Distribution and cytology of Australian Neurachne and its allies (Poaceae), a group containing C3, C4 and C3-C4 Intermediate species
HDV Prendergast and PW Hattersley
Australian Journal of Botany
33(3) 317 - 336
Cytological, phytogeographical and habitat data are presented for the Neurachneae (Poaceae), a tribe endemic to Australia and containing seven C3 two C4 and one C3-C4 intermediate species. Chromosome counts for 34 accessions Australia-wide reveal a typical eu-panicoid base number (x = 9). Three species are diploid (Neurachne tenuifolia C3, Thyridolepis mitchelliana C3 and T. xerophila C3,); four species (Paraneurachne muelleri C4, N. minor C3-C4, N. lanigera C3, T. multiculmis C3) are tetraploid only, one (N. queenslandica C3) is hexaploid only, while two (N. alopecuroidea C3 and N. munroi C4) are variable. Aneuploidy was found in individuals of N. minor (2n = 4x+1) and N. queenslandica (2n = 6x -1). Chromosomes are small (mean c. 2 µm) and metacentric or submetacentric. Using localities derived from all known collections in Australian herbaria, actual and computer-predicted distributions were mapped using the Bioclimate Prediction System (BIOCLIM) developed by H. A. Nix and J. R. Busby. Species distributions, habitats and chromosome counts are discussed in relation to photosynthetic pathway, present and past climates and evolutionary history. The Neurachneae are mainly subtropical, arid and semiarid zone plants. However, the distribution of their C3 species contrasts with those of other C3 eu-panicoids and C3 grasses as a whole. The temperate species N. alopecuroidea is the only native C3 eu-panicoid known from south-western Australia. It is suggested that phenotypic expression of C4, photosynthesis in the Neurachneae occurred independently of other grasses and that they did not extend into arid and semiarid regions from a mesic temperate zone.
Full text doi:10.1071/BT9850317
© CSIRO 1985