So yesterday when I delivered some plants of the native species V. planopetiolata and V. colostylis to Massey University in Palmerston North, I took advantage of the trip to do some field work to try to get photographs for the new Flora. I targeted V. peregrina because it's only known at the one site. But first I went to look in a drain east of the Massey campus where V. anagallis-aquatica had been very common when recently collected. There was none there at all, and this demonstrates a common problem with weeds: their habitat changes all the time. Maybe the drain was drier this year, maybe the roadside had been sprayed with herbicides, or maybe other plants had crowded the Veronica out. There was a healthy population of Parentucellia viscosa, a non-parasitic member of the Orobanchaceae.
|Parentucellia viscosa flower, near Massey University, Palmerston North.|
|Linum trigynum, Kakariki.|
|Traveller's joy, Clematis vitalba.|
Two possible reasons for the absence of Veronica peregrina spring to mind. It could be that it's an ephemeral weed that comes up in the spring when these hollows are filled with water and dies off quickly as they dry out in early summer. Alternatively the plant might have flourished here briefly and then died out again, just like V. anagallis-aquatica at the Massey site. Its discoverer tells me he hasn't seen it in recent visits to the site, so the latter seems the more likely explanation, but I think I need to go back there next spring for another look (hopefully with a spot of lunch at Macfarlane's Cafe in nearby Feilding).
It seems odd that a new weed for the country could appear and flourish for a while in a tiny isolated patch alongside the railway and not be found anywhere else. So I thought it would be smart to look down by the Rangitikei River nearby, where damper soil patches might be found.
|Equisetum arvense between the bridges at Kakariki.|
|Equisetum arvense, Kakariki.|
|Veronica, Rangitikei river bed at Kakariki.|
|Mauve and pink flowered plants of Veronica anagallis-aquatica, Rangitikei River at Kakariki.|
It's going to be a challenge getting all 17–18 introduced species. Many are quite local, and likely not to be present at sites where they have been collected in the past. I've already done the three common local species: V. arvensis, V. persica, and V. serpyllifolia, and now I've added V. anagallis-aquatica. I'd be happy to hear of sites where the others can be collected, so I can add more posts to this series on the Great Veronica Hunt.