It was on the Naturewatch website, and someone had posted a photo with a request for identification. I thought it looked like puha (Sonchus oleraceus), but then I changed my mind and identified it as Cape weed, Arctotheca calendula. The great thing about Naturewatch is that the identifications are crowd-sourced, and others quickly challenged my identification and convinced me, with evidence, that I was wrong. The plant was indeed puha (Sonchus oleraceus). (It's a bit embarrassing, because I wrote the Flora of New Zealand treatment for both these plants.)
So yesterday, I went looking for some fresh material. Here are the upper surfaces of the leaves:
|Cape weed (left) and puha, upper surfaces (scale=1cm)|
|Cape weed (left) and puha, lower surfaces (scale=1cm)|
Of course, it'd be hard to confuse them in flower, but early growth is often the time when foragers collect, because some plants get bitter when they run to flower.
|Cape weed (left) and puha in flower.|
The moral of the story is that identifying plants from photos can be difficult. Often the diagnostic characteristics can't be seen and sometimes the colours recorded in a photo don't look the same as in life. Plant taxonomists (specialists in the classification, naming, identification, and evolution of plants) often refuse to identify photos, but I believe that so long as people understand the pitfalls it's worth having a try. I really like the Naturewatch site, because it's self-correcting, democratic (everyone can have a go), and we all learn something from participating.