The Tall Flat-topped White Asters
Doellingeria Nees includes only three x=9 species all native to eastern North America. The genus is distinguished by its fruit pappi, phyllaries, inflorescence shape and the brachidodromous leaf venation. Cypselae (achenes) have a quadruple pappus consisting of: 1) short bristly scales (secondary outer series), 2) mid length bristles with attenuate tips (secondary inner series), 3) longer bristles with attenuate tips (primary outer series), and 4) the longest innermost bristles with strongly clavate (flattened and widened) tips (Semple & Hood 2005). The quadruple pappus appears to be the primitive state within the North American Clade. Phyllaries are narrow with a chlorophyllous zone of narrow bands along the raised midvein. The arrays of heads are corymbiform. The leaves have a well developed prominent near-marginal connected network of lateral veins forming the distinctive brachidodromous pattern.
The genus was recognized as distinct from Aster in floras in the late 1800's and early 1900's, but subsequently was generally included in Aster s.l. following Gray (1884). Semple, Chmielewski and Leeder (1991) treated the eastern North America species as Aster sect. Triplopappus following Jones (1980) and Semple and Brouillet (1980). Nesom (1993) reviewed the taxonomy of the genus and divided it into two sections. In the RFLP cpDNA study by Xiang and Semple (1996) Eucephalus was the sister group to Doellingeria, but the study did not include other genera that may be more closely related to Doellingeria than Eucephalus. Brouillet, Allen, Semple and Ito (2001) determined that only the eastern North American species were related to Eucephalus. The representative eastern Asian species included in their study were all members of the Aster clade and thus do not belong in the genus Doellingeria which includes only species of the North American Clade of the Astereae (Brouillet et al. 2009).
revised 10 May 2013 by J.C. Semple
© 2013 J.C. Semple, including all photographs unless otherwise indicated