How to read a binary key?

Discussion in 'Plants: Science and Cultivation' started by wcutler, Jun 13, 2021.

  1. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    I can't search on the word "key" here, so I'm not sure if there is a thread on this. I don't understand how to read the eFlora keys. Is there an explanation somewhere of how they work? For instance, here is what I want to understand:
    From Opuntia in Flora of North America @ efloras.org:

    5 (4) Areoles in distal 1/3 of stem segment bearing 0(-1) spines, spines absent from basal 95-100% of stem segment; fruits spineless 30 Opuntia aurea
    +
    Areoles in distal 1/3 of stem segment bearing 1-4 spines (spines absent from basal 50-80% of stem segment); fruits spiny (6)
    On the left, I think I understand that this is item 5 and it came from 4. And the + is another option.
    It's on the right I don't understand. What is the difference between 30 and (6) with the brackets? If the text on the first item is satisfied, then it's Opuntia aurea, and we're done, is that right? So what's the 30?
    I assume the (6) is: go to 6.
     
  2. Sulev

    Sulev Well-Known Member

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    30 is the result of the species identification. Finished identification sequence. The number is of the species in the genus.
    (6) is the next step for not finally identified species.
     
    Last edited: Jun 13, 2021
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  3. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Thanks, Sulev. So I can ignore that, which really is a big help. But if I wanted to understand it, does it refer to a list somewhere, in which it's number 30?
     
  4. Sulev

    Sulev Well-Known Member

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    If you click on the name of the identified species, the you will be redirected to the description of the species, and that always starts with this number. Every species in every genus has unique number inside the genus. These numbers start from 1 and end with the number of species in the genus. I don't know if species are somewhere listed together with these numbers. If such list exists, then it must be list of species in genus, as those numbers are not unique at higher level.
     
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  5. Ron B

    Ron B Paragon of Plants 10 Years

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  6. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Thanks, Ron. I don't know if I have clicked the Help link before. It doesn't explain where the 30 in this instance comes from and that I can ignore it (or what its use is), but there is this, which is helpful, since they're in alphabetical order:

    8. How can I search for all species of a genus?
    In the "name" box, type the name of the genus followed by the wildcard "%"​
     
  7. Ron B

    Ron B Paragon of Plants 10 Years

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    Sulev explained the 30 upthread - Opuntia aurea is species #30 within this treatment of Opuntia. Otherwise any item within the key that is shown in green is a hyperlink to another place in the key or elsewhere. So after you followed the key to 30 Opuntia aurea you would click on this binomial presented in green to see the full account provided for that species on another page.

    As far as finding all the species in the genus is concerned in this case you are already on the Opuntia main page. With links to all of the individual species accounts. With how I start off with a genus level page in this work is by searching "[genus name] efloras flora of north america" using a browser.

    By the way they aren't done yet so not every North American genus comes up when searching for it in eFloras Flora of North America.
     
    Last edited: Jun 13, 2021

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