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Posted on March 28th, 2013, by

Parts of a simple flower have very distinct functions that can be traced without any reference to adaptation, but some flowers may lack some functions or they may be performed by different organs. In this case, an organ morphologically differs from its normal state; it includes some adaptations to a new function. In this paper, we will focus on the structural modifications of Amorphophallus titanum, which, besides, has the largest inflorescence that reaches a height of 3 m.

Its inflorescence is a yellow cob wrapped by a phylloid appendage and convolute spathe with dark burgundy red inner and green outer surface. Its blooming lasts two days only. The underground part of the plant is a giant tuber up to 50 kg. The flower’s smell resembles a blend of smells of rotten eggs and rotten fish, and in appearance resembles a decaying piece of meat. Flowering occurs as if suddenly a pedicel appears out of the ground and the flower blossoms with no shoots or leaves; its only leaf is released later (Bown, 2000).

The spadix includes several areas performing different functions in the pollination. The uppermost part of the spadix is dark cherry, a little extended, with no flowers. It is called sterile appendage and used for emitting odorous compounds that attract pollinators. Below are the elastic bristles providing an easy access to the lower chamber of the inflorescence, but blocking the way out. They are used for keeping the insects in the lower chamber. And finally, at the spadix bottom are staminate (up to 5000), and pistillate flowers involved in pollination (Bown, 2000).

While blooming after midnight the sterile appendage warms up to about 40°C and the scent accompanied by an unbearable stench is emitted in the air attracting dung beetles for pollination. They penetrate into the lower chamber and cannot get out of the bristles, thus spending the rest of the night and all day in the chamber with immature stamens and pistils. Early in the evening the lower chamber warms up stimulating the insects and pollen ripening. It falls on insects, and they bring it to pistillate flowers. Once pollination has occurred, bristles fade and by midnight the insects are free to again climb into an unpollinated inflorescence bringing the pollen of the previous plant.

When the process is completed, the mantle shrinks and falls off, as well as the top of the spadix, leaving only the part, on which female flowers give off the red berries. And only when the berries are formed, the plant produces a leaf. This lepidoid leaf can reach the height of about 2-3 meters, and is sometime called a snake palm (Bown, 2000).

All these adaptations have both positive and negative aspects: they promote visits of some insects and eliminate visits of others. The general direction of the evolution of pollination is a growing improvement, combining the flower and pollinator by increasingly close ties. This benefits each party, but close interdependence, according to Baker and Hurd (Baker, Hurd, 1968), also presents a potential weakness. If one of the partners disappears, the other also perishes unless it develops a compensatory mechanism. Resettlement of any one partner in the new areas depends on the resettlement of the other; and the species with the most non-specialized system of mating, including pollination, are adapted most successfully (Baker Law).

References
Baker, H. G., & Hurd, P. D., Jr. (1968). Intrafloral ecology. Annual Review of Entomology, 13, pp.385-414.
Bown, D. (2000). Aroids: Plants of the Arum Family. Timber Press.

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