Puha

Before European contact brought a wealth of Eurasian and American temperate crops to New Zealand, Maori had to find their food among the native flora and fauna and the few crop plants they brought with them from the tropical Pacific.  New Zealand lowland plants are often woody and there are not many suitable green vegetables.  One of the best is puha, sometimes spelled puwha.

Puha seedling

Puha is classified in the genus Sonchus, which is part of the daisy family Asteraceae.  Within Asteraceae, puha belongs in the tribe Lactuceae, along with lettuce, dandelion, chicory, and salsify.  The name Lactuceae refers to the milky juice that's characteristic of this tribe.  This juice contains sesquiterpene lactones, whose bitter tastes probably protect the plants against grazing.  These have been reduced in commercial lettuce varieties by plant breeding.
Native species.

New Zealand has between three and five native species of Sonchus, plus three introduced ones.  Few New Zealand botanists would agree with me about the number of native species; most would say there's only one.  In fact, I'm the author of the most recent Flora treatment of Sonchus (in Webb et al., 1988) that says there's only one, so I'll explain the reasoning behind my change of heart. 

First, there's Sonchus kirkii, which was probably the original Maori puha.  It's a coastal plant with rather thick and glaucous (bluish-green) leaves.  The New Zealand Plant Conservation Network notes that it appears to be declining in abundance.

Sonchus grandifolius, cultivated at Otari–Wilton's Bush

Secondly, there's S. grandifolius, confined to the Chatham Islands.  It was separated from Sonchus by Egyptian botanist Loutfy Boulos in 1965 and placed in a new genus, Embergeria.  It differs from most Sonchus in being much larger in all its parts and lacking barbs on the pappus hairs at the tips of its fruits.  This is another of those cases of classifying plants separately if they're different from their close relatives.  However, large size and loss of adaptations for dispersal are common features of island plants worldwide, and I expressed doubt about this classification back in 1988.  Since then, molecular systematics (Kim et al. 2007) has shown S. grandifolius clearly is a member of the Sonchus lineage; to treat it as a separate genus would disguise its true relationships.

Finally, another 1–3 species should be added to New Zealand Sonchus.  The endemic genus Kirkianella was described in 1961 because the plant previously known as Crepis novae-zelandiae clearly didn't belong in Crepis.  In the 1980s I formed the view that it might rather belong in Sonchus.  I wish I'd said so at the time, because recent molecular systematics research has borne this out (Kim et al., 2007).  Its DNA sequences and its fluffy pappus are evidence of a close relationship to S. grandifolius.  It looks as if the great British botanists Bentham & Hooker came to the same conclusion; the International Plant Names Index lists Sonchus novae-zelandiae attributed to them, but I haven't checked it in the original yet to see if they formalised the name.  At the moment there's only a single species recognised in Kirkianella, but there are two different chromosome numbers and a range of leaf shapes, which are strong clues that there could be more than one species involved.

Introduced species.
Of the three introduced species, S. arvensis is a large creeping perennial with large flower heads and conspicuous yellow glandular hairs on the outer bracts.  It's known from a few locations in Hawke's Bay, Canterbury, and Otago. 

The two common wild species are S. asper and S. oleraceus.  S. asper is an annual or biennial with softly prickle-edged leaves and smooth fruits, whereas S. oleraceus is an annual with toothed leaves and wrinkly fruits.  

Puha, Sonchus oleraceus

 The name S. oleraceus gives it away as a plant that's good to eat, and this species has largely superseded S. kirkii as the edible puha.  Moreover, Kevin Gould and colleagues found it had antioxidant levels several times higher than blueberries (Gould et al. 2006).  But S. kirkii is said to be easy to grow from seed, so it'd be an interesting addition to the vege garden, and growing it could help conserve the species (but don't collect plants or seed from the wild; try a good native plant nursery).

So what's puha like to eat?  I have to admit I haven't tried it, and I'll instead refer you to Johanna Knox's blog "Wild Picnic" and her tempting recipe for puha pakoras at "Wild Concoctions".  Incidentally, the latter recipe featured recently on TV2's Erin Simpson Show, unfortunately without attribution, although it appears to be no longer on the show's website.  That's a serious breach of netiquette, or worse. 

Added7 July: I'm told TV2 have now apologised profusely to Johanna and other recipe bloggers and removed all recipes from their website.

References.

Gould, K.S.; Thodey, K.; Philpott, M.; Ferguson, L.R. 2006.  Antioxidant activities of extracts from traditional Maori food plants.  New Zealand Journal of Botany 44: 1—4.
Kim S.C.; Chunghee L.; Mejías J.A. 2007. Phylogenetic analysis of chloroplast DNA matK gene and ITS of nrDNA sequences reveals polyphyly of the genus Sonchus and new relationships among the subtribe Sonchinae (Asteraceae: Cichorieae). Molecular Phylogenetics and Evolution 44: 578–597.

Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. 1988.  Flora of New Zealand Vol. 4.  DSIR, Christchurch.