Astros Branch - American Begonia Society

Description - Main Key

This key is a complement to that published by the Smithsonian Institute, Begoniaceae Edition 1, 1984, and Begoniaceae Edition 2, 2002. It utilizes the same mainkey and subkey structure as in the earlier publication, with many of the couplets being the same. Some minor word changes have been made to clarify the leads. Two major additions in this Pictorial Begonia Key are the separation between species (1) by continent of origin and (2) by alphabetical listings. These simplifications are possible because of the much smaller number of species involved. The Pictorial Begonia Key covers over 300 begonia species; those which are currently being grown by ABS members. Of these, we now have good digital color pictures of over half of these. These photos show the plants and details of the leaves and flowers. The other species will be photographed with time.

Alphabetical listing of Begonia pictures with their keys

Main Key (Used to find the species when the name is unknown.)
Note: The subkeys contain the plant and flower pictures.

2-1. Blades peltate Subkey 2-3
2-2. Blades basifixed
    4-1. Blades divided or strongly lobed (cleft, parted or compound)
       5-1. Blade nerves digitate
          6-1. Inflorescence dichotomous at base, exclusive of pedicels Subkey 4
          6-2. Inflorescence not dichotomous at base, exclusive of pedicels Subkey 5
       5-2. Blade nerves pinnate Subkey 6
    4-2. Blades shallowly lobed to entire (entire, subentire, or lobed)
       7-1. Blades straight with the midnerve continuing the direction of the petiole.
          8-1. Nerves digitate Subkey 7-12
          8-2. Nerves pinnate
             15-1. Stem repent or scandent Subkey 14
             15-2. Stem erect Subkey 15-21
       7-2. Blades oblique or transverse with the midnerve making a distinct angle with the petiole
             22-1 Leaves “solitary” or fasciculate (may include some species with distinct internodes) Subkey 22-24
             22-2. Leaves separated by distinct internodes
                25-1. Stems repent or pendent
                   26-1. Staminate tepals 2 Subkey 25
                   26-2. Staminate tepals 3 or more, usually 4 Subkey 26
                25-2. Stems erect.
                   27-1. Inflorescence not dichotomously branched Subkey 27-28
                   27-2. Inflorescence dichotomously or more branched
                      29-1. Blades at least twice as long as wide Subkey 29-30
                      29-2. Blades less that twice as long as wide
                         31-1. Petioles vestite Subkey 31-32
                         31-2. Petioles glabrous or glabrescent Subkey 33-34


  1. All couplet numbers and subkey numbers correspond directly to those found in the Begoniaceae Main Key.
  2. Subkeys 1 and 13 have been omitted and the species put in other subkeys.
  3. Numerous species have been repositioned in the Key to clarifying some of the original "multiple entries" issues.
  4. Editors notes are included in parenthesis.
  5. For a listing of all pictured species, just click Alphabetical listing
  6. The notation for subkey references is as follows:

A special thanks to Jack Golding

We all owe thanks to Jack Golding, co-author of the Begoniaceae, Editions 1 an 2, for his helpful comments on this Pictorial Begonia Key.