a bit of botany : 4 / inflorescence and flowers

 

Instead of looking all botanical characters of inflorescences and flowers of genus Begonia plants, I think it would be sensible and less tedious to describe in detail some typical infloresecnces of this very large genus ; specific vocabulary will be explained in this first page and illustrated with photos.

 

Two important notes :

 

 

In Begonia genus :

  • flowers features are of taxonomic interest for Begonia classification and identification
  • staminate flowers and pistillate flowers are always distinct.  

Vocabulary

inflorescence :

  • axillary inflorescence : inflorescence which starts from a leaf insertion.
  • monochasial inflorescence : an inflorescence is monochasial if all axes end by only a flower.
  • dichasial inflorescence : an inflorescence is dichasial if each axis is divided into two opposite axes.
  • raceme : an inflorescence is a raceme if the pedicels of flowers are fixed at differents levels on the peduncle, the older at the base.
  • paucifloral inflorescence : inflorescence with few flowers.                               
  • bisexual inflorescence : one inflorescence which has staminate flowers and pistillate flowers.
  • unisexual inflorescence : an inflorescence which has staminate flowers or pistillate flowers.
  • dioecious plant : staminate flowers and pistillate flowers are on different plants.
  • monoecious plant : on a plant we see staminate flowers and pistillate flowers
  • bract : a more or less modified leaf subtending an axis ; it protects the inflorescence before opening.
  • bracteole : small bract on a pedicel of a pistillate flower, between bracts and flower.






 

flowers :

  • pedicels : axes which bear each flower.
  • peduncle : the axis which bears the inflorescence.
  • segments : in genus Begonia it is difficult to distinguish sepals and petals ; however, they are different ; so, it is better to use the word segments  (rather than tepals which makes us think they are identical) ; there are outer segments and inner ones, according to their tendril.
  • perianth : the whole of segments of a flower.
  • sessile : a flower without peduncle or pedicel.
  • protandrous : inflorescence which staminate flowers shed pollen before pistillate flowers are receptive
  • protogyne : inflorescence which pistillate flowers are receptive before stamens shed pollen.

 



 

staminate flower : stamen / anther / pollinic bag / filament / connective : a stamen is an organ of the mâle flower where the pollen is produced ; it is made up of anther which contains pollinic bags where is the pollen and of the filament which bears anther ; the tissue which connects pollinic bags is connective.

  • androecium : the whole of stamens.
  • actinomorphic : when the androecium is actinomorphic it presents a radial symmetry (symmetry with respect to a vertical axis)
  • zygomorphic : when the androe­cium is zygomorphic all stamens are generally positioned in the same direction, resembling a bunch of bananas (symmetry with respect to a vertical plan)

 

 

 

pistillate flower :

  • pistil : the whole of female elements of a (pistillate) flower : it is made up of ovary and styles which bear stigmas.
  • stigmas : the apical part of the pistil which fixs the pollen
  • styles : part of the ovary which bears stigmas.
  • ovary / locules / ovules : the ovary is the hollow part of the pistil which is made up of several locules which contains ovules.
  • placenta : wall ovary thickening which bears ovules (the placenta form and the ovules position are very varied).
  • wings : outer ovary appendages more or less spread out.

 

divers

  • apex : extremity.
  • apical : which is at the extremity or at the top.
  • lancolate : spear-shaped, elongated and sharp, the less wide part at the base.
  • oblanceolate : lanceolate, the wider part at the top.
  • oblong : more longer than wide.
  • obovate : egg-shaped, the more narrow part at the base.
  • déhiscence : anther or fruit opening ; the opening way of these organs.
  • serrate : with small, sharp and oblique teeth to the margin, as a saw.

    Bibliographie :

        • Studies in Begoniaceae VII / J.JF.E. de Wilde (Wageningen Agricultural University1998 / The Netherlands)
        • The sections of Begonia / J. Doorenbos – M.S.M. Sosef – J.J.F.E/ de Wilde (Backhuys Publishers 2002)
        • Dictionnaire illustré de Botanique / A. Jouy – B. de Foucault (Biotope Editions 2016)

     

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