The New Zealand Plant Conservation Network

I found this plant in the shallows of lake Taupo in water about 30cms deep I've been growing it outside in ice cream container in the hopes it would flower giving me a clue to what it is but no such luck anyone have any ideas on what it is

Hi Benjamin, it looks like one of the Centipeda species. Unfortunately they don't flower when submerged! Grow it on damp gravel or potting mix. Some Centipeda species are quite rare so you may have found something special

I will try growing some of it in wet sand but I don't think it's a Centipeda I have Centipeda minima growing in a bucket and it doesn't look anything alike

Lobelia - most probably Lobelia angulata or the widespread hybrid between it and L. perpusilla - both occur on the lake shore and turf of Taupo and the adjacent Waikato River.They frequently hybridise and can grow happily submerged for many months in water up to 2 m deep.

yeah lobelia was my first thought but I grow both L.angulata and L.perpusilla submerged and it leaves are far smaller then ether I went through the lobelias and the only one it really looked like was L.fatiscens but that's only in the South Island so that can't be it

Thanks Peter, the zigzag stem would fit Lobelia. I haven't seen that hybrid combination, but I can imagine it would result in a leaf shape like in the photo

As I had mentioned - I believe your specimen is a Lobelia, and I then indicated two possibilities within than genus. Lobelia angulata is a species complex - we have a number of entities within it, so it's not easily dismissed because your comment about L. angulata would depend on which entity you have growing. The other possibility I raised was you have the hybrid between that species aggregate and L. perpusilla. This hybrid is very common around Lake Taupo and along the Waikato River to about Port Waikato - and it too is very variable with respect to leaf size, width, areolation etc - some hybrids flower others don't.

My suggestion is grow it on and wait for flowers

Thanks for the help identifying that one any idea on this other on growing in one of my buckets

That's a mix of species - the most common in your image is a species of Galium - probably G. palustre but there is also a Callitriche in your image and possibly Elatine