common_nature | Helminthotheca echioides

This is an invasive species in California and the rest of the US. Flora of Ireland describes it as, "an unattractive, bristly-leaved annual with yellow flower-heads." After spending time with it practicing botanical studio photography, i actually think it has some attractive aspects.

Phyllaries are the individual green, leaf-like structures at the base of the flower heads in the aster family. The collective structure is known as the involucre. Here, the involucre is made of two rings of phyllaries. The outer ones are loose and leaf-like, while the inner are upright and narrow, with thin membranes on the edges.

Here, two of the outer ring of the phyllaries have been removed, and white milky sap has collected at the wounds. The inner layer of phyllaries are much more erect and narrow, rather different in appearance from the outer phyllaries.

The five lobes that make up the "fringe" at the end of the petals indicate membership in the lettuce or chicory tribe (Lactuceae, Cichorieae). Jepson calls these ligules to distinguish between other asteraceae corola with three (occasionally two) lobes. The five lobes are remnants of the fusion of the five original petals of the ancestor asteraceae flower. Hard to distinguish here is that all the flowers in the head are the same. They open outer flowers first. This flower opened the day this was taken.