Tuesday, 19 June 2012

Wednesday Wildflower: ivy-leaved toadflax

Ivy-leaved toadflax, Cymbalaria muralis, Wellington, New Zealand.
Toadflax is the English name for the genus Linaria and its relatives, plants related to snapdragons.  This little creeping one (sometimes also known as Kenilworth ivy) is common on cliffs and walls around Wellington and throughout New Zealand (the species epithet muralis refers to its preference for walls).
Cymbalaria muralis, Kelburn, Wellington, New Zealand.  A, flowers, the one at far right is being gently squeezed with forceps to open its throat; B, leaves, the large one is from a shaded site; C, fruits on their elongated stalks.
 Its leaves are bigger in the shade, and slightly fleshy.  It does well in full sun, although even the sunniest cliffs and walls are usually shaded in either the mornings or afternoons.
Cymbalaria muralis, Karori, Wellington.
There are some interesting features to these little purple and yellow flowers.

First the entrance to the flower is closed by a palate (the two yellow knobs in the flowers above), which must be forced open by the pollinator (usually a bee).  You can play snapdragons with these by gently squeezing the flower tube from the sides, but they're not as spectacular as the true snapdragon, Antirrhinum majus.  They are both classified in the same family, Plantaginaceae (along with a bunch of plants with more open flowers, like Veronica and Plantago).

Secondly, behind the flower is a long nectar spur, which holds the reward the bee is seeking.  The bee needs a long-tongue to get the nectar.  New Zealand has no native long-tongued bees, but introduced bees can pollinate toadflax.  Interestingly, we have no native flowers with closed throats and nectar spurs.

Thirdly, the flowers are held above the leaves, but after they're pollinated the flower stalk curves downwards below the leaves and elongates, holding the developing fruit close to the soil.  By the simple expedient of growing the stalk (probably by elongating cells, especially on one side, to generate a curve) the optimum positions for both pollination and seed dispersal can be achieved.

Ivy-leaved toadflax is native to Southern Europe, and probably came to New Zealand as a cultivated plant, like so many species that are now wild.  It was first reported as naturalized here in 1904 (Sykes 1988). Although it's now classified in the family Plantaginaceae, but for many years it and many of our other Plantaginaceae were considered to be part of the Scrophulariaceae.

Reference.

Sykes, W.R. 1988.  Scrophulariaceae, in Webb, C.J.; Sykes, W.R.; Garnock-Jones, P.J. Flora of New Zealand Vol. 4.  DSIR, Christchurch.

6 comments:

  1. There is a really neat bit of time lapse on David Attenborough's 'Private Life of Plants' that that shows the ivy-leaved toadflax 'planting' itself into cracks and crevices. I don't recall which episode unfortunately.

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  2. Thanks Jarrod; there's an episode called "Traveling", which is all about dispersal, so I guess it could be in that. I'll check.
    Cheers
    Phil

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  3. I did a simple google and found a link to the clip as mentioned.

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    Replies
    1. thanks - fun video
      Just widh there was a good/enviro-friendly way to control it. Round-up gel works well but loathe to use that.

      Delete
    2. thanks - fun video
      Just widh there was a good/enviro-friendly way to control it. Round-up gel works well but loathe to use that.

      Delete