DICKINSON, TIMOTHY A. Center for Biodiversity and Conservation Biology, Royal Ontario Museum, Toronto, CANADA M5S 2C6; Department of Botany, University of Toronto, Toronto, CANADA M5S 3B2. - What IS Suksdorf's hawthorn?
In 1907 Sargent published his Crataegus douglasii var.
suksdorfii, based on Crataegus collections sent him by
Wilhelm Suksdorf. Suksdorf had noted variation in the number of
stamens in the black-fruited specimens and Sargent replied that he was
surprised to learn of a 10-stamen form with black fruit. Sargent then
ascertained that the type of Lindley's C. douglasii (grown from
seed collected by David Douglas in the Columbia River basin) in fact
corresponded to Suksdorf's 10-stamen form, and named the new 20-stamen
variety in Suksdorf's honor. Although Sargent referred to C.
punctata var. brevispina Douglas (published by Hooker in
1832) in his treatment of C. douglasii for Sylva of North
America (1892) he apparently neglected Hooker's comment that
Douglas' specimens comprised two varieties. Moreover, in his 1907
paper he mentioned that Heller had published C. gaylussacia
based on black-fruited specimens from California. What then is
Sargent's C. suksdorfii? Recent opinion has recognized only
Lindley's and Sargent's taxa, contrasting them on the basis of
correlated variation in leaf shape, thorn size, and floral
architecture. In seeking to understand the variation in floral
architecture within these black-fruited hawthorns I have attempted to
resolve what names should be applied to what phenotypes. Suksdorf
provided collections of southern Washington plants to many herbaria,
so that there are several specimens available from the individuals
referred to in the protologue for var. suksdorfii. Leaf, thorn,
and floral measurements, including Fourier analyses of leaf outlines,
reveal that this type material is distinct from both varieties
collected by Douglas, leading to a proposal for restricting the
application of Sargent's name, and resurrecting one or both of the
names proposed by Douglas and Heller to account for the phenotypes
associated with C. suksdorfii up to now.
Key words: Crataegus suksdorfii, Fourier, hawthorn, Suksdorf, typification