A chromosome number of n=8, 2n=16, has been reported by multiple publications.  Although a number of publications have reported experiments upon artificially produced autotetraploids in cultivation, it appears that wild populations are, so far as is known, exclusively diploid.

References

Balamani, G. V. A., and R. S. Rao. 1981. In Chromosome number reports LXXIII.  Taxon 30: 855-856.

Index to Plant Chromosome Numbers searchable database