PARASITES, THEIR RELATIONSHIPS AND THE DISINTEGRATION OF SCROPHULARIACEAE SENSU LATO

Abstract

Plants that parasitise other plants have been among the most difficult plant groups to fit into classification systems due to their modified biology and their often highly reduced morphology. They are now considered to be found in about 16 families of flowering plants. Here we summarise current ideas about their relationships and provide information about their characteristics and utilisation. A major consequence of the revised classification of Orobanchaceae and related families has been the break-up of the traditional Scrophulariaceae, and here we summarise the new classification, focusing on genera of horticultural interest.

Results from an online survey of family delimitation in angiosperms and ferns: recommendations to the Angiosperm Phylogeny Group for thorny problems in plant classification

“…It took much effort by workers such as Barlow, Wiens, Kuijt and others to demonstrate how these groups were separate, so to ‘go backward’ and lump into Santalaceae adds to the confusion and results in no scientific advancement. That there is still confusion about these plants was demonstrated by a recent publication (Fay et al ., ) that placed Phoradendron in Loranthaceae and erroneously said that APG lumped Viscaceae into Loranthaceae. [N.B.…”

“…It is here that we must confront the biggest problems posed by molecular studies, indicating that we have what are apparently sets of genera forming what should be families in orders, but for which characters are for the most part lacking. A good example of this problem is the recently recognized angiosperm order Huerteales (Worberg et al, 2009;Christenhusz et al, 2010). No classification has ever conceived that there might be such an association of genera, and no-one can suggest characters that might be used to recognize this order.…”

SEED GERMINATION AND PLANT DEVELOPMENT IN Escobedia grandiflora (OROBANCHACEAE): EVIDENCE OF OBLIGATE HEMIPARASITISM?

“…Facultative hemiparasites can survive in autotrophic form, independent of the host, for at least part or all of their life cycle. They can reproduce without a connection to a host, and when available, parasitize opportunistically on neighboring plants (Fay et al, 2010;Westwood et al, 2010). In contrast, obligate parasites must parasitize a host in order to complete their life cycle (Westwood et al, 2010).…”

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“…Scrophulariaceae and their relatives in Lamiales have undergone major reorganisation in recent years (Tank et al ., , and references therein) and the changes have been summarised by Fay et al . () and others, but not all of these changes are reflected here. For example, Scrophulariaceae as used in this volume include taxa that are recognised in the APG system as being members of Orobanchaceae ( Melampyrum and other chlorophyllous root parasites), Phrymaceae ( Mimulus ) and Plantaginaceae ( Antirrhinum , Digitalis , Veronica etc.)…”