Nodding chocolate lilies, an Australian native plant, are in flower and they smell a lot like the real thing.

Tim Yiu, a biodiversity officer at ANUgreen, the university's environmental management program, said the flowers began blooming last week in the Old Canberra House grassy woodlands, a nationally critically endangered ecological community on the university's grounds.

The flowers will only last another week or two, he said. ''I've been been able to smell them on the wind when it was a very windy day, but then you get down close and then you smell chocolate, it's more the smell of cocoa,'' he said.

A senior lecturer in biodiversity at the Fenner school of environment and society at the ANU, Jamie Pittock, said nodding chocolate lilies were relatively widespread but in low numbers, because they were very susceptible to being eaten by grazing animals.

Dr Pittock said the university was the best place in the ACT to see the flowers in the wild.

''Anywhere where you've got too many cattle or sheep, too many kangaroos or too many rabbits for example, the chocolate lilies get knocked out,'' he said.

''One of the reasons why this site on Acton Peninsula is so important is that a whole lot of wild flower species like these chocolate lilies survive in really good numbers.''

Dr Pittock said most of the grasslands in central Canberra tended to have one kind of dominant grass and a few different types of flowers, but the university site was unusually diverse and of tremendous value in terms of conservation.

Now was also a good time to spot hoary sunray, a nationally endangered member of the daisy family, at the site.

But for those who cannot make it to the campus before the chocolate lily flowers disappear, Mr Yiu said vanilla lilies, which are also named for their smell, were expected to appear a few weeks later.