HARRIS, ERIC S. J.1* and TIMOTHY A. DICKINSON2. 13060 Valley Life Sciences Building, Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA 94720; 2Center for Biodiversity & Conservation Biology, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, CANADA M5S 2C6. - Investigation of hybrids in Crataegus (Rosaceae: Maloideae) using foliar flavonoids.
Hawthorns are a difficult taxonomic group. This difficulty is usually
ascribed to hybridization and apomixis. However, unlike other Maloid
genera in which hybrids are well-studied, only a few Crataegus
hybrids are really well known, and then mainly on the basis of studies
of their morphological intermediacy with respect to their putative
parents. We used leaf flavonoid data from two-dimensional thin-layer
chromatography to investigate four cases of hybridity in
Crataegus. Three known hybrids, C. monogyna x C.
punctata, C. monogyna x C. suksdorfii, and C.
macracantha x C. section Crus-galli, are confirmed
by their additive spot patterns. One new putative case in section
Coccineae is reported. The latter case illustrates the utility
of chemotaxonomic data for indicating potential cases of hybridity.
Two taxonomically interesting spots from the thin-layer chromatograms
were extracted and identified using HPLC and UV spectroscopy. These
are tentatively identified as rutin and a luteolin glucoside.
Key words: Crataegus, flavonoid patterns, hybrids, thin-layer chromatography