Skip to content

2

Did anyone guess what the mystery seeds were last week?

I started you with a tricky one, because it is only found in the desert. Common names for these plants are barrel cactus and fishhook cactus. The scientific name is Ferocactus.

The name fishhook cactus comes from the fish hook shape of the spines of certain species. I have read that the American Indians of some tribes did use them for fish hooks.

It is also called the compass cactus because in natural settings the shady side grows longer and the cactus tilts to the South.

The flowers are sources of nectar and pollen for bees.

The bright yellow fruit are supposedly eaten by deer and certain rodents.

For more about the special relationship between ants and barrel cacti, see my Wild About Ants blog.

This week's mystery seed:

The shiny, hard black seeds of the barrel cactus reminded me of the seeds of another plant in our yard. This time I'll give you a hint. The mystery seeds this week might be easier for our Australian friends to identify.

For more about cacti see:

It is cold (for us) and windy this morning, and I wasn't sure I'd be able to find a bug of the week. No fear, there's always something going on in the insect world.

barrel cactus

First I checked our barrel cactus, which is covered with yellow fruit.

barrel cactus

As I got closer, I spotted a beige patch near the base of one of the fruit towards the right/center of the photograph. You'll be able to see it more clearly in the next photograph.

cactus

The biege patch looked soft and furry, with some yellow and orangish bumps.

ants at extrafloral nectaries

Ants were visiting those bumps in a purposeful way. First they would arrive looking slender.

ants at extrafloral nectaries

After spending some time with their heads near the bumps their hind portion, called a gaster in ants, would start to swell up.

ants at extrafloral nectaries

These ants are feeding at the extrafloral nectaries of the cactus. Nectaries are parts of a plant that produce the sweet juicy nectar. Many are found inside the flower of the plant. These structures are called extrafloral because they are outside of the flower.

Why does a cactus supply liquid sweets in the form of nectar to ants, especially in the desert where water is in short supply? There are several theories, including that ants increase the fertility of the soil around their mounds and ants are more likely to nest nearby when food is available, and/or that ants feed on insect pests while on the cactus. In any case, it is a fascinating example of just one of the complex relationships between ants and plants.

Thinking of sweets makes me want to have a cup of hot chocolate...