Flower visitors

Sorting through garden images for a talk, I came across these impressive-looking flower visitors. They were visiting what appear to be asters in a Portland garden last September.

This one seems to be some sort of unusual bee or hornet relative.


And this one looks more fly-like. Let me know if you know their real identity! I'm looking forward to spring, and watching more flower visitors....

An unexpected flower

Crape myrtles (Lagerstroemia indica) are everywhere in the Southern U.S.; they're used (overly so) as street trees, in home landscapes, in commercial landscapes, etc. Brought to the Carolinas by botanical explorer Andre Michaux, they're attractive in flower, have lovely bark and architectural shape, and are TOUGH.

But, I've never thought too much about them, because I haven't see many insects or birds using the flowers or eating the fruits or seeds. They weren't high on my 'plants that work for a living' list.

But checking plants near the potting bench this morning, I kept hearing a couple of hummingbirds twittering and whirring high up in the crape myrtle nearby. Were they eating small insects attracted to the flowers? Were they annoyed with me because I was near one of 'their' feeders?

What's going on with crape myrtle flowers anyway?

First I checked for nectar (none), then looked at some open flowers, and noticed a couple of honeybees collecting pollen at the center of the flower. A few Google searches later, and I found out that Lagerstroemia flowers produce two kinds of anthers (the pollen-producing structures), the fertile 'real' pollen is produced by the longer peripheral anthers, with the 'attractant' pollen produced by the central clusters of anthers.

One of my 'hits' was a research paper that had determined that the composition of the two pollen types was different too, the 'real' pollen being higher in sucrose, whereas the 'food' pollen had a balanced amount of glucose and fructose. These researchers (this was an abstract from a 2003 article in Plant Biology) looked at lipid composition, too, but I wasn't able to read the full paper online.

I also 'hit' on an interesting site that has most of Charles Darwin's correspondence posted.

He exchanged letters with almost 2000 people during his lifetime. Apparently, Joseph Dalton Hooker (a notable botanist of the time) had given Darwin a Lagerstroemia indica, suggesting that he'd find the flowers interesting. And Darwin had indeed, corresponded with a botanist at the Royal Botanical Garden at Kew about the flowers.

Looking at the flowers again, I saw a small bee collecting pollen from the fertile anthers, the hummingbirds were still up in the tree, and I had a totally different perspective of an 'ordinary' garden flower.

Flower visitors

I enjoy watching flower visitors. Are they collecting nectar or pollen (or both)? How are they visiting the flowers? Many are effective pollinators, transferring pollen between flowers, but not all are.

This bumblebee was sonicating ('buzzing') horsenettle flowers (Solanum carolinensis) to discharge pollen. Then, they take the pollen back to provision underground brood cells. About 8% of the world's plant species require 'buzz pollination' to effectively transfer pollen to stigmas.

Some large bees (such as this carpenter bee) 'rob' the nectar of available flowers, such as this Salvia, poking a hole in the base of the flower (corolla) tube.

Butterflies rely on nectar for a source of energy as adults, some getting energy from rotting fruits. Some will collect salts and minerals from shallow puddles, dung, or salty spots. Here's a silver-spotted skipper visiting a bee balm flower for nectar, getting an energy-rich boost.








Photo note:
My gardening companion took the horsenettle and bee photo, and a fellow educator just sent me the photo of the skipper visiting bee balm.