Viscum.dk
Parasitic plants
 

CONTENTS:



About Viscum
(Mistletoes)


Curriculum vitae (C.V.)


Green fingers

Plant lifeforms

Publications


Hemi- and holoparasitic families of flowering plants

Hemiparasites
(with chlorophyll - dependent on water and mineral nutrients from host):


Olacaceae 14/14/ca 100
Schoepfiaceae 1/1/30
Opiliaceae 10/10/ca 30
Loranthaceae 73/73/ca 910
Misodendraceae 1/1/8-10
Eremolepidaceae 3/3/11
Santalaceae 35/35/ca 430
Viscaceae 7/7/ca 600
Krameriaceae 1/1/17
Lauraceae (Cassytha) 50/1/16
Convolvulaceae (Cuscuta) 57/1/ca 145
Orobanchaceae 105/88/ca 1800

Holoparasites
(no chlorophyll - all water, organic and inorganic nutrients supplied from host):


Orobanchaceae 17/17/ca.270
Cynomoriaceae 1/1/2
Lennoaceae 2/2/5
Apodanthaceae 3/3/23
Cytinaceae 2/2/7
Mitrastemonaceae 1/1/2
Raffleciaceae 3/3/20
Hydnoraceae 2/2/15-18
Balanophoraceae 17/17/44-45

Code:
total number of genera/number of parasitic genera/total number of species

Hemiparasites: ca 4100 species. Holoparasites: 390 species. Parasites: ca 4500 species
--


Pedicularis flammea, Disko - a hemi-parasite

Comments to the table:
Cuscuta (dodder) is sometimes classified in a separate family, Cuscutaceae, with only one genus, Cuscuta. If so, only Lauraceae includes both non-parasitic genera (autophytes) and parasitic ones. The hemiparasitic subfamilies Rinanthoidea and Buchneoidea (Scrophulariaceae) is now transferred to Orobanchaceae. The three small holoparasitic families Apodanthaceae, Cytinaceae, and Mitrastemonaceae were earlier included in Rafflesiaceae. See also the overview of parasitic families in relation to types of parasitism.

Definitions:
Parasitism occurs, when one plant exploit another and by doing so causes damage to the first one (the host).

Through a structural-physiological bridge (the haustorium) parasitic plants absorb water and nutrients from one or more host plants. However, some other plants acts similarly but here the bridge is the mycelium of a mycorrhiza forming fungus. Such plants involved in a relationship of at least three species are now called myco-heterotrophic plants. Many, if not most, of the plants known as saprophytes seem to be myco-heterotrophic.

Obligate parasites cannot live without a host but facultative parasites (examples only to be found among hemi-parasites and so far only demonstrated under laboratory conditions) may survive without a host but in a far less vigorous condition.

Literature:
The numbers 10, 13, 16-19, 25, and 29 of the Publication list deal with parasites. The numbers 53-56 are in Danish but rich in nice colour illustrations. No. 60 about Nordic parasitic plants are in Dansih but with Figure legends in English.
See also 'About Viscum' and 'Growing Viscum' (mistletoe).
The classical scientific book on parasites is: J. Kuijt, 1969: The Biology of Parasitic Flowering Plants.
There are plenty of colour photographs in H S Heide-Jørgensen 2008: Parasitic flowering plants.
There are plenty of entries on the WEB dealing with parasitic plants, and the most comprehensive is:
http://www.science.siu.edu/parasitic-plants/
--------------------------------------------------------------
H. S. Heide-Jørgensen, November, 2008