Morphophysiological dormancy in seeds of three eastern North American Sanicula species (Apiaceae subf. Saniculoideae): evolutionary implications for dormancy break

Abstract

Dormancy breaking and germination requirements were determined for seeds of the eastern North American (eNA) species Sanicula canadensis, Sanicula gregaria and Sanicula trifoliata, and the data compared to those available for the European-Asian (EurA) congener Sanicula europaea. Seeds of the three eNA species had underdeveloped embryos that were physiologically dormant, i.e., morphophysiological dormancy (MPD). Warm (25/15°C) followed by cold (5/1°C) stratification was effective in breaking dormancy in 100% of the S. canadensis seeds, but in only 29.3% of S. gregaria seeds and 43.3% of S. trifoliata seeds. Cold stratification alone broke dormancy in 38.7, 12.0 and 0% of S. canadensis, S. gregaria and S. trifoliata seeds, respectively. Thus, some seeds of S. canadensis and of S. gregaria that germinated have non-deep complex MPD, and others have deep complex MPD. All seeds of S. trifoliata that germinated have non-deep complex MPD. Within a phylogenetic context, the kind (level) of MPD may or may not differ between eNA Sanicula sister species because conspecific variation in the kind of MPD exists in seeds ofS. canadensis and S. gregaria. Similarly, the kind of MPD in seeds of eNA S. canadensis and S. gregaria may or may not differ with the deep complex MPD in seeds of the EurA S. europaea. However, the non-deep complex MPD in all seeds of eNA S. trifoliata and deep complex MPD in seeds of S. europaea represent a distinct difference in this trait between two of the five clades comprising the genus Sanicula.

Old sleeping Sicilian beauty: seed germination in the palaeoendemic Petagnaea gussonei (Spreng.) Rauschert (Saniculoideae, Apiaceae)

“…Sanicula in Vandelook & Van Assche () and Hawkins et al . (); Alepidea in Mulaudzi et al . (); Eryngium in Ekpong & Sukprakarn () and Necajeva & Ievinsh ()].…”

“…The presence of immature embryos has been documented for many representative species of Saniculoideae (e.g. Vandelook & Van Assche 2008;Hawkins et al 2010;Necajeva & Ievinsh 2013), and their seeds are classified as morphologically dormant (MD). We can only speculate as to whether MD Petagnaea seeds exist because there are no complete studies on the presence of underdeveloped embryos in Petagnaea seeds.…”

“…Sanicula L. in Baskin & Baskin (), Vandelook & Van Assche () and Hawkins et al . (); Alepidea F. Delaroche in Mulaudzi et al . (); Eryngium L. in Ekpong & Sukprakarn (), Curle et al .…”

“…To understand the germination phenomenon in the Apiaceae subfamily Saniculoideae, several studies have been performed on some genera [i.e. Sanicula L. in Baskin & Baskin (1988), Vandelook & Van Assche (2008) and Hawkins et al (2010); Alepidea F. Delaroche in Mulaudzi et al (2009); Eryngium L. in Ekpong & Sukprakarn (2006), Curle et al (2007) and Necajeva & Ievinsh (2013)]. To date, subfamily Saniculoideae has undergone an interesting phylogenetic rearrangement involving the following nine genera: Actinolema Fenzl, Alepidea, Arctopus L., Astrantia L., Eryngium, Petagnaea Caruel, Polemanniopsis B.L.…”

Seed germination ecophysiology of two western North American species of Sambucus (Caprifoliaceae sensu lato), and comparisons with eastern North American and European congeners

“…Differences in dormancy have been reported between eNA and European herbaceous congeners in the genera Chaerophyllum (Baskin & Baskin 1990;Baskin et al 2004;Vandelook et al 2007) and Sanicula (Vandelook & Van Assche 2008;Hawkins et al 2010). In Sanicula, the European polycarpic perennial S. europaea requires cold stratification to overcome dormancy and one eNA species, which is a monocarpic perennial, needs warm + cold strati- Table 2 Summary of the temperatures required for embryo growth and for dormancy break, germination responses to gibberellic acid (GA3) and the level of morphophysiological dormancy (MPD, sensu Baskin & Baskin 1998) for seeds of seven Sambucus taxa (sensu Cronquist et al 1984;Bolli 1994) (1969), Conrad & McDonough (1972) fication.…”