Dubautia knudsenii Hillebr. , Fl. Hawaiian Isl. 223. 1888.
Type information:
Lectotype [B]. V. Knudsen s.n.. Kaua`i: on the mountains of Waimea or at Halemanu.
Lectotypified in Sherff. Bernice P. Bishop Mus. Bull. 135: 104. 1935.

Note: Lectotype: fragment BISH!, photos BISH!, F! If the original set of Hillebrand's specimens is taken to have been at B, then the BISH specimen is a fragment of the holotype, rather than the fragment of the lectotype WLW, 1/95).

=Dubautia knudsenii subsp. knudsenii
Note: Lectotype: fragment BISH!, photos BISH!, F! If the original set of Hillebrand's specimens is taken to have been at B, then the BISH specimen is a fragment of the holotype, rather than the fragment of the lectotype WLW, 1/95).

*Verification: None.

Dubautia knudsenii Hillebr. subsp. filiformis G.D. Carr, Allertonia 4: 84. 1985.
Type information:
Holotype [BISH]. MacDaniels 672. 13 February 1927. Kaua`i: Kekoiki Ridge, above Kilauea, rain forest.850m. Isotype(s) [US!].
=Dubautia knudsenii subsp. filiformis

*Verification: R.K. Shannon.

Dubautia knudsenii Hillebr. subsp. nagatae (H. St. John) G.D. Carr, Allertonia 4: 83. 1985. Flora of the Hawaiian Islands --Basionym
Type Information
Dubautia nagatae H. St. John , Bull. Torrey Bot. Club 106: 1 1979.
Kaua`i: Alaka`i near Koaie Stream gauge, in moss forest. 3800 ft. 2 September 1973. K. Nagata 1182.
Holotype [BISH]. Isotype(s) [BISH!, HLA, K!, US].
=Dubautia knudsenii subsp. nagatae

*Verification: R.K. Shannon.
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*Verification: R.K. Shannon.

Dubautia knudsenii Hillebr. var. degeneri Sherff, Bot. Gaz. (Crawfordsville) 96: 151. 1934.
Type information:
Holotype [F]. O. Degener 4259. 8 May 1928. Moloka`i: [northeastern Moloka`i], N of Pepe'opae bog, open rain forest. Isotype(s) [NY [mfc!]].

Note: There are three sheets of Degener et al. 4259 at US that are all collections of Bidens populifolia, collected 6 Nov. 1932 (one sheet has date of 1933).

=Dubautia laxa subsp. laxa
Note: There are three sheets of Degener et al. 4259 at US that are all collections of Bidens populifolia, collected 6 Nov. 1932 (one sheet has date of 1933).

*Verification: R.K. Shannon.