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To structure our study, we analyzed the possible evo-lutionary history of staminodes in the context of the Chase et al. (1993) phylogeny of the angiosperms, which was inferred from the DNA sequence of most of the chloroplast rbcL gene.
In botany, a staminode is an often rudimentary, sterile or abortive stamen, which means that it does not produce pollen. [1] [page needed] Staminodes are frequently inconspicuous and stamen-like, usually occurring at the inner whorl of the flower, but are also sometimes long enough to protrude from the corolla. [citation needed]
1 paź 2000 · When a pollinator probing for nectar touches the staminodes, the style is released and contacts the pollinator. Following style contact, the anthers of the two fertile stamens explode and dust the pollinator with pollen.
This article aims to discuss the shortcomings of the past and current approach of staminodes and proposes definitions of staminode types for use as characters in phylogenetic analyses. Staminodial structures should be classified according to their position and function in the flower.
Stamens initiate as primordia from the flower apical meristem, but at maturity are attached to the receptacle, corolla (having an epipetalous stamen fusion; see below), hypanthium rim, or staminal disk, a fleshy, elevated, often nectariferous cushion of tissue.
The phylogenetic distribution of staminodes suggests that they typically arise during evolutionary reduction of the androecium. Differences in the genetic control and patterns of stamen loss between actinomorphic and zygomorphic flowers shape staminode development.
The trends in the reductive process of stamens (staminode origin) are understood as a semophyletic sequence that can still be traced in certain groups of plants. A reduction in size of stamens, correlated with a retardation of initiation of primordia, can be seen as a first obvious step in the process (Fig. 54).
