Inflorescence - General Characteristics - Metatopy

Metatopy

Metatopy is the placement of organs out of their normally expected position: typically metatopy occurs in inflorescences when unequal growth rates alter different areas of the axis and the organs attached to the axis.

When a single or a cluster of flower(s) is located at the axil of a bract, the location of the bract in relation to the stem holding the flower(s) is indicated by the use of different terms and may be a useful diagnostic indicator.

Typical placement of bracts include:

  • Some plants have bracts that subtend the inflorescence, where the flowers are on branched stalks; the bracts are not connected to the stalks holding the flowers, but are adnate or attached to the main stem (Adnate describes the fusing together of different unrelated parts. When the parts fused together are the same, they are connately joined.)
  • Other plants have the bracts subtend the pedicel or peduncle of single flowers.

Metatopic placement of bracts include:

  • When the bract is attached to the stem holding the flower (the pedicel or peduncle), it is said to be recaulescent; sometimes these bracts or bracteoles are highly modified and appear to be appendages of the flower calyx. Recaulescences is the fusion of the subtending leaf with the stem holding the bud or the bud itself, thus the leaf or bract is adnate to the stem of flower.
  • When the formation of the bud is shifted up the stem distinctly above the subtending leaf, it is described as concaulescent.
  • Flower and subtending bract

  • Lilium martagon (flower and subtending bract)

  • Concaulescence

  • Solanum lycopersicum (concaulescence)

  • Recaulescence

  • Tilia cordata (recaulescence)

Read more about this topic:  Inflorescence, General Characteristics