Cassytha

''Cassytha'' is a genus of some two dozen species of obligately parasitic vines in the family Lauraceae. Superficially, and in some aspects of their ecology, they closely resemble plants in the unrelated genus '' Cuscuta'', the dodders.Weber, J. Z. A TAXONOMIC REVISION OF CASSYTHA (LAURACEAE) IN AUSTRALIA. J. Adelaide Bot. Gard. 3(3): 187-262(1981
JSTOR
/ref> When fruit and flowers are absent in the field, the physical resemblance is so close that few people without technical training can discern the difference. In this respect and in their ecology the two genera present a spectacular example of convergent evolution.Nickrent, D. L. 2002. Phylogenetic Origins of Parasitic Plants. Chapter 3, pp. 29-56 In J. A. López-Sáez, P. Catalán and L. Sáez ds. Parasitic Plants of the Iberian Peninsula and Balearic Islands. Mundi-Prensa, Madrid. Nonetheless, Nickrent comments that "''Cassytha'' is uneqivocally assigned to Lauraceae based on (both) morphological and molecular data."The Parasitic Plant Connection: Phylogenetic Relationships of Parasitic Flowering Plants
/ref> In its divergence from habits typical of the Lauraceae, ''Cassytha'' also presents examples of mosaic evolution

Several species of ''Cassytha'' are regarded as pests in various regions, though as a rule they are not as serious a problem as the true dodders. Some even yield a welcome harvest of fruit, or are valued for their perceived medicinal or aphrodisiac properties, partly because, like many members of the Lauraceae, some are fragrant when bruised. Their stems make useful strings for construction of thatched roofs and certain styles of lei and the like.

Common names and confusion

Probably the most useful common names for ''Cassytha'' species are laurel dodder or dodder laurel, because they look like dodder and are fragrant members of the laurel family, Lauraceae. The name love vine has merit because some species, in particular ''C. filiformis'', are regarded as aphrodisiacs in the Caribbean region.Esbaugh, W. Hardy; McClure, Susan A. & Bolyard, Judith L. Bush Medicine Studies, Andros Island, Bahamas. Proceedings of the first symposium on the botany of the Bahamas 11–14 June 1985. Ed. Robert R. Smith., San Salvador, Bahamas.
In practice, the confusion between the various species of ''Cassytha'' and ''Cuscuta'' is so unavoidable that their common names are more or less interchangeable. Practically all the common names for dodder accordingly are widely applied in error to ''Cassytha'' as well, but as a matter of convenience in Florida at least, where members of both groups of plants are present as agricultural pests, a publication of the Department of Agriculture adopts the names woe vine for ''Cassytha'' and dodder for ''Cuscuta''.Haynes, Alan R., Coile, Nancy C., Schubert. Timothy S.; "Comparison of Two Parasitic Vines: Dodder (Cuscuta) and Woe Vine (Cassytha)". Botany Circular No. 30. Fla. Dept Agric. & Consumer Services January/February 1996. Division of Plant Industry

Context and distribution

Though the Lauraceae constitute a large family, with thousands of species in tens of genera, ''Cassytha'' is its only known parasitic genus, and its climbing habit also is atypical of the family; most Lauraceae are woody shrubs or trees. The genus at one time was assigned its own family, Cassythaceae, but currently agreement on its inclusion into the Lauraceae is general.

As currently defined, ''Cassytha'' has a wide distribution for a genus of so few species. Most are native to Australia (including temperate regions, where they are the only native members of the family), but a few are indigenous to Africa, southern Asia, various islands, and regions in the Americas. Some species seem to have been spread inadvertently by humans and probably by birds as well, and now occur on several continents. ''C. filiformis'', for example, grows in Hawaii (where it is said to be indigenous),Nelson, Scot C. "Cassytha filiformis". Plant Disease July 2008 PD-42 Department of Plant and Environmental Protection Sciences. Cooperative extension service. University of Hawaii at Manoa. www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-42.pdf the Australasian realm, northern South America, Central America, southern Florida, Japan, and South Africa.Arnold T.H., de Wet B.C. (Eds), Plants of Southern Africa: Names & Distribution, MEMOIRS OF THE BOTANICAL SURVEY OF SOUTH AFRICA No. 62, Pub.National Botanical Institute, South Africa.1993 It also appears to have been transported to many major islands, and now is effectively pantropical.

Botanical details

The genus is cited as ''Cassytha'' L., ''Sp. Pl.'' 35 (1753), which means that Carl Linnaeus formally described it in 1753 in his monumental work, ''Species Plantarum''. Otto Stapf updated the work in ''Flora Capensis'' in 1912.

''Cassytha'' is unusual among Lauraceae in at least two respects: they are scandent herbaceous plants, and they are obligate parasites. Their stems are thread-like or wiry, and like most twining species, they twine round the host clockwise as seen from the source of growth. The vines generally turn yellowish once they have established themselves on a productive host because they then reduce or stop their production of chlorophyll. ''Cassytha'' species are stem parasites, adhering to their hosts by uniseriate