Sympetalae


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Sympetalae

 

a subclass of angiospermous dicotyledonous plants that includes families whose representatives are characterized by united petals. The petals may be united partially (only at the base or up to the middle of the petals) or completely.

In most Sympetalae the concresced basal part of the petals forms a tubule, and the upper parts resemble lobes, segments, or denticles. Also characteristic are a gamosepalous calyx, a cyclical flower, and one ovular covering (and not two, as in most polypet-alous plants). The staminal filaments and the floral tubule con-cresce over a more or less considerable surface.

The classification of the Sympetalae as a separate group (opposed to the Choripetalae) was proposed in 1864 by the German botanist A. Braun. In 1892 the German botanist A. Engler proposed the term “Metachlamydeae” for the Sympetalae because he considered the Sympetalae to be more highly organized than the Choripetalae and the Archichlamydeae. Most modern phylogenetic systems do not distinguish the Sympetalae as a separate subclass of dicotyledons.

M. E. KIRPICHNIKOV

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This group has been recognized by botanists since the eighteenth century, receiving names such as the Monopetalae, Gamopetalae or Sympetalae (Wagenitz, 1992) all of which allude to the characteristic connate corolla.
A podium is therefore an insignificant structure, present in many plants with an insignificant nucellus, such as in Euphorbiaceae and many tenuinucellate Sympetalae (Dahlgren, 1940; Bor & Kapil, 1975).
Excluded Families: The Rubiaceae (Schumann, 1891) was placed in the Rubiales under the Sympetalae.