parasitic plants

ATo live at the expense of others is considered improper among people, and social orders that make such things necessary, favor them or even just make them possible are the anathema of every modern-minded social theory. Biology sees it more loosely. More than forty percent of all known species of organisms are parasites. They exist by affecting the health or at least the well-being of the fellow creatures they infest. And among them there are not only tapeworms or mosquitoes – there are also parasitic plants.

Ulf von Rauchhaupt

Editor in the “Science” section of the Frankfurter Allgemeine Sunday newspaper.

In this country, mistletoe immediately came to mind. But it is only a semi-parasite that taps into the sap of its host tree, but still has its own foliage to use in the sunlight. However, there are also total plant parasites that completely steal energy and material from their host. In our latitudes, for example, the large broomrape (Orobanche elatior) in addition, a plant from the order of the mint family, which is yellowish on the stem and otherwise not particularly attractive, which parasitizes on certain meadow flowers.

1.11 meter flower diameter: A Rafflesia in West Sumatra

1.11 meter flower diameter: A Rafflesia in West Sumatra

Image: AFP

There is even a whole family of parasitic plants, the Rafflesiaceae, which thrive in Southeast Asian rainforests. They are all large sessile red flowers dotted with light speckles with a rubbery feel and murderous stench, which is why they are also called corpse flowers. Among them, it brings the flowering of those native to Sumatra and Borneo Rafflesia arnoldii up to one meter in diameter and ten kilograms in mass, making it the largest flower on the planet.

Mimicking rotting flesh to attract scavenging pollinators is all a Rafflesiacea does. These plants have no roots or leaves, consisting only of their monstrous flowers and meter-long filaments that weave through the tissues of the vines they infest. In 2014, the botanist Jeanmaire Molina examined the genome of the Philippine Rafflesia lagascae. As she found out, the plant had not only lost the ability to photosynthesize, but also the genes for the formation of plastids, cell organelles that include the chloroplasts, which are important for photosynthesis. This Rafflesia is therefore even less of a plant than the malaria pathogen Plasmodium falciparumwhich still has its plastid genes, although its last photosynthetic ancestor, a red alga, lived hundreds of millions of years ago.

From the Rafflesia genome Sapria himalayan even half of all genes that occur in almost all plant strains have disappeared – nevertheless it is as extensive as that of humans. One of the reasons for this is that this parasite not only steals nutrients from its hosts. Its genome contains a vast collection of stolen DNA, from which Molina unearthed genes from long-extinct plants, right down to a mid-Cretaceous mock vine believed to be an ancestor of the sappira had infested. But the question is how long the Southeast Asian corpse flowers will continue to accumulate foreign DNA. Their habitat is severely threatened by the overexploitation of the rainforest in their homeland. To aid in Rafflesia research and conservation efforts, Molina now wants to try cultivating them at the Botanical Gardens in Washington, DC. Comments from pranksters critical of capitalism that this city is particularly good breeding ground for parasites shouldn’t be long in coming.

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