How small can flowers get?

A few weeks ago, I blogged about the plants we saw on a short walk along the coast south of Makara.  This week, I had the opportunity, courtesy of Meridian Energy, to visit two bays a bit further south.  I was with Heidi Meudt (Te Papa botanist), Jessie Prebble (PhD student), and Ewen Robertson (Environmental Compliance Specialist with Meridian), and we were looking for one of New Zealand's smallest plants.

Te Ikaamaru Bay and Ohau Bay are on Terawhiti Station, but access by road and 4WD track is through Meridian Energy's wind farm of 62 giant turbines.

Much of Terawhiti Station is returning to forest, and the intermediate stages are dominated by mostly native shrubs: manuka (Leptospermum scoparium), tauhinu (Ozothamnus leptophyllus), Olearia solandri, coprosmas, and small pockets of introduced gorse and Darwin's barberry.  Pale yellow native clematis was prominent among the scrub. Goats are common, and the understory commonly features the giant nettle ongaonga (Urtica ferox).

Te Ikaamaru Bay

The tiny plant we were seeking is Myosotis pygmea var. minutiflora, now treated by many botanists as a separate species, Myosotis brevis.  One of the aims of Heidi and Jessie's research is to test whether it's a "good species", that is, whether the evidence indicates it's a separately-evolving lineage from its relatives.

Like many native forget-me-nots, it's rare, though it's easy to see why it's often overlooked, so it might be more common than we think.  We had records of it growing in both bays, on coastal turf of Selliera radicans and Leptinella dioica.  And that's just where we found it, wherever the soil was a bit peaty.

Myosotis brevis

Myosotis brevis is so small that you need to first find the habitat, then get down on your hands and knees to find it.  Even then, we might have missed it but for the tiny—no, minuscule—flowers (the world's smallest flower is the tiny duckweed, Wolffia, where the whole plant is about 1 mm across and the flower is about 0.25 mm).

Myosotis brevis, the flower is about 1 mm across.

Forget-me-not flowers are mostly blue in other parts of the world, but nearly all of ours are white, cream, yellow, or rarely brownish.  Interestingly, there are two blue-flowered ones in the Subantarctic Islands, where other plants have brightly coloured flowers too. The creamy flowers of M. brevis are about 1 mm in diameter.  Do they self-pollinate, or is a tiny pollinator required?

On the cliffs at the headland, we found some Peperomia urvilleana.  This tiny pepper relative makes a good indoor plant, but here it thrives in the open, exposed to salt spray.

Peperomia urvilleana

The oystercatchers were making a racket.

Oystercatchers among cape weed, Arctotheca calendula.

No wonder; they were sitting on their second clutches of eggs. I saw one ferret, so I guess life's tough for oyster-catchers.

There were plenty of other native small-flowered plants, like Limosella lineata...

Limosella lineata

... Dichondra repens, here being visited by an ant, ...

Mercury Bay weed, Dichondra repens

... and Colobanthus muelleri (seed capsule top centre).

Colobanthus muelleri

An odd plant for me, because I had only seen it once before, was a thistle-like member of the carrot family (Apiaceae).  This is Eryngium vesiculosum.

Eryngium vesiculosum

Ohau Bay.  Coastal turf along the tops of the low cliffs.

At Ohau Bay the coastal turf is quite extensive along the top of a short eroding cliff, between a stagnant ponded creek—which has lost its way among the piles of driftwood—and goat-infested pasture inland.  There were plenty of introduced weeds among the turf, but Myosotis was mostly in the pristine bits.  Even the weeds are mostly small-flowered.

Pearlwort, Sagina apetala. That's an open capsule, not a flower

Sand spurrey, Spergularia rubra

Field madder, Sherardia arvensis