Basic Information - Genetics, Genomics and Breeding of Crop Plants - page 19

Table 1-3 contd....

Section Series Species Common Chromosome

Name Number (n)

H. carnosus Small Fleshy 17

H. floridanus A. Florida

Gray ex Chapman 17

H. heterophyllus Variableleaf 17

Nutt.
H. longifolius Pursh Longleaf 17

H. radula (Pursh) Scraper, 17

T.&G. Rayless

H. simulans Muck, 17

E. E. Wats. Imitative

H. verticillatus Small Whorled 17

distinguishing species is so difficult. The taxonomic complexity of the genus
Helianthus stems from many different factors.
Although many botanists over the past two centuries have worked on
the systematics of Helianthus (de Candolle 1836; Torrey and Gray 1842;
Gray 1884; Dewer 1893; Cockerell 1919; Watson 1929), the most
comprehensive knowledge of the genus comes from Heiser 's extensive
morphological work and crossing studies (Heiser et al. 1969). During the
first half of the 20th century, many other botanists focused on smaller
taxonomic studies within the genus, publishing some 50 papers
characterizing Helianthus species and hybrids (Timme et al. 2007).
The genus Helianthus has been deemed to be comprised of as few as 10
species to more than 200. Linnaeus (1753) originally described nine species
in the genus. Gray (1884) recognized 42 species in North America. In the
early 20th century, Watson (1929) accepted 108 species, 15 of them from
South America. Heiser et al. (1969) recognized 14 annual species and 36
perennial species from North America in three sections and seven series, as
well as 17 species from South America. Subsequently, Robinson (1979)
transferred 20 perennial species of South American Helianthus to the genus
Helianthopsis. The taxonomic classification of Helianthus by Anashchenko
(1974, 1979) was a radical departure from all previous schemes. He
recognized only one annual species, H. annuus (with three subspecies and
six varieties), and only nine perennial species with 13 subspecies. Schilling
and Heiser (1981) proposed an infrageneric classification of Helianthus,
using phenetics, cladistics, and biosystematic procedures that places 49
species of Helianthus in four sections and six series ( Tables 1-2 and 1-3 ). The
classification of Schilling and Heiser (1981) is presented herein with the
following six modifications. First, the sectional name Atrorubens used by
Anashchenko (1974) has taxonomic priority, thus the section Divaricati E.
Schilling and Heiser is replaced by section Atrorubens Anashchenko. Second,
Helianthus exilis is recognized as a species, as opposed to an ecotype of H.