Saturday, 5 June 2010

It's a Seed, But Not As We Know It, Jim


Actually Jim, it's an anthocarp, a mauka anthocarp. On one of my mauka roja plants. I'll put the tricorder down for a minute and explain. An anthocarp is a specialised fruit found in the family Nyctaginaceae to which mauka (Mirabilis expansa) belongs. And before you ask, yes, I do know what a nail brush is.

Seems like my clumsy fumblings have resulted in a single, successful pollination. Alternatively, it may have happened spontaneously, without any connection to the prodding and poking which I doled out to all the hapless flowers I encountered.

What looked like pink petals in my previous picture weren't - they were colourful sepals standing in for the petals, which went AWOL sometime in the evolutionary history of this family. Similarly, what looks like a ripening seed is, from the botanist/pedant's viewpoint, a fruit, albeit somewhat unlike the common conception of one. It's an achene (dry fruit) wrapped in a persistent calyx - known in botanical shorthand as an anthocarp. In mauka's case this outer wrapping is covered in sticky hairs. These must help the ripe seeds stick to any passing birds or animals which then distribute them to new areas.


Here's a close-up of the achene, divested of its glandular, sticky coat. There are definite ridges present on its surface - a common feature in Mirabilis species.


So, although I don't know whether this mauka propagule is viable, it seems likely that, under some circumstances at least, mauka can self pollinate. This can only be a good thing.

4 comments:

Rebsie Fairholm said...

Happy times! Maybe you pollinated it with your shirt sleeve after all.

I'm glad about the fingernails. I have a similar picture of mine which I've been afraid to post because my mum will tell me off if she sees it. You've made me feel better about it now.

Vegetable Heaven said...

Nail brushes are for when you're going to cook the tea!
My mum doesn't 'do' technology, Rebsie, so I can get away with it.

Congratulations on your little one. Look forward to reading about its future progress.

orrflo said...

Owen,
that's great!! Now we have to found out how they could produce an abundance of flowers, and after that we can start crossing things. I wonder if the 'wild' mauka is able to produce more flowers. This is after all one of those Andean tubers/roots that probably has been selected for vegetative reproduction, and could have lost some of the capability to form flowers.

Rhizowen said...

Rebsie - I do tend to leave my cuffs undone, so that large swathes of material brush across everything - maybe that's what happened.

Veg Heaven - I'll let you all know how the little'un does

Orrflo - I suspect that artificially shortening the day length combined with bright summer light might encourage more flowers to develop.

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