Trochodendron nastae
| Trochodendron nastae Temporal range:Ypresian
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|---|---|
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| Trochodendron nastaespecimen | |
Scientific classification
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Order: | Trochodendrales |
| Family: | Trochodendraceae |
| Genus: | Trochodendron |
| Species: | †T. nastae
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| Binomial name | |
| †Trochodendron nastae Pigg,Wehr,& Ickert-Bond, 2001
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Trochodendron nastaeis anextinctspecies offlowering plantin the familyTrochodendraceaeknown fromfossilleaves found in the earlyEoceneYpresianstageKlondike Mountain Formationdeposits of northernWashington state.T. nastaeis one of the oldest members of the genusTrochodendron,which includes the living speciesT. aralioides,native toJapan,southernKoreaandTaiwan[1]and the coeval extinct speciesT. drachukiifrom theMcAbee Fossil BedsnearCache Creek, British Columbia.[2]
Taxonomy
[edit]Description of the new species by Dr. Kathleen B. Pigg,Wesley Wehr,and Stefanie Ickert-Bond was based on the study of 11 complete and 55 partialcompression fossilspecimens with theholotypespecimen, number "SR 98-02-01", being housed in theStonerose Interpretive Center,Republic, Washington.[1]They published their 2001type descriptionof the species in theInternational Journal of Plant Sciencesvolume number 162. and named the speciesnastaein honor ofCharlotte G. Nastfor her work on extinct and living members of theTrochodendrales.[1]
T. nastaehas been placed in the genusTrochodendronbased on the overall shape of the leaves, the secondary vein structure, which forms weak chevrons bracing primary veins, and the tertiary veins forming four to five sided cells.[1]However the primary veins arepalmatein structure forT.nastaerather than beingpinnateas inT. aralioides.[1]
Trochodendronshares withTetracentronthe very unusual feature inangiosperms,of lackingvessel elementsin itswood.This has long been considered a very primitive character, resulting in the classification of these two genera in a basal position in the angiosperms; however, genetic research by theAngiosperm Phylogeny Grouphas shown it to be in a less basal position (early in theeudicots), suggesting that the absence of vessel elements is a secondarily evolved character, not a primitive one.
References
[edit]- ^abcdePigg, K.B.; Wehr, W.C.; Ickert-Bond, S.M. (2001). "TrochodendronandNordenskioldia(Trochodendraceae) from the Middle Eocene of Washington State, U.S.A. ".International Journal of Plant Sciences.162(5): 1187–1198.doi:10.1086/321927.S2CID45399415.
- ^Pigg, K.B.; Dillhoff, R.M.; DeVore, M.L.; Wehr, W.C. (2007). "New diversity among the Trochodendraceae from the Early/Middle Eocene Okanogan Highlands of British Columbia, Canada, and Northeastern Washington State, United States".International Journal of Plant Sciences.168(4): 521–532.doi:10.1086/512104.S2CID86524324.