# Question #f26ac

Dec 30, 2017

Mistletoe and dodder are considered parasites because they get some or all of their nutrients from another living plant.

#### Explanation:

Plants are considered to be "parasitic" when they derive some or all of their nutritional requirements from another living plant.

All parasitic plants have modified roots, named haustoria (singular: haustorium).

$\text{The evolutionary event which gave rise to parasitism in plants}$
$\text{was the development of haustoria.}$
https://en.wikipedia.org/wiki/Parasitic_plant

The haustoria penetrate the host plant's conductive system – either the xylem, the phloem, or both – and extract water and nutrients from the host.
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Dodder attaches to the stems of its hosts.

You can see that the parasitic dodder plant has evolved to be without chlorophyll, so it has to be a parasite in order to live.
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Mistletoe attaches itself to the branches of trees.

You can see that mistletoe has chlorophyll, so it is photosynthetic to some degree.
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Here is a great web site to learn more about dodder, mistletoe (and the corpse plant too.) It has a couple of excellent videos, including a time-lapse video showing dodder from germination, to sinking its haustoria into the host plant, to completely covering the host,
https://owlcation.com/stem/What-Are-Plant-Parasites