Tom's Blog

Tuesday, September 16, 2008

More goldenrods (gray, zig-zag)

On a brilliantly sunny day like today, the goldenrods literally glow with color. Two more goldenrods now at peak are gray goldenrod (Solidago nemoralis) and zig-zag goldenrod (Solidago flexicaulis). Despite the fact that these two have entirely different habitats (gray likes dry prairies; zig-zag likes shady woods), the specimens in the photos here were only three feet apart. (I think this shows how important microclimate is in controlling the distribution of prairie and woodland plants.)

Zig-zag goldenrod is one of the latest goldenrod species to flower, but it is one of the earliest plants to appear in the spring. Not long after the spring ephemerals are blooming, vegetative growth of zig-zag goldenrod can be seen. The plant grows mostly low to the ground for a month or so, and then probably goes into summer doldrums. Once days start getting short, it sends up flower stalks (which are somewhat zig-zag, hence the common name). I assume that it is a typical short-day plant, not initiating flower buds until the days start to get short. Zig-zag goldenrod is one of a few goldenrod species which has flowers up the stem, rather than in a flowering head at the top. (See photo above)

Gray goldenrod is sometimes called "nodding" goldenrod, because its flower head hangs to one side, appearing to be nodding. It is a short goldenrod and most common on dry prairies, where it can compete well because most other species are short. There are several subspecies here, and I'm not sure which one we have. All of our stock is derived from a single population that was native to the original dry prairie remnant (Unit 1).


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