plants use sunlight and carbon dioxide to make sugars warm-season grasses. they brown off in winter in southern which fuel their growth; this is photosynthesis. sunlight is
australia. and C3 grasses, also known as cool-season
harnessed for energy by the same process in all plants, but
grasses, have their period of active growth in autumn and
carbon dioxide can be taken up by different means in spring. While many brown off over summer, they remain different groups of plants.1 two pathways, the C3 and C4
pathways for the uptake of carbon dioxide, have evolved in
at the time of european arrival, native grasslands were a
the grasses. not only do these differ in the chemical
mix of mainly perennial, warm- and cool-season grasses.
reactions that incorporate carbon dioxide into organic
in south australia, the drought tolerant and often tall-
molecules and in the structures in which photosynthesis
growing warm-season grasses were dominant over the
occurs, they lead to marked differences in the distribution
smaller cool-season grasses. While stock flourished on the
and growth patterns of C3 and C4 grasses.2
diversity of year-round feed, the C4 summer-green species
Only 1% of plants use the C4 pathway and more than 60%
in particular were soon eaten out and to this day remain
of these are grasses. among the australian grasses, some
largely absent in the landscape.3 these mostly perennial
65% of native species are C4. they are most numerous in
warm-season grasses have a far wider adaptive range and
the northern territory, northern Queensland and the
respond more rapidly to summer rain than the frequently
Autumn WINTER Spring
Spring SUMMER Autumn
Kimberley, where they can make up more than 90% of the
annual cool-season grasses that replaced them. as a group,
grass species. On the other hand, C3 grasses are most
the C4 grasses not only can have value in extending the
numerous in the south-eastern and south-western corners
availability of useful forage, but their active summer growth
of australia. these distribution patterns relate particularly
(when the annual cool-season grasses are dead) reduces
to temperature and rainfall. in general, C4 species are more
deep drainage to water tables, a factor contributing to
common in areas with a warmer, wetter, growing season
dryland salinity, and protects against erosion.4
and often with a drier cold season than are C3 grasses. Just as C3 and C4 grasses are actively growing at different
Conversely, fewer C3 species are found in areas with high
seasons, their seed germinates most reliably over different
January average maximum temperature and more in areas
temperature ranges. C3 grasses germinate best over a
temperature range of 15–25 ºC while C4 grasses germinate
the biochemical and structural differences between the C3
best over the range 25–35 ºC. Choice of sowing time largely
and C4 pathways mean that the optimum temperature for
depends on the rainfall distribution at the site and the
photosynthesis is higher in C4 than in C3 plants. as a
species to be sown. in south australia, C3 grass seed should
result, C4 grasses tend to have their period of active growth
be sown in autumn and C4 grass seed from spring to early
in summer and so are also known as summer-active or
summer to catch the growing conditions that suit each best.
Autumn WINTER Spring
utumn WI R ER Spring
Spring SUMMER Autumn C H or activ
the genera listed here particularly refer to South Australia.5 a bracketed Latin name identifies the one
the generally accepted name for that genus. the various species can be found in grasses of south australia.6
Per GENERA
season grasses MON NAME
ennial nativ N
Per N NAME Cynodon (dactylon var. pulchellus) Couch-grass
Umbrella-grass & Curly windmill-grass
Monachather (paradoxus) Bandicoot grass
Pentapogon (quadrifidus) Five-awned spear-grass
* Neurachne has two C3 and one C4 species in south australia. SetariaReferences: 1. J.r. anderson & J. Beardall Molecular Activities of Plant Cells: An introduction to
5. W.r. Barker, r.M. Barker, J.p. Jessop & H.p. vonow (eds) Census of plant biochemistry. Blackwell scientific publications, Oxford & Melbourne, 1991. South Australian Vascular Plants, 5th Edition, Botanic gardens of adelaide
2. r. sinclair, ‘ecophysiology of grasses’ in Flora of Australia, Vol 43, Poaceae 1, Introduction and Atlas, australian Biological resources study/CsirO, Canberra,
6. J. Jessop, g.r.M. dashorst & F.M. James, Grasses of South Australia: An illustrated guide to the native and naturalised species, Wakefield press,
3. J. reseigh, p. Foster & r.J. Myers, Native Grass Strategy for South Australia 2: Management of native grasses and grassy ecosystems for sustainable production
7. the Council of Heads of australasian Herbaria in 2011 accepted the
and biodiversity conservation. rural solutions sa, adelaide, 2009.
2010 reclassification of Austrodanthonia, Joycea and Notodanthonia
4. B. Johnston, d. garden, s. ellis and C. Clifton, Hill Country Native Grasslands:
to Rytidosperma by an international team of botanists (H.p. Linder et al.
Better management for healthy catchments. Murray-darling Basin Commission,
Annals of the Missouri Botanical Garden, 97(3), 2010, pp. 306-364.)
_________________________________________________________________________________________________ Reasons for Slow Development of Antimycotic Therapeutic Agents Systemic fungal infections until recently have been considered rare. Economics of drug companies traditionally have been such that the cost of development and testing did not seem to warrant extensive efforts (dramatic change