Androecium structure

D. A. (2004). Comparative floral development and androecium structure in Malvoideae (Malvaceae... 

Androecium - The androecium consists of at least six structures that are interpreted as nectariferous, and three stamens or staminodes of which only the fila-ments/filament bases are preserved. The nectariferous structures are arranged in pairs and each pair is associated with a more centrally placed filament/filament... 

Androecial characters such as presence and position of staminal appendages, as well as number of sporangia are highly variable among extant Lauraceae and may also vary within genera. This relative flexibility in the structure of the androecium... 

The presence of a basally united perianth composed of two distinct perianth whorls, and an androecium with at least one whorl of stamens associated with stalked, presumably nectariferous, structures in Powhatania connata indicates a relationship to extant Laiuales. The stalked structures are distinctive in their shape and position. They are free with semi-peltate/peltate heads and occur in a lateral position to the stamens of the first androecial whorl. 

In this chapter the floral development of two species of Napoleonaea is investigated to understand the structure of the androecium and to clarify the controversy about the presence of apetaly in the family. 

It is demonstrated that the corona represents a complex structure, which is part corolla and part androecium, represented by two series of distinct staminodes. The argument that the flower is apetalous because of the strong resemblance and association of outer petaloid appendages to the stamen tube gains little support because of the initiation of petal lobes before the androecium and from the fact that petals and stamens are connected by a common stamen-petal tube, which is widespread in asterids. A floral developmental study of genera of Scytopetaloideae, Crateranthus and Astemnthos is expected to confirm the earlier initiation of the outer corolla before the centrifugal development of the androecium. 

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