Because ISSRs have been used for both species- and population-level studies within the genus Dirca (Schrader and Graves, 2004; Graves and Schrader, 2008), we used them to study genetic variation within and among geographically disparate populations of Dirca palustris.
Our goal was to test the hypothesis that gene flow among populations of Dirca palustris was historically limited, and not the product of more recent fragmentation, by characterizing phenotypic and genetic variation within and among five natural populations and relating the observed variation to the environment and geography.
On each branch, we also measured the internode between the terminal and first subterminal inflorescence, the length of the thorn-like spur that arises from the terminal position on branches of Dirca (Graves, 2006), and the basal diameter of the stem that formed in 2009.
(North Dakota), after leaves in the overstory had fully expanded and when Dirca palustris were similar phenologically at all sites (Table 1).
From each population we collected fully expanded leaves from 19 mature Dirca palustris selected to represent the spatial distribution of plants within the population.
1 is an overall, radial longitudinal view of a water-conducting cell or vessel member in the wood of Dirca palustris.
5), and for the most part, Dirca palustris does not, although sometimes very small amounts of vesturing (best described as obscure) can be observed (Fig.
Although Daphne and Wikstroemia are within the same tribe (Daphneae, Table 1), so are Edgeworthia and Dirca but neither of the latter two genera possess tori (Dute et al, 1996; the present study).
Clearly, in this study the circularity ratio is much less for pit apertures of Pimelea and Gnidia than for Daphne and Dirca. The former genera have slit-like apertures and have no tori.
(Dute el al., 1992; Ohtani & Ishida, 1976), vessel pits of Dirca and Ovidia (Record & Hess, 1943), and Aquilaria agallecha (Rao & Dayal, 1992).