The St. John's-Worts: Under-Rated Landscape Plants
We have several species of St. John's-wort that have planted themselves on our property from groundcovers in our lawn to this shrub with its small yellow flowers, gracefully arching stems and reddish peeling bark. Recently, I decided that it was time to identify which Hypericum it is. So I carefully observed the flowers:
If you're serious about identifying Florida's plants, "Guide to the Vascular Plants of Florida" by Richard Wunderlin and Bruce Hansen, is THE authoritative text. These plant taxonomists are also the experts that provide data for the online Atlas of Florida's Vascular Plants, which we often cite as our authority for mapping which counties plants occur and when identifying whether a plant is native or not.
Here is their list of Hypericum for Florida. Without the book, you could link to all 31 of the species, look at the photos, and try to decide, but the photos may or may not provide enough detail to correctly ID the plant. The book and its keys make the job of figuring out the species or subspecies more certain.
A good key provides a series of clear either/or choices.
#1 is easy to figure out the number of petals and sepals. There are obviously 4 petals, but I only saw two sepals without my magnifying glass, but still I had to choose the first #1 with 4 petals--not 5.
#2: Styles 2 or styles 3 or 4. I can see that there are 2 styles, so I pick the first #2.
#3: The pedicels (flower stems) are short the the 2 bracts are right under the sepals (calyx). So my shrub is Hypericum hypericoides or St. Andrew's cross. When I look it up on the online plant Atlas, the range covers the whole state and the photos match my shrub perfectly. So now I know what to call my beautiful shrubs.
In order to successfully use a key, you'll need to learn (or re-learn) the parts of the flower and some other botantical terms. But once you get started, it's rewarding to know exactly what you have.
When you purchase "Guide to the Vascular Plants of Florida" or any of the other books listed in the right-hand column, by clicking our links, FNPS earns a small amount of money. Thanks for your support.
Ginny Stibolt
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| A St. John's-wort shrub planted itself in front of the palmettos, but which Hypericum is it? |
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| 4 petals in a flattened X-shape and 2 large sepals |
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| Turning the flower upside-down, the 2 large sepals are subtended by 2 narrow bracts |
Here is their list of Hypericum for Florida. Without the book, you could link to all 31 of the species, look at the photos, and try to decide, but the photos may or may not provide enough detail to correctly ID the plant. The book and its keys make the job of figuring out the species or subspecies more certain.
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| Here is the key in the Wunderlin and Hansen book where I knew I could figure out our shrub. |
A good key provides a series of clear either/or choices.
#1 is easy to figure out the number of petals and sepals. There are obviously 4 petals, but I only saw two sepals without my magnifying glass, but still I had to choose the first #1 with 4 petals--not 5.
#2: Styles 2 or styles 3 or 4. I can see that there are 2 styles, so I pick the first #2.
#3: The pedicels (flower stems) are short the the 2 bracts are right under the sepals (calyx). So my shrub is Hypericum hypericoides or St. Andrew's cross. When I look it up on the online plant Atlas, the range covers the whole state and the photos match my shrub perfectly. So now I know what to call my beautiful shrubs.
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| Flower diagram from wiki-commons |
When you purchase "Guide to the Vascular Plants of Florida" or any of the other books listed in the right-hand column, by clicking our links, FNPS earns a small amount of money. Thanks for your support.
Ginny Stibolt
Comments
V. Avery
Use caution in using the Atlas maps as an authority for what counties plants appear in. The maps account for only VOUCHERED specimens and I can attest to Osceola County plants being severly under-represented as I live adjacent to natural conservation areas and many of the plants found aren't listed for our county.
Ginny