What makes a plant a PARASITIC plant?

- Parasitic plants are defined as vascular plants which have developed specialized organs that penetrate the tissues of other vascular plants (hosts).They establish connections to the vascular tissue of the host in order for the parasite to absorb the host's nutrients.

- Despite their wide diversity, parasitic plants, like normal plants, have a basic body structure. Like other plants, they have a shoot system and a root system, but what sets parasitic plants apart is that the root meristem can develop a whole new organ: the haustorium.
* Upon contact with a host, a part of the parasite's root will actually develop its attachment organ, the haustorium.
* The haustorium consists of a host attachment structure, a heavily vascularized infection peg, and thin filaments that infiltrate the host vascular bundles.
* The filaments that invade the host can enter the xylem, the phloem, or even both.

- In order to successfully invade a host, a parasitic plant must be able to read and respond to the host's cells. By doing so, the host plant is unaware of its attacker and allows the parasitic plant into its "developmental social circle."

- Along with the nutrients gained by the host plant, some parasitic plants still gather their own nutrients and use photosynthesis for energy.

As in most things, there is a wide variety amongst parasitic plants, and not all of them act in the way just described. Here is a list of the 6 basic ways to characterize a parasitic plant:

1. Obligate parasite - a parasite that cannot complete its life cycle without a host.
2. Facultative parasite - a parasite that can complete its life cycle independent of a host.
3. Stem parasite - a parasite that attaches to the host stem.
4. Root parasite - a parasite that attaches to the host root.
5. Holoparasite - a plant that is completely parasitic on other plants and has virtually no chlorophyll.
6. Hemiparasite - a plant that is parasitic under natural conditions and is also photosynthetic to some degree. Hemiparasites may just obtain water and mineral nutrients from the host plant. Many obtain at least part of their organic nutrients from the host as well.

(Nuytsia floribunda, seen above, is an obligate root hemiparasite)