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.


  1. Hiya Phil, I did my PhD on this beast in the UK. It's a pretty big weed problem over in Europe. It's certainly popular with bees, I once rescued two large bumblebees stuck fast down the throat of the one flower.

  2. Interesting, thanks Hamish. I remember seeing quite a bit when I lived for a year in Wokingham. It seems to like wet sites. I've never seen big infestations of it here, although there probably are some.

    Did the two bumblebees wedge each other in? There's really only room for one at a time.

    1. I know of a fair bit over on the West Coast, especially on the Kumara-Inchbonnie Road. Yes, both bees wedged in & quite indignant.

  3. This plant certainly has medicinal value. It helps that it is right beside the poison ivy in many areas.