Systematics/Phytogeography / Taxonomie/ Section
Costea, Mihai , Stefanovic, Sasa .
Demanding equal rights for parasitic plants: systematics and conservation of Cuscuta jepsonii (Convolvulaceae), a Californian species presumed to be extinct.
Although numerous studies on the ecology of different parasitic plants have clearly shown that they act as keystone species and ecosystem engineers, their conservation is fraught with more challenges than autotrophic plants. These challenges stem from the overall negative image parasitic plants have received, especially in the groups that include some invasive or weedy species. The most successful parasitic plants are “the generalists”, capable of parasitizing a wide variety of hosts from different families. In contrast, “the specialists” are restricted to one or few host genera/species. Our observations on Cuscuta (dodders, Convolvulaceae) suggest not only that species from this latter category are extremely vulnerable and that the narrow host specialization is a good predictor of conservation problems, but also that “specialist” dodders are likely to develop conservation issues or even to become extinct before their hosts. Cuscuta jepsonii (Jepson’s dodder) represents such an example. This species is endemic to California and it is currently presumed extinct. Because it has been known only from the holotype, its phylogenetic affinities, morphologic variation, and ecology have remained unknown or at the stage of supposition. While examining Californian herbarium material for the treatment of Cuscuta in the Jepson Manual we have recently found additional specimens that allowed us to confidently place it in the Cuscuta californica clade, and not in the lineage of Cuscuta indecora as was recently proposed. Taking into account the phylogeny and the ecology of the only two known host species, Ceanothus prostratus and C. diversifolius (California lilacs, Rhamnaceae), we hypothesize that Cuscuta jepsonii may also parasitize other more or less prostrate species of Ceanothus with a similar ecology (e.g. Ceanothus pumilus, C. arcuatus, C. fresnensis), and we suggest that there are some chances Jepson’s dodder may be rediscovered in the future.
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Digital Atlas of Cuscuta (Convolvulaceae)
1 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
2 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, July 30th, 2008
Time: 1:00 PM