On the Submersion of Dicraurus into Iresine (Amaranthaceae)

Abstract

The two species of Dicraurus Hook. f. (Amaranthaceae) are shown to be more closely related to different species in Iresine L. than they are to one another. In addition, characters used to distinguish Dicraurus are more widespread within Iresine than was formerly thought, necessitating the merger of Dicraurus into Iresine. The two species as placed in Iresine are I. alternifolia S. Wats. and I. leptociada (Hook. f.) Henrickson & Sundberg. Complete descriptions and distribution maps of the two species are included.

Pollen types in the Amaranthaceae. Morphology and evolutionary significance

“…Taxonomic concepts of genera follow those accepted by Townsend (1993), apart from Hebanthe (sensu Borsch & Pedersen 1997), Iresine (incl. Dicaurus, sensu Henrickson &Sundberg 1986, andexcl. Trommsdorffia, sensu Borsch, 1995), Omegandra (sensu Leach et al 1993), Pfaffia (incl.…”

Pollen characters and DNA sequence data converge on a monophyletic genus Iresine (Amaranthaceae, Caryophyllales) and help to elucidate its species diversity

“…Sublineage A1 includes the former genus Dicaurus, here represented by I. alternifolia. Dicaurus was submerged into Iresine by Henrickson & Sundberg (1986) despite its deviating alternate leaves because of compelling similarity in floral morphology with other species of Iresine.…”

“…Our trees indicate the alternate leaf orientation must be derived in Iresine, considering that I. alternifolia is deeply nested within the Iresine clade that otherwise only has species with opposite leaves. Although the position of I. alternifolia is not fully resolved, this species with a distribution in the Sonoran Desert region in Sonora, south-central Baja California and on several islands in the Gulf of California (Henrickson & Sundberg, 1986;Zumaya, unpubl. data) clearly belongs to sublineage A1, which also contains other species of the northern dry regions of Mexico such as I. hartmanii Uline. Further molecular data are needed to clarify these relationships.…”

“…1B, E). A variety of trichome types occurs, such as appressed dolabrifom (I. leptoclada), branched with one arm long and the others short, secondarily branched (I. schaffneri S.Watson) with side-branches variously crinkled, or simple peltate-stellate (I. pringlei S. Watson;Henrickson & Sundberg, 1986). A unique type of uniseriate yellow trichomes with tough walls occurs in Irenella (Eliasson, 1987(Eliasson, , 1988 but this can also be understood as derived from the variable set of ancestral trichome characters within the Iresine clade.…”