Collection: C. Herrmann
tion: C. Herrmann 3 18
9. Habenaria zambesina Rchb.f.
2. Brachycorythis buchananii (Schltr.) Rolfe
A very common orchid, found on almost ev
Recorded around Assosa (Selga river, some ery wetland around Assosa, often in high den
small creeks S of Assosa), and near the road sity; also recorded at the Keshmando marsh and
Bambesi-Begi 20 km S of Bambesi; Habitat: near Kamashi; Habitat: swampy meadows
wetlands, damp areas; Altitude: 1370-1550 m; along rivers; spring water outlet areas on hill
Flowering time: July-September; Collection: slopes; Altitude: 1280-1560 m; Flowering
C. Herrmann 13 time: July-August (beginning of September);
3. Brachycorythis ovata Lindl. subsp. Collection: C. Herrmann 12 & 31
schweinfurthii (Rchb.f.)
Section Multipartitae Kraenzl.
Found at one location only, in Anbessa Chaka 10. Habenaria aethiopica S.Thomas &
half way between Assosa and Bambesi; the spe P.J.Cribb
cies starts flowering at the beginning of the rainy
Found at only one location, about 1 km S of
season in May, Le., earlier than the other two
Ura (12 kIn NE of Assosa); Habitat: wet
species of the genus; Habitat: an open transition meadow; Altitude: 1430 m; Flowering time:
area between a wetland and Combretum-Termin July-beginning of August; Collection: C.
alialOxytenanthera abyssinica woodland; Alti Herrmann 29 & 151
tude: 1500 m; Flowering time: May-beginning
11. Habenaria egregia Summerh.
of July; Collection: Sebsebe D., C. Herrmann &
Tesfaye A. 6021 A new record for Ethiopia; found on Inzi
mountain near Assosa and in Anbessa Chaka
between Assosa and Bambesi; Habitat: shady
Habenaria Willd.
places on a meadow with scattered bushes and
Section Chlorinae Kraenzl. Acanthus; Oxytenanthera abyssinica thicket;
Altitude: 1450-1550 m; Flowering time: June
4. Habenaria distantiflora A. Rich. July; Collection: C. Herrmann 124, 125 & 239
Found only once about 1 km S of the village
Section Pentaceras (Thouars) Schltr.
Ura, about 12 km NE of Assosa; Habitat: wet
meadow; Altitude: 1430 m; Flowering time: 12. Habenaria malacophylla Rchb.f.
July; Collection: C. Herrmann 142 Found only in Anbessa Chaka between As-
132 SELBYANA Volume 28(2) 2007
sosa and Bambesi; Habitat: Oxytenanthera Flowering time: July-beginning of August;
abyssinica thicket; Altitude: 1510 m; Flower Collection: C. Herrmann 145
ing time: September; Collection: C. Herrmann
20. Habenaria cirrhata (Lindl.) Rchb.f.
161 & 162
A rare species, found 3 km SW of Assosa and
Section Replicatae Kraenzl. in Anbessa Chaka between Assosa and Bambesi;
Habitat: meadows with scattered trees and
13. Habenaria chirensis Rchb.f.
bushes; Oxytenanthera abyssinica thicket; Alti
Found along the Dabus and Keshmando tude: 1510-1575 m; Flowering time: July;
rivers, and near Komesha, but not recorded on Collection: C. Herrmann 145 & 243
wetlands around Assosa; Habitat: wet meadows
along rivers, damp grasslands of spring water Section Macrurae Kraenzl.
outlet areas; Altitude: 1300-1400 m; Flowering
21. Habenaria perbella Rchb.f.
time: July-September; Collection: C. Herrmann
6 & 163 Rare, found on only one site 2 km S of As
sosa; Habitat: meadows with scattered trees and
14. Habenaria schimperiana A.Rich.
bushes; Altitude: 1530 m; Flowering time:
A very common species around Assosa; July; Collection: C. Herrmann 244
Habitat: meadows with scattered bushes and
rock outcrops, swamp meadows; Altitude: Section Diphyllae Kraenzl.
1430-1600 m; Flowering time: July-beginning
22. Habenaria vaginata A.Rich.
of September; Collection: C. Herrmann 19 & 20
Found around Inzi Mountain near Assosa and
15. Habenaria humilior Rchb.f.
in Anbessa Chaka between Assosa and Bambesi;
A very common species around Assosa; Habitat: on shallow soils in meadows with scat
Habitat: open grassland, bushed meadows and tered trees and bushes; Oxytenanthera abyssini
meadows with rock outcrops; also on swampy ca thicket; Altitude: 1510-1600 m; Flowering
meadows; Altitude: 1430-1600 m; Flowering time: June-July; Collection: C. Herrmann 120
time: July-beginning of September; Collection: & 240
C. Herrmann 21, 22 & 23
Section Trachypetalae Summerh.
16. Habenaria ichneumonia (Sw.) Lindl.
23. Habenaria longirostris Summerh.
A common species around Assosa; also near
Kamashi; Habitat: swampy meadows, damp A new record for Ethiopia; found at three
grasslands; Altitude: 1280-1560 m; Flowering places in the Assosa area; Habitat: meadows
time: June-September; Collection: C. Herrmann with scattered trees and bushes; grass covered
14 opening in bamboo thicket; Altitude: 1500-
1520 m; Flowering time: August; Collection:
Section Ceratopetalae Kraenzl. C. Herrmann 28 & 52
17. Habenaria cornuta Lindl.
Platycoryne Rchb.f.
A rare species, recorded on only two sites
(Selga valley 2 km NE of Assosa, and near Ak 24. Platycoryne crocea (Rchb.f.) Rolfe subsp.
uda, 15 km NE of Assosa); Habitat: swampy montiseigon (Schltr.) Summerh.
meadows; Altitude: 1430-1500 m; Flowering
Found around Assosa and along the road be
time: August-September; Collection: C.
tween Bambesi-Begi, where it may form dense
Herrmann 39
stands; also recorded along the road between
18. Habenaria clavata (Lindl.) Rchb.f. Nedjo and Ghimbi; Habitat: meadows with
scattered trees and bushes, often on shallow
A rare species, found at three places in the
soils; Altitude: 1510-1600 m; Flowering time:
vicinity of Assosa; Habitat: Oxytenanthera
end of June-July (beginning of August); Collec
abyssinica thickets; Altitude: 1200-1520 m;
tion: C. Herrmann 5
Flowering time: August-September; Collec
tion: C. Herrmann 40
Disa Bergius
19. Habenaria holubii Rolfe
25. Disa aconitoides Sond. subsp. goetzeana
A rare species, found in only one area 3 km
(Kraenzl.) Linder
SW of Assosa; Habitat: meadows with scat
tered trees and bushes; Altitude: 1510-1575 m; Rare, found at only three very distant places: