Pteroxygonum

Pteroxygonum is a plant genus in the family Polygonaceae. As of March 2019, two species are recognized. Their native range is from Tibet to southeast China.[1]

Pteroxygonum
Pteroxygonum giraldii
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Order: Caryophyllales
Family: Polygonaceae
Subfamily: Polygonoideae
Genus: Pteroxygonum
Dammer & Diels[1]

Description

Species of Pteroxygonum are twining vines growing from a large woody globe-shaped tuber. Their leaves are broad and palmate, with a dark red mark around each primary leaf vein. The inflorescence is in the form of an axillary raceme. The flowers are bisexual, with five spirally arranged tepals, eight stamens joined at the base, and three styles, also joined up to about the middle. Nectar is produced from tissue at the base of the staments. Their fruits are in the form of winged, three-angled achenes.[2]

Taxonomy

The genus Pteroxygonum was erected in 1905 by Carl Dammer and F. Ludwig Diels for the species Pteroxygonum giraldii. They separated Pteroxygonum from Polygonum on the basis of the "very notably different structure of the fruit".[3] Until 2015, the genus was considered to contain only this species. A 2015 molecular phylogenetic study found that the species formerly called Polygonum denticulatum was closely related to Pteroxygonum giraldii, and accordingly moved it to Pteroxygonum.[2]

Pteroxygonum is placed in the subfamily Polygonoideae, tribe Pteroxygoneae. Some species assigned to the genus Fallopia were placed alongside Pteroxygonum in the cladogram resulting from the 2015 study, and may belong to a new genus.[2]

Polygonoideae
 

Oxygoneae

 
 
 

Persicarieae

 
 
 

Fagopyreae

 
 
 

Pteroxygoneae (Pteroxygonum + some Fallopia)

 
 
 

Calligoneae

 
 
 

Rumiceae

 
 

Polygoneae

 
 
 
 
 
 
 

Species

As of March 2019, Plants of the World Online accepted two species:[1]

References
  1. "Pteroxygonum Dammer & Diels". Plants of the World Online. Royal Botanic Gardens, Kew. Retrieved 2019-03-01.
  2. Schuster, Tanja M.; Reveal, James L.; Bayly, Michael J. & Kron, Kathleen A. (2015). "An updated molecular phylogeny of Polygonoideae (Polygonaceae): Relationships of Oxygonum, Pteroxygonum, and Rumex, and a new circumscription of Koenigia". Taxon. 64 (6): 1188–1208. doi:10.12705/646.5.
  3. Diels, L. (1905). "Pteroxygonum Dammer et Diehls n. gen.". Beiblatt zu den Botanischen Jahrbüchern (in German and Latin). 36. p. 36. Retrieved 2019-03-10. fructus structura valde insigni diversum

Bibliography
  • "Reappraisal of the generic status of Pteroxygonum (Polygonaceae) on the basis of morphology, anatomy and nrDNA ITS sequence analysis", Wei SUN et al., Journal of Systematics and Evolution 46 (1): 73–79 (2008).
  • eFloras description
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