1. These are pictures of Verbesina, one of the most invasive, growing-all-over-the-place alien plants on Midway Atoll. It's like a daisy, since it's in the same plant family.
2. Buy a daisy (or a black-eyed-susan or sunflower) from a florist shop or grocery store.
3. Using a magnifying glass, look at your daisy flower, which is really a "composite flower." Each one of the usually white petals around the edge is actually a real flower.
4. Look at the daisy's yellow central disk. Each one of the little sections in the disk is also a real flower.
5. Now, count the white petal-flowers and all the yellow disk-flowers of your daisy. How many real flowers are there altogether?!
6. It looks as if there are about 6 composite flowers in the first picture of Verbesina. Since Verbesina is very much like your daisy, use the number of real flowers in your daisy to calculate how many total real flowers there could be on just this one Verbesina plant.
7. Look at this second picture, taken on Midway's Sand Island, showing a whole field of Verbesina.
8. Can you try and imagine how many real flowers are there in this field?! And each real flower produces a real seed! And if each seed grows into a new Verbesina plant.... WOW! No wonder Verbesina is called an alien invasive plant! Where can native albatross find a place for nests?!
photo by Forest & Kim Starr
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Here's a picture of me surrounded by thick, tall Verbesina; I'm trying to strangle it!
photo by K. Kam
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| The Number of Seeds in a Verbesina Seed Head | ||
| Seed Head # | Number of Seeds | |
| 1 | 91 | |
| 2 | 104 | |
| 3 | 141 | |
| 4 | 266 | |
| 5 | 164 | |
| total | 766 | |
| average | 153 | |
6/13/10 -- Now that I'm on Midway I've had a chance to look at Verbesina closely. In fact, right above is a picture of a Verbesina seed head. Of course that's the stage in the plant's life cycle after the real flower (or "flower head.") The data table above shows how many seeds were in each of the 5 seed heads I collected. What can you do with this information?
