Adaptations of Erythroxylum coca

Cocaine as an insecticide
One of Erythroxylum coca's adaptations was the evolution of cocaine in the leaves of the plant. Cocaine (C17H21NO4) is only one of the alkaloids synthesized within the plant. Some of the other alkaloids include benzoylecCocaine chemical formula. Used with courtesy from Wikimedia Commons.gonine, cuscohygrine, dihydrocuscohygrine, ecgonine, hydroxytropacocaine, hygrine, methrylecgonine cinnamate, tropacocaine, truxilline. While it is known that cocaine inhibits dopamine reuptake in mammals, it's natural function in the plant is still unknown. Recent studies show that cocaine in the leaves has been evolutionary selected to act as a sort of pesticide. In insects, cocaine acts as an inhibitor of the re-uptake of octopamine, an insect-specific neurotransmitter. Octopamine plays a similar role in insects as dopamine does in mammals, so insects that feed upon specific parts of plants from the Erythroxylum genus are likely to "overdose" on the octopamine in their nervous systems.

Nicotiana tabacum and Papaver somniferum are also plants that are cultivated for their naturally occurring alkaloids.


Another interesting adaptations of the coca plant, that sets it apart from other plants, is the evolution of its above-ground organ, the leaf. While the leaves do not resemble each other Coca leaves. Used with courtesy from the wide variety of coca, they are still distinguishable from other plants by having a slightly curved line on each side of the midrib. The lines run from the base to the apex and have the appearance of a rib, but in reality are a result of peculiar folding of the leaf while still in the bud. This "false" midrib is even more visible on the under face of the leaf, where it is darker in color due to the closer cellular structure.

The three most popular commercial varieties of coca leaves are "Huanuco coca" or Bolivian, "Truxillo coca" or Peruvian and "Java Leaf"
which is found in Indonesia.
The leaves of Huanuco coca (E. coca) range in color from clear brown to greenish brown wish a yellowish underside, smooth and slightly glossy, and having little or no petiole. The blades are four to eight centimeters in length and two to four centimeters in breadth, with a nearly elliptical shape. Veins and veinlets of the leaf are distinctly prominent, along with the line of collenchyma tissue that runs along either side of the reddish-brown midrib.
The leaves of Truxillo coca (E. truxillense) are pale green, brittle, thin, smooth but are without shine, shortly and stoutly petioled. The veinlets are much less marked and the two curved lines are much less distinct than that of Bolivian leaves. The midrib itself is green in color.
Java leaves are similar to the physical characteristics of it's South American cousins but only produce the intermediate precursors to cocaine and not cocaine itself.


Up close of a coca leaf. Picture taken by Robbin C. Moran.


One of the key characteristic features of the angiosperms, also known as flowering plants, is the flower. The flowers of the coca plant grow alone or in small groups on the junction of the branch and the leaf. They are usually off-white to ivory in color and are noted to emit a pleasant odor of almonds. The flowers themselves are considered to be perfect flowers, i.e. they contain both the male and the female reproductive organs grow on the same flower. The sepals, which are located immediately beneath the petals, occur in groups of five, along with the petals themselves which always occur in fives. The single female ovary in the plant is surrounded by ten male stamens, which have the sole function of ensuring fertilization and perpetuation of the species. Catharanthus roseus is another angiosperm which contains petals that occur in fives.




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