Saturday, November 24, 2018

Goldenrod Study

             Here I am looking at the size of the flower head compared to the length of the stem. The stem was broken off about 5 cm from ground level. Yes, there is snow on the ground already this November and all the leaves of this plant are gone.

            Because I started my study late in the season some of the flowers were well past their prime. This is a group of flowers on one stem.

            Looking closer one can see more of the individual flowers. Each flower is made up of 3 to 7 disc florets, 10 to 15 strap florets, and surrounded by 14 to 16 phyllaries.

            The entire flower is only 2.5 to 4.5 mm tall. For comparison, a dime is about 1 mm thick and, if you have saved any, a penny is about 1.25 mm thick.

            Here I used a scalpel to split a flower in two pieces. You can see two disc florets, parts of three strap florets and parts of two phyllaries as well as some of the pappus, i.e. the hair like appendages.

            In this photo one can see some stigmas from the ray florets waiting for pollen to come in to fertilize the pistil hidden below. Ray florets have only female parts. Disc florets have both male parts for producing pollen and female parts for producing seeds. I also just learned that goldenrod plants can not fertilize their own flowers. They have to get pollen from another plant via some insect. Pollen is too heavy to move by air which is why one cannot get "hay fever" from goldenrods.

            Very close up photos from the microscope showing the relative sizes of two disc florets. The numbers are for comparison only and do not stand for any real measurements.

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