obligate parasite

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Parasitic broomrape

“Doting on Dodder”

obligate parasite

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July 1, 2026

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Parasitic broomrape — Parasitic broomrape Branched broomrape (Orobanche ramosa), also known as hemp broomrape. Frequently attacking agricultural crops, including tomatoes and tobacco, the plant is an obligate parasite and requires a host for its nutritional needs.

An obligate parasite is an organism that cannot complete its life cycle without exploiting a suitable host. These parasites are entirely dependent on their host for survival and reproduction, often lacking the ability to live independently in the environment. Many bacteria, such as Burkholderia mallei, Neisseria gonorrhoeae, Neisseria meningitidis, and Streptococcus pneumoniae, are obligate parasites. Viruses represent the ultimate form of parasitism, as they have no cellular structure and can only replicate within the host's cells, hijacking the host's cellular machinery for their own reproduction. This dependence means that obligate parasites are highly adapted to their specific hosts, and their existence is intrinsically linked to the host's well-being, though often at the host's expense.123

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bacteria
Nutritional requirements
Some bacteria are obligate parasites and grow only within a living host cell. Rickettsia and Chlamydia, for example, grow in eukaryotic cells, and Bdellovibrio grow in bacterial cells. Treponema pallidum is difficult, if not impossible, to grow in culture, probably because it requires low oxygen tension and low…
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Some bacteria are obligate parasites and grow only within a living host cell. Rickettsia and Chlamydia, for example, grow in eukaryotic cells, and Bdellovibrio grow in bacterial cells. Treponema pallidum is difficult, if not impossible, to grow in culture, probably because it requires low oxygen tension and low…
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disease
Host-parasite relationships
Most pathogenic bacteria are obligate parasites; that is, they are found only in association with their hosts. Some, such as staphylococci and streptococci, can proliferate outside the body of the host in nutritive materials infected from host sources. Within the tissues of the host, these organisms set up local…
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Most pathogenic bacteria are obligate parasites; that is, they are found only in association with their hosts. Some, such as staphylococci and streptococci, can proliferate outside the body of the host in nutritive materials infected from host sources. Within the tissues of the host, these organisms set up local…
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Doting on Dodder
Doting on Dodder transcript
They’re called obligate parasites, and they have completely lost the ability to make their own food. In short, they are the freeloaders of the botanical world. A few of these obligate parasites even take it a step further and live entirely within their hosts! These ones actually…
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They’re called obligate parasites, and they have completely lost the ability to make their own food. In short, they are the freeloaders of the botanical world. A few of these obligate parasites even take it a step further and live entirely within their hosts! These ones actually…
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fungus
Parasitism in plants and insects
…cell, are characteristically produced by obligate (i.e., invariably parasitic) parasites; some facultative (i.e., occasionally parasitic) parasites also produce them. Obligate parasites, which require living cytoplasm and have extremely specialized nutritional requirements, are exceptionally difficult, and often impossible, to grow in a culture dish in a laboratory. Examples of obligate parasites…
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…cell, are characteristically produced by obligate (i.e., invariably parasitic) parasites; some facultative (i.e., occasionally parasitic) parasites also produce them. Obligate parasites, which require living cytoplasm and have extremely specialized nutritional requirements, are exceptionally difficult, and often impossible, to grow in a culture dish in a laboratory. Examples of obligate parasites…
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Hydnora
Physical description and natural history
…of photosynthesis and are thus obligate parasites, meaning they are wholly dependent on their hosts for nutrition. The sprawling rhizomatous plants exist almost entirely underground and penetrate the roots of their hosts by means of haustoria.
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…of photosynthesis and are thus obligate parasites, meaning they are wholly dependent on their hosts for nutrition. The sprawling rhizomatous plants exist almost entirely underground and penetrate the roots of their hosts by means of haustoria.
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parasitic plant
Host dependence
Obligate parasites have an absolute requirement for a host, whereas facultative parasites can live and reproduce in the absence of a host. All holoparasites are, by definition, obligate. Even though hemiparasites are photosynthetically competent, some species nevertheless are obligate in terms of their reliance on…
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Obligate parasites have an absolute requirement for a host, whereas facultative parasites can live and reproduce in the absence of a host. All holoparasites are, by definition, obligate. Even though hemiparasites are photosynthetically competent, some species nevertheless are obligate in terms of their reliance on…
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microbiology
Viruses
All viruses are obligate parasites; that is, they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions. Once inside a cell, viruses have genes for usurping the cell’s energy-generating and protein-synthesizing systems.…
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All viruses are obligate parasites; that is, they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions. Once inside a cell, viruses have genes for usurping the cell’s energy-generating and protein-synthesizing systems.…
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