34 
Cunninghamia 
Vol. 1 (1): 1981 
differing amounts or seasonal incidence of rainfall. Consequently, it is unlikely 
that all species will be found at a site at the one time. 
Naturalized species 
Of the 401 species recorded over the five sites, 55, or 13.75 %, were exotic species 
which have become naturalized in the area. These species represent 17 families and 
38 genera. The most prominent families were Poaceae (13 species), Asteraceae and 
Fabaceae (10 species each) and Brassicaceae (6 species). Two species from the 
family Verbenaceae were recorded, while the remaining twelve families contributed 
one species each. 
The list of naturalized species contains one shrub, Lycium ferocissimum, and 54 
grasses and forbs. Forty-one of these are annuals, 4 are annual to biennial, while 
the remaining 9 are perennials. 
The proportion of naturalized species varies from 10% at Trida to 20% at 
Micabil. The overall figure of 13.75% compares very closely with the 13.05% of 
introduced species recorded by Turner (1903, 1904) for the area of New South Wales 
west of the 147° meridian of longitude. On the other hand, Leigh and Mulham (1977) 
found that 29 % of the species on the Riverine Plain were naturalized. The network 
of rivers, creeks, swamps and irrigation channels across the Plain, together with 
more intense human settlement and land use, creates more favourable conditions 
for the spread and establishment of naturalized species. 
From these species collections it appears that naturalized species are now a part 
of the vegetation and will persist in the regeneration areas for a very long time, even 
in the absence of grazing. As they are mainly annuals, it is probable that many of 
the naturalized species were abundant before exclosurc but recent observations show 
that now they are often not abundant in the areas even after favourable climatic 
periods. On adjacent areas, which are still grazed by stock, naturalized species are 
often locally abundant, as is the case of Patersons Curse (Echium plantagineum) 
near Sayers Lake. This appears to be due to the fact that, in the absence of grazing, 
the total plant cover tends to be dominated by perennial forbs and grasses as was 
shown by Green, Walker & Cunningham (1976) at Cobar. 
Uncommon native species 
Several uncommon species have increased their numbers and maintained them¬ 
selves in the regeneration areas. Such species include Eleocharis obicis, which was 
thought to be very rare or extinct but which is locally abundant at Micabil, and 
Astrebla pectinata, which grows at the Booberoi Regeneration Area over a consider¬ 
able area (c. 0.5 ha). This species was first described from specimens collected in 
the locality by Mitchell in 1836, but is now not known to occur in the district other 
than in the regeneration area. 
t 
REFERENCES 
Beadle, N. C. W. (1948). The vegetation and pastures of Western New South Wales. 
Government Printer, Sydney. 
Green, D. R., Walker, P. J. & Cunningham, G. M. (1976). Rehabilitation of arid 
lands, 10 years of research at Cobar, New South Wales 1964-74. Soil Con¬ 
servation Service of N.S.W., Sydney. 
Leigh, J. H. & Mulham, W. E. (1977). v ascular plants of the Riverine Plain of 
New South Wales with notes on distribution and pastoral use. Telopea 1, 
225-293. 
Turner, F. (1903). Botany of the Darling, New South Wales. Proc. Linn. Soc. 
N.S.W. 28,406-442. 
Turner, F. (1904). Botany of South Western New South Wales. Proc. Linn. Soc. 
N.S.W. 29,132-181. 
