Santalales

Santalales
Santalum haleakalae
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Core eudicots
Order:	Santalales
Families
See text

Santalales is an order of flowering plants with a cosmopolitan distribution, but heavily concentrated in tropical and subtropical regions.

Most have seeds without a testa, which is unusual for flowering plants. Many of the members of the order are parasitic plants, mostly hemi-parasites, able to produce sugars through photosynthesis, but tapping the stems or roots of other plants to obtain water and minerals; some (e.g. Arceuthobium) are obligate parasites, have low concentrations of chlorophyll within their shoots (1/5 to 1/10 of that found in their host’s foliage) and derive the majority of their sustenance from the host’s vascular tissues (water, micro- and macro-nutrients, and sucrose). Mistletoe is the common name for a number of parasitic plants within the order Santalales.

The APG III system of 2009 (slightly changed from the APG II system of 2003 and the APG system of 1998) uses the following circumscription:

• order Santalales

• family Balanophoraceae
• family Loranthaceae
• family Misodendraceae
• family Olacaceae
• family Opiliaceae
• family Santalaceae
• family Schoepfiaceae

The AP-Website indicates that Olacaceae (sensu APG II) is not a good family and should be split. Furthermore, it indicates disagreements about Santalaceae which needs to include Viscaceae to be monophyletic (as is done in APG III). Studies based on DNA sequences also indicate that the family Schoepfiaceae should be resurrected (as has been done in the updated APG III-publication) to accommodate Schoepfia (formerly in Olacaceae), Arjona and Quinchamalium (both previously in Santalaceae).

The Cronquist system (1981) used the following circumscription:

• order Santalales

• family Medusandraceae
• family Dipentodontaceae
• family Olacaceae
• family Opiliaceae
• family Santalaceae
• family Misodendraceae
• family Loranthaceae
• family Viscaceae
• family Eremolepidaceae
• family Balanophoraceae

The families Viscaceae and Eremolepidaceae are included in the family Santalaceae by the APG. The genera Dipentodon (Dipentodontaceae) and Medusandra (family Medusandraceae) are regarded as unplaced by APG II (as is the family Balanophoraceae, now likely to be reincluded; see above). The family Medusandraceae consisted of two genera: Soyauxia and Medusandra. Molecular evidence place them within the family Peridiscaceae of the order Saxifragales. The Chinese monotypic genus Dipentodon is close to Tapiscia and is proposed to constitute the new order Huerteales with Tapisciaceae and the genus Perrottetia formerly placed in the family Celastraceae.

References

• Hawksworth, FG (1996). Dwarf mistletoes : biology, pathology, and systematics. USDA For. Serv. Agric. Handb. pp. 409. 
• Soltis, PS; PK Endress, MW Chase, DE Soltis (ed) (2005-06-15). Phylogeny & Evolution of Angiosperms. Sinauer Associates. pp. 370. ISBN 978-0878938179. 
• Santalales on the Parasitic Plant Connection web page
• NCBI Taxonomy Browser