The Aster Family (part 4)

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Tragopogon (goatsbeard) species (I think)

 

 

Each floret of a composite family plant produces a single fruit (which contains a single seed) called a cypsela. In many texts and on-line sources, the term achene is used. The difference between the two is technical (it depends on the position of the ovary), and for years both were used rather loosely. While trying to make sense of this I tripped over an article in the Brazilian Journal of Botany, the poorly translated abstract for which reads

The worry about the indiscriminate use of the terms cypsela and achene for the fruits of Asteraceae has been frequently detached by specialists in this family. The present work was developed aiming to verify the existence of arguments to justify the adoption of a term against the other. After historical and anatomical analysis, we concluded that there is technical basis to consider cypsela and achene as different types of fruits. For Asteraceae, the correct is to call cypsela; achenes are only derived from superior ovaries, as in Plumbaginaceae.

At any rate, picture a single small seed with a tuft of hairs, like dandelions have.

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Erechtites hieracifolius (pilewort)

 

 

That’s pretty much it, unless there are barbs instead of hairs:

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Bidens bipinnata (Spanish needles); note the capitulum (flower head) with yellow ray and disk florets at top, another flower head showing the phyllaries in the middle, and the barbed cypsela at the lower right

 

 

next: lower classifications

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