"I heard a great kerfuffle going on behind me and looked and saw these two kangaroos boxing themselves silly!"

A photographer (you can see more of his pictures on Twitter via @tomowensmith), he was equipped with a camera and was able to capture some of the scuffle.

He wonders if they were coming to blows over the hot topic of Parliament's attempts to repeal the carbon tax, a subject that has upset all thinking Canberrans.

For some of us who have a smattering of botany, the debate about which tree species should furnish the Northbourne Avenue light rail route is causing some exasperation.

So, for example, a (misguidedly) confident letter to the editor asks for some beautiful and bold jacarandas and flame trees to go into the Northbourne mix. Yes, and a recreation of the lush jungles of the Amazon (the vines! the toucans!) would also be a visual treat for commuters.

But, of course, there would already be jacarandas and flame trees everywhere in Canberra if not for the fact that, native to balmier climes, planted here they either freeze to death or live lives of stunted misery.

In his authoritative Trees In Canberra (1962) Professor L. D. Pryor advises: "It may be somewhat astonishing [to visitors] ... to find that some well-known plants, which are widely used in other parts of Australia, missing from the Canberra scene.

"Among the most outstanding of these is Jacaranda mimosifolia, for which Grafton is well known. This will not grow in Canberra because it is first damaged and then killed by winter frosts. The same is true of ... the Illawarra Flame Tree (Brachychiton acerifolium)."

With our smattering of elementary botany we toss into the discussion the Northbourne possibility of the silky oak (Grevillea robusta). An Australian tree, it would be a botanically patriotic choice. Pryor was already enthusiastic about it in 1962 and pointing to successful plantings along Baudin Street in Forrest (still doing well today).

Today there is a terrific cluster of them at Canberra Avenue at Manuka (opposite Manuka Oval). There are buoyant individuals in the suburbs and my own neighbourhood of (Upper) Garran is blessed with some rippers.

The massive flowers (in fact, clusters of smaller flowers) are a spectacular, golden tangerine colour and the bipinnatifid (Pryor's posh word) leaves are fern-like and lovely. It may be that, doing well already in frosty Canberra but native to northern New South Wales, global warming may make it even more radiantly cheerful here.

God was at the peak of his form when he created G. robusta and, given that we know he approves of light rail, we feel sure he wants to see the trains gliding silkily along an avenue lined with his silky oaks.

Erindale College is reported to be agonising over what to do with its 13-metre long mural, painted by Rolf Harris, now that the wobble board virtuoso has been convicted. Local authorities in a Melbourne suburb are about to paint over a Harris mural the wobble boarder daubed on a wall.

But, if a creative artist is shown to have been a sinner, is his or her art necessarily wicked too? Will it corrupt those who see, read or listen to it? If so, what, for example, are many noble Australian institutions to do with their works by paedophile Donald Friend? Are they never going to exhibit them again?

And what are the world's great galleries to do with their Caravaggios given that the artist (circa 1571-1610) painted angelically but was a brawling hooligan who killed a youngster in a fight and fled?

And what of the way the world's musicians and ABC Classic FM continue to perform/broadcast the music of Carlo Gesualdo (1560-1613), famous for the murder and mutilation of his wife and her lover?

Might the world be a drearier, less stimulating place without the works of art of the world's gifted swine? Are the pure, with nothing in their consciences to torture them and educate them to life's horrors, even capable of very fine art? Is this why the "music" of Hildegard of Bingen, a saintly nun, is just a series of tuneless souffles?

Where would you stand, dear reader, if a wall in your suburb bore a hitherto popular mural by someone (Caravaggio, say, or Harris) shown to have a vile side? To obliterate or not to obliterate?