Poinsettia flowers part three: the female parts. Stigmas, styles, and ovaries ahoy!

A closeup of a poinsettia flower cluster from directly above it. Many people confuse the bracts (red leaves) with the petals of flowers; they're quite different.   This macro shot shows a number of bracts (colored leaves associated with a flower) surrounding the flowers (green, red, and yellow structures) and extending out of the frame.  The flowers themselves are called cyanthia; the green tissue surrounding each flower is an involucre, a cluster of bracts (leaves) fused into a cup-shaped structure that contains multiple male flowers and one female flower within it.  Emerging from the involucre you can see red filaments supporting yellow anthers on the male flowers; a single female flower should be emerging from the center of each flower.  The bright yellow, liquid-filled structures attached to the involucre are nectar glands filled with yummy sweet nectar to attract pollinators; on less-developed flowers they look like little light-green lips. (Marc C. Perkins)
A closeup of a poinsettia flower cluster from directly above.

[This is the third in a series of three posts. The first post is: Poinsettias up close: where are the flowers? and the second post is: Poinsettia flower closeups take two: getting even closer]

In my previous two posts on poinsettia (Euphorbia pulcherrima) flowers I showed that the flowers are much smaller than most folks think (the large red structures are bracts, not petals) and was able to get some closeups of the inflorescences illustrating their anatomy.

In case you’ve forgotten, the inflorescences of poinsettias are not your typical boring flower: multiple male flowers and a single female flower are surrounded by a sphere of fused bracts called an involucre, out of which the flowers emerge. The involucres often have nectar glands on them, which look like two green or yellow lips.

A closeup of a poinsettia flower cluster from the side.  Many people confuse the bracts (red leaves) with the actual flowers; they're quite different.   This macro shot shows multiple pseudanthia (flowering structures) surrounded by a sea of red bracts (colored leaves associated with a flower).  The flowers themselves are called cyanthia; the green tissue surrounding each flower is an involucre, a cluster of bracts (leaves) fused into a cup-shaped structure that contains multiple male flowers and one female flower within it.  Emerging from the involucre you can see red filaments supporting yellow anthers on the male flowers, and you can even see some of the pollen grains.  Also emerging from each involucre you can see a number of dark-purple structures supported by short stalks (that are about a tenth of the height of the filaments; I'm not sure what these are).   The bright yellow, liquid-filled structures attached to the involucre are nectar glands filled with nectar to attract pollinators. (Marc C. Perkins)
A closeup of a poinsettia flower cluster from the side. The involucre are the large green structures tipped with red, with male flowers emerging from them.

Frustratingly, when I took that first set of pictures I couldn’t find any female flowers on the plants I had. I’ve since learned that this is because the female flowers only develop and extend out of the involucre after the male flowers have matured and produced their pollen (reducing the likelihood of self pollination).  So, I waited, and yesterday finally got a chance to photograph the female flowers up close.

Here’s what a female flower looks like coming out of the involucre:

A single female poinsettia flower with stigma, style, and ovary can be seen emerging from its involucre (cluster of bracts fused together).  The involucre also has a nectar gland emerging from it (that look like two lips).  The entire inflorescence (involcure and female flower) is called a cyanthium.  The red leaves surrounding the inflorescences (mostly out of focus, except for the one next to the female flower) are bracts.  The scale bar is 5mm long. (Marc C. Perkins)
A single female poinsettia flower with stigma, style, and ovary can be seen emerging from its involucre. The scale bar is 5mm long.

There you can see the divided stigma (where pollen need to be deposited if they are to fertilize the flower’s eggs), the swollen ovary just barely protruding from the involucre, and the style connecting those two.

For more context, we can see that the maturing female flower is next to cyanthia filled with withered male flowers:

A single female poinsettia flower with stigma, style, and ovary can be seen emerging from its involucre (cluster of bracts fused together) on the right half of this image; the involucre also has a nectar gland emerging from it (that look like two yellow-green lips).  The entire inflorescence (involcure and female flower) is called a cyanthium.  On the left of the image a number of withered male flowers and their nectar glands can be seen emerging from shriveled involucres.  The red leaves surrounding the inflorescences (mostly out of focus) are bracts. (Marc C. Perkins)
A single female poinsettia flower with stigma, style, and ovary can be seen emerging from its involucre on the right half of this image; on the left a number of withered male flowers and their nectar glands can be seen emerging from shriveled involucres.

Those withered male flowers were actually quite delicate, and likely only remained on the plant because it was kept indoors and shielded from most disturbances.  I delicately put a ruler into the scene to get a scale bar after the shoot, and in doing so knocked off most of the male flowers.

In the image above the female flower is just poking out a little bit.  Looking around on the plant I found one that had extended far out of the involucre, supported by a large stalk (pedicel) that was longer than the stigma and style put together:

A single female poinsettia flower with stigma, style, and enlarged ovary can be seen emerging from its involucre (cluster of bracts fused together) on a thick pedicel (stalk) that's almost as long as the flower itself.  Also emerging from the involucre are a number of withered male flowers (stamen and anthers both visible) that still have yellow pollen on them.  The involucre has a nectar gland emerging from it (that look like two yellow lips).  The involucre also has small saucer shaped structures emerging from it; I'm not sure what they are (they're more easily visible in my other poinsettia pictures).  The entire inflorescence (involcure, male flowers, and female flower) is called a cyanthium.  The cyanthium is growing up from a stem's branching point, where a bract is emerging.  The red leaves surrounding the inflorescences (mostly out of focus) are bracts.  The scale bar (at the bottom) is 5mm long. (Marc C. Perkins)
A single female poinsettia flower emerging from its involucre (along with some withered male flowers) on a thick pedicel. The scale bar (at the bottom) is 5mm long.

And that, my kind readers, is what poinsettia flowers look like in a single image: one female flower and multiple male flowers emerging from an involucre that has a nectar gland on it and is surrounded by bright red bracts.

Thanks for reading!

More pictures

To see more of my poinsettia pictures, head to my Poinsettia Gallery.

8 thoughts on “Poinsettia flowers part three: the female parts. Stigmas, styles, and ovaries ahoy!

  1. Fantastic photos and extremely helpful descriptions. I am a Canadian on vacation in Kenya and got up close to a poinsettia tree this morning. Was fascinated and curious to see the colours and details of what I now know are the flowers in the centre of the bracts. Little black ants were crawling in and out of the nectar glands and a bee was collecting pollen from the male flowers. Back at my lodging, I got online and found your blog, which more than satisfied my curiosity. Thank you!

  2. This is great! I’ve never seen such close-up images like this before. The close-up of the flower cluster sparked my creative side and I started drawing it. I’ve been doing some research for drawing poinsettias and your pictures really help! Thanks!

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