Thursday, 16 February 2012

Even scrubby riverbanks can be interesting.

Today we travelled from Picton to St Arnaud in Nelson Lakes National Park.  The road follows the Wairau Valley, which is formed along the Wairau Fault.  The Wairau Fault is a northern extension of the New Zealand Alpine Fault, a huge transcurrent fault that has separated rock formations on either side by 480 km in the few million years it's been active.

We had to stop at a swimming hole in the river at the Kowai Point Reserve, and it's just as well we did, because our trusty bus had developed a diesel leak.  So the students had a swim and I sat in the shade swatting blackflies.  Right there was a native Rubus in fruit:

Rubus is a genus of famous eating fruits: blackberries (serious weeds in New Zealand), boysenberries, cloudberries, and the like.  Sadly our native ones aren't so great.  These tasted like ordinary plant matter, neither fruity nor sweet, and there was almost no pulp around the seeds.  Maybe they trick birds into eating them, but then the birds fly off in fright, spitting out the seeds on the wing.  Or maybe not ...

After sitting under the shade of a kanuka (Kunzea ericoides) for an hour or so, I eventually noticed a small green mistletoe, Korthalsella, on a low branch, then another, and another.  In all there were 20 or so in a small area.  These have scale leaves and lack the spectacular red or orange flowers of some other native mistletoes like Peraxilla and Alepis.  Research by Dave Kelly and Jenny Ladley at University of Canterbury has shown those (see below) are pollinated by birds and small bees, which have to learn to twist the buds to pop them open.
Alepis flavida, taken on the 2009 Lewis & Clark trip, near Arthur's Pass.
The bus is now fixed and we're settled in to accommodation at St Arnaud; tomorrow we're climbing Mount Robert and the students will be devising and planning group research projects.

No comments:

Post a Comment