279 
NAMED HYBRIDS 
The following is not an exhaustive list of the hybrids that have 
been documented in the Missouri flora. Rather, it includes only 
those hybrids that have been assigned binomials (as opposed to those 
that are only listed as species A x species B), so as to account for the 
epithets that appear in the taxonomic and floristic literature. The 
presumed parentage for each hybrid is listed, although in most cases 
the actual parentage has not been confirmed. Some species that are 
of presumed hybrid origin, such as Apocynum medium, but are fertile 
and of widespread distribution, have been retained in the main 
portion of the catalogue and are not listed with a cross sign (x) 
before the species epithet. 
ASPLENIACEAE 
Asplenium x ebenoides Scott, Scott’s spleenwort (A. platyneuron 
x A. rhizophyllum), p. 31 
Asplenium x gravesii Maxon, Graves’ spleenwort (A. bradleyi x 
A. pinnatifidum), p. 32 
ASTERACEAE 
Aster x amethystinus Nutt. (A. ericoides x A. novae-angliae), 
. 1516 
Eupatorium x truncatum Muhlenb. ex Willd. [S: E. perfoliatum Le 
var. cuneatum (Engelm. ex Torrey & A. Gray) Engelm. 
ex A. Gray; M: E. x polyneuron (F. J. Herm.) 
Wunderlin} (Wunderlin, 1972; Cronquist, 1980; Tucker 
and Dill, 1989), p. 1464 
Helianthus x cinereus Torrey & A. Gray Var. sullivantii Torrey & 
A. Gray (H. mollis x H. occidentalis), p- 1571 
Helianthus x laetiflorus Pers. (H. rigidus * H. tuberosus), 
: p. 1570 ae 
Vernonia x illinoensis Gleason (V. gigantea * V. missurica) 
(Faust, 1972, 1977) 
S: Steyermark G: Great Plains Flora M: Mohlenbrock 
