Top 5 Poisonous Plant
In the mid-1800s, the story of a man-eating tree captured widespread attention. In a report he wrote for the South Australian Register, Carl Liche, a German explorer, claimed that while exploring Madagascar, he'd witnessed a woman climb the trunk of a large plant and drink its nectar. When the plant sensed her presence, it captured her with its tentacles and pulled her into its body.
One hundred years later, a 1950s science writer debunked the legend, asserting that not only was there no such tree, but that no one by name of Carl Liche had ever explored Madagascar.
While a tentacle-wielding, man-consuming tree may not exist, a scaled-down version of such a plant does. The man-eating tree of Madagascar may have been an exaggeration of the pitcher plants that grow in Madagascar, Indonesia, Australia, Malaysia and other hot and humid, low-lying areas. The largest of the pitcher plants is known as Nepenthes, and this plant does capture small vermin and lizards in its pitchers (or flowers).
The pitcher plant creates a substance within its leaves that coats the inside of its pitcher-shaped flowers. This substance mixes with water that the plant draws up through its roots. Insects and, on occasion, small animals are attracted to the scented water. When they come to drink, they fall into the pitcher, are unable to escape, and the plant draws nutrients from the captured prey.
While you certainly won't fall prey to the pitchers of the Nepenthes -- they're entirely too small to hold a human -- you could easily fall prey to the sickness some plants induce. In fact, the following five could actually kill you.
Rafflesia
" a penetrating smell more repulsive than any buffalo carcass in an advanced stage of decomposition" (Mjoberg, 1928) There are approximately 17 Rafflesia species distributed throughout Southeast Asia (Nais, 2000; Meijer, 1997; Mat Salleh, 1991). These species are highly specific as to the hosts that they parasitize, preferring only a few species of Tetrastigma (a member of the common grape family) that are distributed in the same geographic area. Although technically a member of the plant kingdom, Rafflesia challenges traditional definitions of what a plant is because they lack chlorophyll and are therefore incapable of photosynthesis (as are all members of its family, Rafflesiaceae).
While many parasites appear like normal plants, Rafflesia lacks any observable leaves, roots, or even stems (Meijer, 1993). Likened to fungi, Rafflesia individuals grow as thread-like strands of tissue completely embedded within and in intimate contact with surrounding host cells from which nutrients and water are obtained (Mat Salleh, 1996). Perhaps the only part of Rafflesia that is identifiable as distinctly plant-like are the flowers; however, even these are bizarre because they attain massive proportions (up to 3 ft in diameter) and are usually reddish-brown and stink of rotting flesh.. Although parasitic, Rafflesia species do not typically kill their hosts in spite of the drain on resources that they cause.
Pollination in Rafflesia has been studied (Beaman et al., 1988) but is likely a rare event due to the several factors. The flowers are unisexual and single sites usually produce either male or female flowers (see exception below). Therefore, in order to have effective pollination (reproduction), male flowers must be in close proximity to, and open at the same time as female flowers so that flies (or any other insect) can transfer pollen.
While male and female individuals could be closely spaced, flower bud mortality is 80-90 % per site thereby reducing the chance of co-flowering of two individuals (Nais, 2000). Furthermore, flower lifespan is only 5-7 days thereby placing a temporal bottleneck on the process of pollination (Beaman et al., 1988; Nais, 2000). To complicate matters further, current population distributions are fragmented due to habitat destruction. Thus, successful sexual reproduction relies on the unlikely event that a male and a female would bloom during the same 5-7 days and that a fly could carry pollen between the often widely separated populations.
Challenges to Studying Rafflesia
There are several reasons Rafflesia has remained difficult to study for the 180 years since its discovery. First, individuals grow entirely embedded within the body of the host plant that they parasitize (Kuijt, 1969). As such, Rafflesia individuals are only visible when they erupt from within the host body as a flower bud. Although traditional means of studying Rafflesia, like anatomical sectioning, could be performed, this method would likely result in death of both the host and parasite. Second, Rafflesia is rare in occurrence and can only be found in relatively remote lowland forests of Southeast Asia. In this region, much of its habitat has been converted to farm land or timber concessions and in some parts of its range, the buds are harvested and sold for their purported medicinal qualities. Third, even once Rafflesia individuals become visible as flowers, these only survive a few days before decomposing. All of these factors make it difficult to even find Rafflesia sites and even when they are known, the sites are often not protected so there is no guarantee that they will exist in subsequent years.
Unlike other parasites that are important to study due to the economic loss they cause to important crops, Rafflesia causes economic benefit through ecotourism: thousands of people go to Sabah (Malaysian, Borneo) annually hoping to see Rafflesia blooms (Nais & Wilcock, 1998).
For this reason, there is great interest in conserving Rafflesia sites rather than eradicating existing populations (as is the case for noxious parasitic plant weeds). Although preserving as much of its habitat as possible would be the simplest and most obvious way to conserve Rafflesia, this is not currently practical throughout its range. Therefore, there is a need to investigate key questions that will establish priorities for ex situ (not natural habitat) propagation (which is only recently possible for the first time in history [Nais & Wilcock, 1999]), management of currently protected sites and procurement of unprotected sites, and in situ (within natural habitat) breeding programs.
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