Host communities in natural ecosystems can be highly heterogeneous, impacting parasite evolution. In theory, low host heterogeneity favors parasite specialization, whereas high host heterogeneity favors generalism (Futuyma and Moreno 1988). However, strong empirical support for this phenomenon comes from relatively few systems (Legros and Koella 2010, Fecchio et al. 2018, Gibson et al. 2020) and even fewer at continent scale. With well-characterized host community distributions (Monfreda et al. 2008), and host cultivation patterns strongly tied to abiotic gradients (Fig. 2), S. hermonthica parasitic plants are a valuable system for developing a predictive framework of host specialization. Unlike well-studied microbial parasites with short generation times (Penczykowski et al. 2016), S. hermonthica may be able to maintain long-term adaptive potential due to a long-lived seedbank (>10 yrs; (Bebawi et al. 1984) and substantial genetic diversity from its outcrossing breeding system (Bozkurt et al. 2015, Unachukwu et al. 2017). Whereas repeated selection could exhaust parasite genetic diversity under limited migration and mutation, longer parasite generation times relative to hosts (driven by a long-lived seedbank) help maintain parasite diversity and promote adaptation to changing environments (Gandon and Michalakis 2002).