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Flora
The flora
of Oman comprises about 1204 species of vascular plants. Of
these 1182 species are angiosperms (flowering plants) comprising
568 genera in 119 families, 3 species of gymnosperms (non-flowering
plants) and 22 species of vascular cryptogams (seedless plants).
There are 39 families represented by one species, 372 monospecific
genera, two genera with more than 20 species and 14 genera
with 10 or more than 10 species. The southern and northern
mountains of Oman are the most species-rich areas with 72%
and 60% of the total species respectively. One of the most
significant features of the flora of Oman is its relationship
with the North African, Iranian and Baluchistanian floras
indicating biogeographical links with these regions.
There
are 138 taxa, which constitute the critical flora of Oman.
Of these 56 species are endemic and 39 are regionally endemic.
There are 64 species whose Arabian distribution lies only
in Oman; some of these are included in the IUCN Red Data List.
Using the evaluation of the status of species as outlined
in the IUCN Red List Categories, 1 species is evaluated as
Extinct in Oman; 9 species are placed in the Critically Endangered
category for Oman, 2 of these both endemic to Dhofar, are
also placed in the IUCN Red Data List; 2 species are placed
in the Endangered category for Oman; 20 species are placed
in the Vulnerable category; of these 13 are included on the
IUCN Red Data List and 14 on the Oman List; 29 species are
placed in the Low Risk category; of these 11 have been placed
on the IUCN Red Data List and 21 on the Oman List; 27 species
lack full data on their distribution and population status
and are therefore placed in the Data Deficient category, 11
of these are on the IUCN Red Data List. A Plant Technical
Working Group is being set up to bring together the available
technical expertise, to consider all aspects of plant data
collection, evaluation and the monitoring of the critical
flora and habitats. The Plant Technical Working group will
help to draw a national action plan for the conservation of
plants in Oman. A proposal to set up a National Committee
for Biodiversity to address issues on biodiversity is also
under consideration.
The
critical flora
One hundred
and thirty eight taxa have been identified which constitute
the critical flora of Oman . There are 64 taxa which are distributed
elsewhere in the world, but whose distribution in Arabia lies
only in Oman , some of these are on the IUCN Red Data List.
Many of these species may not be under any threat or risk
of extinction, nevertheless it is important to document and
monitor them as they represent the biological diversity of
the flora of the Arabian Peninsula and are an insight to the
understanding of the biogeography of Oman.
Collection
data on several species of grasses in Oman is incomplete since
many people do not like to collect grasses as they 'all look
the same'. Several species of grasses are relatively short-lived,
come up soon after the rains and are easily missed out by
collectors. There are many species with single or at most
a few collections whose status cannot be determined as guesses
could be totally misleading. These are not included in this
list. However a sharp decline in the populations of most of
the grass species (apart from the weedy and unpalatable species)
in the hills of Dhofar has been noticed in the last 5 to 6
years (1989-1995). It is envisaged that unless grazing is
controlled, there will be no tall grassland left in the monsoon
affected areas. At present the dominant tall grasses appear
to be common, but only where the grassland is relatively ungrazed.
Taxa are
described as a species, subspecies or a variety. There are
56 endemic taxa, excluding the new undescribed species and
39 species, which are regionally endemic. Regionally endemic
species are those which are endemic to a particular region.
They have their centre of distribution
in Oman but their distribution extends beyond the political
boundaries of this country. Most of the regional endemics
are distributed in Dhofar and South Yemen and a few in the
mountains of
northern Oman and the UAE. In Oman, three local centres of
endemics are identified, each with
a concentration of endemic taxa These are:
- The
escarpment woodlands of Dhofar where about 63 taxa are endemic
or regionally endemic. Two regionally endemic genera, Cibirhiza
and Dhofaria are also recorded from there; the
- limestone
plateau of central Oman, where 12 species are endemic. Amongst
these Ochradenus harsusiticus and Hyochyamus gallagheri
are common and the
- mountains
of northern Oman (including the Musandam Mountains), where
about 17 taxa are endemic.
One species
is identified as extinct in Oman. This species, Delphinium
penicillatum (Family Ranunculaceae), is known from southern
Iran and northern Oman. It was collected by Aucher-Eloy, a
French plant collector, in 1838 from Nizwa (northern Oman)
and despite several attempts to locate it, has not been collected
since. Aucher-Eloy's collection from Oman is the holotype,
which means that the species was originally described from
this specimen. The holotype and the isotype are present at
the Natural History Museum in Paris, France. Delphinium penicillatum
is distributed in Iran and cannot therefore be included in
the IUCN Red Data world list but is placed in the Extinct
category for Oman. Nine species are placed in the Critically
Endangered category, 2 of these, Aloe whitcombii (family Aloaceae)
and Rhytidocaulon fulleri (family Asclepiadaceae) both endemic
to Dhofar, are also placed in the IUCN Red Data List. Two
species are placed in the Endangered category in the Oman
List. A total of 20 species are placed in the Vulnerable category;
of these, 13 are included on the IUCN Red Data List and 15
on the Oman List. There are 29 species in the Low Risk category;
of these 11 have been placed on the IUCN Red Data List and
21 on the Oman List. 27 species lack full data on their distribution
and population status and are therefore placed in the Data
Deficient category, 11 of these are on the IUCN Red Data List.
Eight species are as yet not evaluated against any criteria,
one on which is on the IUCN Red Data List.
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