Wild Parsnip uncomfortable companion to ivy

It looks like a carrot (plant). Or perhaps a giant parsley or celery. In any case, something you might drop into the carrot family, Apiaceae.

Instead, this native of woody heathlands on sand south of Melbourne - including Cranbourne where it appears in large numbers after fire and in the absence of wallaby and rabbit grazing (that is, within a protective fence) -  and further east and west of Victoria, as well as New South Wales and Tasmania, is now in the ivy family, Araliaceae. That family is also home to the Umbrella Tree (Schefflera).

The two families - Apiaceae and Araliaceae - are closely related in an evolutionary sense, as well as an orthographic sense ('ral' replacing 'p'), and together with a few others families form the 'order' Apiales.

This unusually large ephemeral, a species of Trachymene, is grouped together with the more subdued pennyworts (Hydrocotyle), another Southern Hemisphere genus well represented in Australia, a kind of back corner of the family Araliaceae called Hydrocotyloideae, a subfamily.

There are about 55 species of Trachymene, 46 of these occurring in Australia, 38 of them no where else on the planet. This one is from the latter category, and its called Trachymene composita. It's one of five species in Victoria and the largest, reaching up to 2.5 metres in flower. That's taller than you or me.

The specimens I photographed flowering in mid-November, in a grazing exclusion trial in Cranbourne Gardens (Royal Botanic Gardens Victoria) bushland, were up to about 1.5 metres tall. Shorter than me. Two month later the plants were fruiting, and shedding seed.

Trachymene composita is an annual or biennial (living two years), and a surprising member of this heathy community. Nearby there were Flying Duck Orchids (Caleana major) in flower, with their small stature and dark-coloured flowers, somehow more fitting of this ecosystem. The bold white flowers of the Wild Parsnip, with their soft pinkish hue, show there is more than one way to survive in this harsh habitat.  

Let's get back to the family placement, which intrigues me. As explained in VicFlora, both Trachymene and Hydrocotyle have been traditionally included with the carrots in Apiaceae, are very difficult to distinguish from the rest of that family which all have umbels (the umbrella-like arrangement of flowers you can see above). But then so do the Araliaceae.

Recent molecular data confirms these two genera are better placed with ivy in the Araliaceae, albeit in a separate 'branch' with Hydrocotyle. If desired, you could pull them out into a separate family I guess, but that doesn't help anyone.

We can but wonder and celebrate their affinities within the new family, noting with some unease perhaps that they look and taste more like their previous family: Trachymene composita has an edible (if fibrous) tuberous root, leading to the common name of Native Parsnip.

To finish a couple of their Flying Duck Orchid companions to feast on ...