Black flowers provide bed and breakfast

As I said back in 2010, there are now black tulips, black roses, black violets, black hyacinths and, freshly created at that time, black petunias. Funnily enough, though, none of them are black. They are at best a rather darkish purple.

These were all bred artificially (that is, by us, the humans), seeking a flower that according to the hype at the time, would be intriguing, sexy and...something different.

I left out of that list some naturally occurring blackish flowers. The one you are mostly likely to encounter in Melbourne, although possibly not notice, is that of the New Zealand hedge plant Pittosporum tenuifolium. This is a commonly planted species, often in its variegated form (with white, silver or purple markings).

Although often sold as a cultivar called 'Nigricans', which means black, that name refers to the stems rather than the dark red or purple (blackish) flowers. In New Zealand this species is sometimes called the Black Matipo*, which I like the sound of. Matipo is a name given to a range of different shrubs by the Maori and in this case it seems to refer to the wavy edges of the leaves.

The flower of the Black Matipo varies from purple through to what to all intents and purposes looked black or at least very deep red when I photographed this hedge in Hawthorn back in September.

A small blackish flower that is difficult for animals such as ourselves to see is an interesting evolutionary adaptation. Birds eat the fruits but, not surprisingly given their size, don't visit the flowers. Insects are usually implicated in pollination.

The flowers produce a honey-like perfume at night, which would normally be associated with a light coloured flower to attract moths. A prime example is our own Pittosporum undulatum, with its rich evening scent and very white flowers. Maybe the insects just stumble into the Black Matipo flowers, attracted solely by the heady perfume.

The best rationale I can find for dark coloured flowers is to provide a safe resting place, what is termed a 'protective shelter'. This argument has been used for the dark red or purple colour of some iris flowers.

Male solitary bees, in particular, are on the look out for places to rest overnight. So at the end of the day, when the Black Matipo flower is emitting its perfume, some insects will be out searching for a suitable rock or tree hollows where they can overnight. Popping out the next morning they will presumably carry pollen off to the next day's resting place, possibly another Black Matipo.

The male eucerine bees in the iris study don't visit the flowers at all during the day or at least when the sun is out. So our Black Matipo might be saving its attractive perfume for the evening as a extra enticement for bees to spend the night in their flower.

Unlike the iris, though, I'm presuming Black Matipo does provide a nectar reward as well. Pittosporum undulatum  is rich source of nectar for various insects and birds and I think most species of Pittosporum produce something sugary in the their flowers.

None of this I can prove having only seen the flowers in the middle of a sunny day. Do have look next time you see this hedge in flower. Perhaps pull up a chair and a beer in the evening, and see who arrives for the night.

The Black Matiop is is a tough old plant, which is why you see it, if not its flowers, a lot. It's also naturalised (that is, become self sustaining in our natural bushland) so outside gardens you see it more often than you should.

*Postscript: Stuart Read tells me the name Matipo is more commonly applied to Myrsine australis (also called the Mapau), which doesn't have black flowers. I guess this is why the adjective 'black' is added to it when used (albeit uncommonly) for Pittosporum tenuifolium. Stuart says Kohuhu is the more commonly used common name for our Pittosporum. Other New Zealand species of Pittosporum, again thanks Stuart, can have dark-red or blackish flowers or sometimes simply red.