PRINCE, LINDA M.* and W. JOHN KRESS. Smithsonian Institution, NMNH - Botany, MRC-166, Washington, DC 20560-0166. - Species boundaries in Canna (Cannaceae): evidence from nuclear ITS DNA sequence data.
Canna lilies (Canna: Cannaceae) are popular garden ornamentals
throughout warm temperate regions,especially in the eastern US and
Europe. Over 1000 named cultivars have been generated by hybridization
and cultivation over the past 200 years. One species, Canna
edulis, is grown in tropical regions around the world as an
"arrowroot" starch source for both humans and as animal
fodder. Many general plant books recognize approximately 50 species
and new neotropical species continue to be described based on
characters such as leaf, staminode, and rhizome size and shape.
Morphological research suggests the number of species is grossly
inflated. Nuclear ITS and chloroplast rpl16 intron DNA sequence
data for 22 plants representing 7 broadly-defined species were
collected. Molecular data confirm the recognition of a limited number
of species including a broadly defined Canna indica.
Morphological variation of the C. indica specimens sampled
include leaf color (green versus purple) and surface (glabrous versus
glaucous), flower color (all red, yellow with small reddish spots, or
a range of colors between these two extremes), and plant height. The
important crop plant C. edulis falls within the broad
morphological definition of C. indica. DNA data also group our
sample of C. edulis with all other C. indica
representatives. The closest relative of C. indica is the
semi-aquatic species C. glauca. Other species which warrant
specific recognition based on this study include: C. tuerkheimii,
C. jaegeriana, C. paniculata, C. iridiflora, and C.
Key words: Canna, Cannaceae, ITS, phylogeny, rpl16 intron