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 II system of 2003 (unchanged from the APG system of 1998) uses the following circumscription:
The AP-Website indicates that Balanophoraceae should also be included in this order (post APG II). It also indicates that Olacaceae (sensu APG II) is not a good family and should be split. Furthermore, it indicates doubt about Santalaceae. Studies based on DNA sequences also indicate that the family Schoepfiaceae should be resurrected to accommodate Schoepfia (formerly in Olacaceae), Arjona and Quinchamalium (both previously in Santalaceae).
The Cronquist system (1981) used the following circumscription:
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 the former within the family Peridiscaceae of the order Saxifragales, and the latter within the order Malpighiales close to Passifloraceae-Turneraceae-Malesherbiaceae. 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.
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