Mosquito eaters

The sundew plants in Sundew Bog are miniatures. My guidebook gives their height as from 5 to 25 cm., but that includes the tall flower stem. The leaves form a basal rosette under 5 cm. wide, and mostly less than 1 cm. above the moss or mud they grow in. Walking through the bog on the plank walkway, you may not even see them, unless you get down on hands and knees. Then they're everywhere.

No, not these; this is the Sphagnum moss (S.  fuscum, probably) that holds the water that the plant relies on.

And here's one plant. The leaves are 6 to 12 mm. long.

A few of the larger leaves.

One leaf, loaded with sticky "dew".

About that dew; it contains sugary nectar to attract insects, and a glue to trap them. Once an insect touches one tentacle (they call them tentacles, but they're stalked glands) the ones close by bend over to strengthen the trap. Then the third component of the dew, a group of enzymes, dissolve and digest the insect, releasing its nutrients to be absorbed by the surface of the leaf.

Insects form an essential part of the sundew's diet; the roots serve mainly to anchor the plant and take in water, but the boggy soil is nutrient-poor. This species, Drosera rotundifolia, can host fungi which can help collect food. 

The sundew likes mosquitoes. We didn't see a single mosquito in the bog. I did see a few trapped flies.

Oh, and the soil of a bog is acidic. And sundews are oxylophytes, a nice word I picked up from E-Flora, meaning any plant that likes acidic soil. From oxy- (“acid”) +‎ -phyte (“plant”).

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Las plantas de Rocío del Sol en el Pantano Rocío del Sol son plantas minúsculas. Mi libro guía dice que miden de 5 a 25 cm. de altura, pero incluyen en esto el tallo largo de la flor. Las hojas forman una roseta basal midiendo menos de 5 cm. horizontalmente, y en su mayoría, se alzan menos de 1 cm. sobre el musgo o el lodo donde crecen. Caminando por el sendero de madera que cruza el pantano, puede ser que no veas ni una, a menos de que te pongas a gatas. Y entonces las verás dondequiera.

1. No, aquí no hay Rocío; este es el musgo esfagno que retiene el agua que requieren los Rocíos del Sol.
2. Una planta de Rocío de Sol. Las hojas miden de 6 a 12 mm. de diámetro.
3. Unas hojas de las más grandes.
4. Una sola hoja, llevando sus gotas de "rocío".

Acerca de ese "rocío"; contiene néctar azucarado para atraer a los insectos, y un mucílago pegajoso que los atrapa. Cuando algún insecto toca uno de los tentáculos (los llaman tentáculos aunque no lo son; son glándulas), los que están cerca se doblan hacia el insecto para cerrar la trampa. Entonces el componente tercero del rocío, un grupo de enzimas, disuelven y digieren el insecto y la superficie de la hoja absorbe las sustancias nutritivas.

Los insectos son una parte esencial de la dieta de esta planta; las raices sirven principalmente para fijar la planta en su sitio y para absorber agua, pero el suelo del pantano provee pocas sustancias nutritivas. Esta especie, Drosera rotundifolia, puede asociarse con un hongo, lo cual puede añadir algunos nutrientes.

Al Rocío del Sol le gustan los mosquitos, que son una plaga aquí todo el tiempo de calor. Y no vimos ni un solo mosquito en el pantano. Vi algunas moscas atrapadas.

Una cosa más. El suelo de un pantano es ácido. Y los Rocíos del Sol son oxilófitas, una palabra nueva para mi, que significa cualquier planta que prospera en suelos ácidos. Viene de oxy- (“ácido”) +‎ -phyte (“planta”).

Beautiful and deadly

Ma Nature is always full of surprises. Take my humble London Pride; it has turned out to be a most efficient killer.

After I found the dead flies and aphid on the stems, I decided that I must investigate further. The next afternoon, I collected a few critters from the garden; a pill bug, a centipede, a millipede, an ant, a tiny plant bug. I put each one in a plastic container with a few stems and flowers of London Pride, and watched to see what would happen.

2 mm. bug, on broom stalk.

A sad sight; the centipede touched a stalk, and immediately started to writhe, then slid off to one side and lay trembling all afternoon and evening. The pill bug walked over one stem, and spent the rest of the afternoon grooming himself, cleaning the glue off his legs and antennae. So did the plant bug. But the millipede died in a couple of hours. A second one died the same way; a control in a container with no London Pride was fine. Only the ant was unaffected.

London Pride flower, with trapped aphid

I watched a couple of aphids on a stem; they were alive when I first saw them, but completely stuck to the red balls. They struggled to release one leg, only to have another touch down and be trapped; more attempts  left them attached by antennae, body, and legs.

This all brought up more questions; the aphids probably died due to being glued, and having their breathing spiracles clogged. But the millipedes? They hadn't seemed to struggle at all, and had left the stalk long before they died. Was the plant poisoning them?

I asked Google; an image search was most helpful. I found many plants with similar structures, many more than I would have expected. Of course there were the carnivorous sundews, with their beautiful, deadly traps, large enough to see without a lens. Compare these:

London Pride flower stalk.

... with these:

Sundew Drosera capensis. Image from Wikipedia. By Noah Elhardt.

Small prey, mainly consisting of insects, are attracted by the sweet secretions of the peduncular glands. Upon touching these, the prey become entrapped by sticky mucilage which prevents their progress or escape. Eventually, the prey either succumb to death through exhaustion or through asphyxiation as the mucilage envelops them and clogs their spiracles. Death usually occurs within one quarter of an hour. (Wikipedia)

I was surprised to find how many other plants are protected the same way. The list includes geraniums, squash, the mint family, rosemary, coleus, tobacco, some peppers, catnip, roses, potatoes, tomatoes, and more.

The glue sticks are called glandular trichomes, or hair-like appendages that produce enzymes or essential oils. Some of these oils are toxins, others attract insects (and cats), some are glues.

Glandular trichomes on potato and tomato leaves release phenols and phenol oxidizing enzymes which react to form a sticky substance which hardens to entrap small–bodied insects.  Aphids, for example, get coated with sticky phenols when they land on these plant surfaces.  In the struggle to escape, they disrupt a second type of trichome which releases polyphenol oxidases (PPO). The PPOs oxidize the phenols into quinone, entrapping the aphids like hardening of cement, resulting in its death.  (Plant Glandular Trichomes)

Oh, the pill bug, ant, centipede and plant bug? They recovered once they were away from the London Pride, and I released them and the control millipede, with my apologies for the trouble I had caused them.

Treasure Hunt

We read about them in Lulu Island Blog: sundews. The last time I had seen any in the wild was 20 years ago, in the mountains above North Vancouver. And these were right close by, in the Richmond bog. We had to go and find them.

I didn't have high hopes; they are tiny, elusive plants and the bog is big. But we would enjoy walking there, whether or not.

We started at the Richmond Nature House, off Westminster Highway. Signs outside warned us: no dogs, no bikes, no feeding the animals. Do not pick the plants, not even berries. And no smoking; bog fires are easily started, hard to put out.

In the Nature house, a very small boy was watching a very large garter snake in an aquarium. He (the snake) was flicking a red tongue out at the boy; when Laurie peered over the top, the snake rose up to investigate, sticking the tongue out even more, an inch or more. The tip was forked and black.

On to the trails. Fireweed, birch, twisty pines, salal, the occasional mountain ash. And acres and acres of blueberry, mostly the invading high-bush blueberry, quite a bit taller than it was the last time we walked there. Underneath, the Labrador tea struggles to maintain its foothold.

Blueberry. Beautiful, but invasive.

Over the pond, dragonflies danced. The tiny blue damselflies with the brilliant head and rear end, some sturdy-looking brown dragons, and one of the blood-red meadow-hawks that I had seen before by Crescent Beach. Try as I might, though, I could not get a photo; I would focus the camera on what seemed to be a favourite spot for them and wait. They would be elsewhere. As soon as I turned to where they were now, they went back and parked at the old spot. I'm sure they do it on purpose.

Pond. No dragonflies.

But we were looking for sundews. I kept my eyes mostly on the ground at the sides of the trail. There were tiny flowers, several kinds. You have to look closely at this next photo, taken down at the base of the reeds, to see the flowers; some kind of miniature shooting star. (Update: Hugh Griffith -- see comments -- identifies it as a cranberry flower. Thanks, Hugh!)

Mosses. Pale green spagnum, and this rose-coloured mat.

'shrooms. Several varieties, mostly deep in the underbrush. This one was just beside the path.


Looking up for a change, I saw a bleeding tree, with tiny trapped flies.

And, yes, we found the sundew! One small patch, a few feet across, 1/2 inch high, hiding among mosses and grasses. Almost invisible, but there it was.



The day was hot and dry; even the bog paths were dry. But when I sat on the moss to take these photos, I found out that the water table is barely finger-nail deep. The sundews' roots -- I tested -- sit in soggy soil. And they pull that water up to the tips of their leaves, and stand there looking dewy-fresh, even in the heat of the day. All done in order to trap unwary insects, coming for a drink, only to be eaten.

It's a dog-eat-dog world. But beautiful, in spite of it.