Habitat
Alluvial woods and riverbanks with calcareous soils, rocky calcareous woods, shaded calcareous ledges, and rich loamy woods (Braun 1967, Voss 1972, Van Bruggen 1976, Weakley 2000). Most populations are within the boundaries of previously glaciated territory (exceptions are extreme eastern and western populations.)
Reproduction
Trillium seeds have an elaiosome, an oily, lipid-rich attachment that is highly attractive to ants, including Formica neogates and Aphaenogaster rudis. The ants carry the seeds to their nest, eat the attachment, and leave the seeds in tunnels in their nests (FNA 2002a, Leege et al. 2010). The seeds later germinate en masse (Case and Case 1997). Yellow jackets (Vespula spp.) and other wasps are similarly attracted to the elaiosome. Yellow jackets are documented seed dispersers for three species (T. catesbaei, T. cuneatum, T. undulatum) (Zettler et al. 2001). Ants carry the seeds an average of about 1m whereas yellow jackets disperse seeds an average of 1.4m (Chafin 2010, Zettler et al. 2001). Long distance dispersers include mammals, such as white-tailed deer (Odocoileus virginianus) and woodchucks (Marmota monax) (Chafin 2010, Vellend et al. 2006). Similarly, it is suspected that elk (Cervus canadensis) and mule deer (Odocoileus hemionus) of the western U.S.A. are capable of dispersing seeds over long distances (Bartuszevige and Endress 2008).
All Trillium have rhizomes but the frequency of asexually reproduction varies (Chauhan et al. 2019, FNA 2002a, Ohara 1989).
Trillium seeds exhibit a somewhat unique kind of dormancy called deep simple double morphophysiological dormancy, meaning they require two winters and one summer to complete dormancy break. After dispersal, roots (radicles) emerge in the first spring and leaves (epicotyls) begin growing in the second spring. The result is that Trillium seeds are generally about 1.5-2 years before they are non-dormant. If root emergence does not occur during the first spring, the next opportunity for root emergence would be the third spring and epicotyl emergence would occur during the fourth spring after dispersal (Walck et al. 2005). Age to maturity, or flowering, is variable and has been recorded from 4 to 20 years depending on growing conditions (Case and Case 1997).