Slatsz Wildflower Walks 2013 #1: September 5, 2013 – Centaurea diffusa, Conyza canadensis

It was overcast and evening. The light was double weak. But my legs needed work so … go.

I was out an hour and forty five minutes but I probably only walked twenty to thirty minutes and I had to make a point of getting in that much walking. There were several up and downs. That counts as legs workout.

I made 168 images but only found 44 keepers. Shutter speeds were almost never fast enough for true hand held photography. I almost always had to contrive a brace for the camera. I did not often succeed.

I saw some Centaurea diffusa, diffuse knapweed, on the drive past the north side of the park and took specimens.

I drove to the fireplug on the south side of the park and set up the back of the car for macro photography.

I put a lot of effort into getting useful images of Centaurea diffusa and I seem to have got lucky. It really was luck because too much of the time I couldn’t see what I was trying to photograph. I just take a chance and hope for the best.

There was a very healthy if short Conyza Canadensis, Canadian horse weed, growing from the crack between the concrete curb and the asphalt of the street. My problems with getting good ‘plant photos’ persisted.

I was headed for the north side of the little grove marking south pond where I should find the Bidens vulgata, tall beggar tick, that I wanted to photograph but the luxurious patches of Eriogonum niveum, snow buckwheat caught my eye.

I settled in and did a lot of images but not with a lot of success.

While sitting there I noticed that there were Polygonum douglasii, Douglas’ knotweed, all around me so I worked, once again, at getting a full front shot of a blossom. I got out my tape measure to demonstrate the small size of the blossom.

By the time I did all I wanted to do with the Polygonum douglasii I forgot I was interested in Bidens vulgata and set out to get some work for my legs.

There were Grindelia hirsutula, curly cup gumweed everywhere, many reduced to autumn rosettes, a few with good blossoms on them. I took a plant photo but didn’t spend time with the plant till later.

It was quite late and the light was, of course, very weak. I decided to see what I could do with seed heads of Perideridia gairdneri, even so.

I did what I could do with them and worked awhile with Grindelia hirsutula.

I walked down to slatsz’ stump and long rock ridge just to be doing it, returned to the car and headed for Skippers and a bowl of chowder for a little unwind.

THE PHOTOS

10 Centaurea diffusa, diffuse knapweed – Asteraceae

110-190

Introduced plant

Burke lists ten Centaurea in Washington state. All are introduced. The most familiar Centaurea is Centaurea cyanus, bachelor button. They are still in bloom around the park but they are not in good shape.

110-120 The leaves of this specimen look much simpler than the leaves of the photos in Burke. I need to look at the leaves of several plants some time and record differences.

140 This inflorescence looks snow white. I’ve decreased the mid-tones to bring out detail. The yellowish structures are disk flowers. I suppose the petal like structures are the ligules of ray flowers. I need to verify that.

160-170 I’ve decreased the mid-tones further. The petals of the corolla tube of the disk flowers are easily seen.

176 Burke says there are dense bristles on the receptacle without further explanation.

178 A disk floret.

The base of the floret is the cypsela, which contains or will contain a seed. [A cypsela is an achene from a floret with an inferior ovary.]

Burke says the pappus, the bristles that become a parachute on the dandelion and other Asteraceae are ‘wanting’. There are bristles at the top of the cypsela.

The corolla tube with its flaring petals rise from the cypsela. The anther tube rises above the petals of the corolla tube. The style tube rises from the anther tube. I suppose the stigma is the region above the collar like structure, I don’t know that. If the stigma opens, curling back as it does on other Asteraceae, this one has not opened, as yet. Something else to watch for.