What goes on inside those rosy bracts?

Take a look at this fantastic (i.e. fanciful, remote from reality) bunch of flowers seen on the streets of Marrickville back in May. They adorn a small untidy shrub, emerging from a square cut in the asphalt path. 

Check out the yellow, mick-jagger-like, lips and rosy-red burlesque headdress. Each apparent flower has bold yellow, red and green markings, all clustered within those familiar red leafy bracts.

Yep, it's a Poinsettia, normally spotted in nurseries around Christmas time after being forced to flower in the Australian summer (if you want read more about when and why they flower, see my two previous posts on this topic (2011 and 2014).

The Poinsettia photographed here is responding to the late autumn climate of Sydney and putting on a stunning floral display ready for winter. But what is really going on with all those bumps and garnishes within the big red welcoming flags?

Let me switch to botanical jargon. The red-tipped, swollen green pots and their embellishments are called cyathia. Each cyathium includes one very reduced female flower and a few male flowers. 

There are no petals and the yellow lips are glands that secrete nectar - which is why an ant has it's bum sticking out of one above. 

I described another kind of cyathium a few years ago, in another member of this genus called Medusa's Head. In Poinsettia, we have one female flower on top of the green pot displaying three feathered extensions that split further to create six separate tips. Remember, not petals or any other additional parts. 

(Note another insect enjoying the nectar from Mick Jagger's yellow lips)

The male flowers consist of a single stamen topped by two anthers. You can see them in various states of maturity in a ring around the female flower. There are probably six in each cyanthium.

In some of the cyanthia below you'll see ovaries (in the female flowers) post-fertilisation, swelling above the cyathium, and adding another unusual edifice to those bizarre flower structures. They all nestle, as I said, within the red bracts that look like leaves.

OK, enough of the close-ups. It's so hard to stop...

While this species is native to Mexico, there are a few Australian species of Euphorbia that resemble Poinsettia in leaf shape and flower arrangement, particularly in the north. But if you see a plant like this in a pot all dressed up for Christmas, or a 'leggy shrub' in a garden, or less commonly, a scraggy street tree such as I've photographed here, it's most likely Euphorbia pulcherrima.  

Let me finish with a few plain old leaves.