Tuesday, 29 January 2013

Wednesday wildflower: Impatiens glandulifera

Impatiens glandulifera.
Impatiens glandulifera is occasionally naturalised in New Zealand; this one is in Norway Street, Aro Valley, Wellington.
Impatiens glandulifera flower.
It's known in England as policeman's helmet, for the shape of the flower.  It's a large flower with a wide opening that fits the body of a bumble bee very nicely.  The flower is protandrous—male parts mature before female parts—and after the pollen has gone, the insect visitor knocks the stamens off, revealing the stigma for the next visitor to contact.

It's interesting to speculate whether specialised bee flowers such as this would have survived in New Zealand without their pollinators.  Probably something else would have done the job, but maybe not so efficiently.  New Zealand native bees are solitary (they aren't social bees) and they have short tongues so they can't probe deep into flowers.  They're important pollinators of many native flowers, especially the genus Veronica (e.g., hebes and their relatives).

Nowadays we lament the loss of honey bees due to varroa mite and pesticides, and worry about the effect on crop and fruit tree pollination.  But if these bees weren't here, maybe some weeds wouldn't do so well.

Impatiens fruits are fun.  They burst explosively when touched, scattering the seeds far and wide. I'm planning a series of posts on flowers and fruits that move, and this will definitely be one to include.

Sunday, 27 January 2013

Ruppia fruits

Ruppia is a small genus of aquatic monocotyledons in their own family, Ruppiaceae.  Vegetatively they're nothing unusual, with slender leaves like so many others.  Their flowers are clustered and hermaphrodite, but after flowering the ovary stalks elongate (they're called podogynes, but it's not clear to me why they're not simply called carpophores) so each fruit is separated from the others of its flower cluster.
Ruppia megacarpa fruit and top of podogyne (scale 1mm)
Ruppia megacarpa was first described from New Zealand specimens, by the late Ruth Mason.  The fruits look like little birds' heads when they're ripe.  Early on, they have a fleshy outer layer; what's left after that's gone is endocarp (equivalent to the outer part of a peach stone) and a single seed inside.  According to Flora of New Zealand Volume 2 (Moore & Edgar 1970), R. megacarpa is found in both North and South Islands in brackish and saline lagoons and ponds.

Moore, L.B.; Edgar, E. 1970.  Flora of New Zealand, Volume 2.  Government Printer, Wellington.

Tuesday, 22 January 2013

Wednesday wildflower: moth plant

Moth plant isn't something I've noticed before, but this week I'm holidaying on Waiheke Island and seeing quite a few northern weeds.  Moth plant, Araujia sericifera, is one of these.

It's a twining climber that smothers shrubs and trees.  Moth plant was introduced probably as an ornamental, but like many it has escaped to become an environmental nuisance.  It's native to South America, although might have been introduced here from Europe, where it is cultivated.

The quite large (about 20-25 mm diameter) fragrant flowers are pollinated by moths, among other things.  It's also known as "cruel plant", seemingly because the petals close around pollinating moths at night and release them in the morning.
Parsonsia heterophylla flowers.  Scale = 5mm.

Our only native member of its family, Apocynaceae, is Parsonsia, with three species.

Thursday, 17 January 2013

The great Veronica hunt part 3.

Some Veronicas aren’t elusive, in fact they’re commoner than most people would like, i.e., they’re weeds.  V. serpyllifolia is one of those, but it’s so discreet most people will never have noticed it.  It grows in lawns and pastures, often where it’s damp, but because the plants are small, straggle through the grass, and have tiny pale flowers, most people aren’t familiar with it.  Even in the herbarium collections it’s not well represented, although probably common throughout the country.
Veronica serpyllifolia, Hunterville: too perfect?

This obscurity also means it’s a hard plant to photograph, so although it’s easy to find, it’s hard to find suitable subjects for a habit photo.  (Habit is the botanical term for the overall appearance of a plant or part of a plant.)  Today I struck it lucky.  A single plant was growing in bark mulch outside a coffee shop in Hunterville.  This plant had no competitors, although it was close to a planted Muehlenbeckia axillaris.  Without competitors, it had grown into a compact, rather symmetrical, leafy disk, and the shapes and arrangements of the stems, leaves, inflorescences, and flowers were all visible.
Veronica serpyllifolia, leaves and inflorescences.
The shop owner was surprised when I asked her permission to take a sample for the herbarium, and came out with me to see what the fuss was about.  It turned out she had noticed the plant and rather liked it, so I didn’t take much.

Tuesday, 15 January 2013

Wednesday wildflower: the great Veronica hunt part 2.

There are good field days and there are bad field days.  Yesterday was a very good one.  This summer I'm collecting introduced Veronicas to photograph for the new Flora treatment.
Veronica catenata, Himitangi Beach.
I needed to go back to Palmerston North to collect the plants I'd left there last week, so I took advantage of the trip to stop off near Himitangi Beach where Veronica catenata has been collected once.  I hadn't seen specimens, but going by the description it's very similar to V. anagallis-aquatica.  My plan was to start at Foxton beach and follow Wylie's Road, which runs parallel to the shore, looking in drains along the way.
The coast between Foxton Beach and Himitangi Beach (Google Maps/Google Earth).
Right at the beginning of Wylie's Road, at the south end near Foxton Beach, is a small lake and a drain on the other side of the road: a likely spot.  And as soon as I got out of the car, I was looking at little pinkish Veronica flowers among the sedges.

Veronica scutellata, near Foxton Beach
The stems were slender and tangled, the leaves were very narrow, and the delicate inflorescences already carried rounded fruits on slender pedicels.
Veronica scutellata flower, the best of numerous field photographs.
But the flower seemed too wide open and the bracts were definitely too short for this to be V. catenata.  Then I noticed there was mostly just a single inflorescence for each leaf pair, and realised I was looking at V. scutellata.
Veronica scutellata fruit.
It's very difficult to photograph, especially in the wind, so I stuffed some into a box to do at home, but unfortunately the flowers closed in the dark, and they rather collapsed.  I've put some in a glass of water on the kitchen window sill to see if they'll open later.

I drove on towards Himitangi, stopping at every likely drain.  Nothing!  Almost ready to give up, I stopped past a rather stagnant-looking drain and culvert and walked back.  There were very tall Veronica plants, looking very like V. anagallis-aquatica.

Large plants of Veronica catenata growing in a drain near Himitangi Beach
Since I'd already photographed V. anagallis-aquatica last week, I thought I would just quickly get a few more shots of its growth form and habitat.
In V. catenata the bracts are longer than the pedicels
But then I noticed the plants had the darker and slightly glossy leaves, smaller rounded, pink flowers, and long bracts of V. catenata.  

Veronica catenata flowers
But not a single fruit to be seen, suggesting this might instead be the semi-sterile hybrid (V. anagallis-aquatica x catenata) that is common in Europe.  This needs to be followed up, something for another Veronica hunt another day.

Friday, 11 January 2013

The great Veronica hunt, part 1.

Veronica anagallis-aquatica.
My main current work task is a Flora treatment of the genus Veronica, which has 17–18 naturalised species and over 120 native ones.  We've revised the native species in a series of monographs of the previously-recognised New Zealand genera (Hebe & Leonohebe, Parahebe, Heliohebe, Chionohebe; and here's why I treat them all as Veronica now) and the naturalised ones were treated by Bill Sykes in the 1988 Flora.  Since then a couple of additional species have been found in the wild, like V. peregrina at Kakariki, near Bulls (that's a locality, not a commensal association).

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.
So I moved on to Kakariki, where fortunately I had excellent directions for the locality where Veronica peregrina had been found, in silty hollows alongside the Main Trunk Railway line.  To cut a long story short, I spent at least an hour there in the hot sun, sweat running down my face from under my hat, and found nothing.  But there were some interesting little plants among the dried up moss.

Linum trigynum, Kakariki.
This little yellow flax was one.  New Zealanders will balk at hearing this called flax, but our large monocot Phormium is called flax only because of its linen-like fibres, and true flax is the genus Linum.

Traveller's joy, Clematis vitalba.
There was a small patch of old man's beard or traveller's joy in flower, and again here's a common name question.  Old man's beard also applies to the lichen Usnea, but traveller's joy seems too benign a name for this nasty invasive climber.

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.
The first plant I saw there was a vigorous and extensive population of horsetail, Equisetum.  This odd fern genus has a world-wide native distribution except New Zealand and Australia and it's an unwelcome invasive introduction.  I know, it doesn't look like a fern, but it does belong in a large grouping that includes the "true" ferns, which are distinctive because of their pinnate spirally-unfolding leaves and thin-walled spore capsules.
Equisetum arvense, Kakariki.
The leaves are high in silica, so it used to be used as an abrasive, e.g., for scouring pots.  A friend tells me the violin-makers at Cremona use it to gently abrade the lacquer layers in violins between coats.

Veronica, Rangitikei river bed at Kakariki.
Across the river I found the wet silt I was looking for, among stones on the river bed.  And here was a Veronica, not V. peregrina, but one of the aquatic species that I hadn't photographed before.  Within the small population there were plants with pink flowers and plants with mauve flowers.  Flower colour is said to distinguish V. catenata (pink) from V. anagallis-aquatica (blue).  This looked to me like a polymorphic single population, but I guess there could be two species growing together.

Mauve and pink flowered plants of Veronica anagallis-aquatica, Rangitikei River at Kakariki.
There were other differences.  Some of the mauve-flowered plants had glandular cilia on the capsules; the pink one had glabrous capsules.  The Flora says glandular-ciliate for V. anagallis-aquatica, ciliate for V. catenata.  No plants had the spreading pedicels said to be characteristic of V. catenata.  I'm going to go with V. anagallis-aquatica for all these plants for now, but to use different collection numbers for the pink and mauve ones, so they can be separated later if need be.

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.