Ephedra tweediana C.A.Mey.
| Integration of Morphological and Ribosomal RNA Data on the Origin of Angiosperms James A Doyle, Michael J Donoghue and Elizabeth A Zimmer (1994) Annals of the Missouri Botanical Garden 81: 419-450 | |
| Functional Constraints and rbcL Evidence for Land Plant Phylogeny Victor A Albert, Anders Backlund et al. (1994) Annals of the Missouri Botanical Garden 81: 534-567 |