Tussilago farfara (NL: Klein hoefblad / EN: Coltsfoot / DE: Huflattich / FR: Tussilage, Pas-d'âne).
Description of the species: see previous post.
In this image the center of the inflorescence is displayed. You can see here in detail the most evident characteristic of Asteraceae: a specialised capitulum, technically called a calathid or calathidium, but generally referred to as flower head. This flower head is a contracted raceme composed of numerous individual sessile flowers, called the florets, all sharing the same receptacle. It looks like a single flower, but it isn't !
The florets have five petals fused at the base to form a corolla tube and they may be either actinomorphic (a "star shaped" or "radial" symmetry) or zygomorphic (a "yoke shaped" or "bilateral" symmetry).
There are generally two types of florets in Asteraceae and both types are present in this species (and in the image): the "Disc florets" and the "Ray florets".
* Disc florets are usually actinomorphic, with five petal lips on the rim of the corolla tube. In the image the Disc florets are the inner type of flowers - most of them still closed (yellow buttons) but the outer circle open yet. The anthers covered with pollen are popping out of the centre of these flowers.
* Ray florets are always highly zygomorphic and are characterised by the presence of a ligule, a strap-shaped structure on the edge of the corolla tube consisting of fused petals. In the image the Ray florets are the little yellow ribbons at the outside of the flower. The little styles (with stigma) of these florwer can be seen just beneath the Disc florets.
Next time you see a member of the Asteraceae family (like aster, daisy, or sunflower) maybe it is worthy to have a closer look, trying to discover these different types of florets ...
Image: Ranst (B) - 22/02/2012
© Johan Dierckx
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