Allium cernuum - nodding onion
Allium is a large genus in the pacific northwest. Species generally have seeds with physiological dormancy which is overcome with 8+ weeks of cold stratification or have seeds that are nondormant. Several species of Allium native to California do not need pretreatments to germinate but populations may be south of the PNW which may reduce selection pressure for seed dormancy (Emery 1988). Germination in Allium generally occurs at cooler temperatures (Specht and Keller 1997). Of all the native species in the PNW, Allium acuminatum is the most studied and is commonly used in restoration projects. Fruits of Allium are capsules that open at maturity and the seeds are relatively large, rounded, and black (FNA 1993+). Allium are generally early flowering and fruiting species. Seeds and capsules that readily dislodge from the plant are mature. In Allium acuminatum, as with many species of Allium, fruits turn from green when immature to brownish when mature.
References
Emery 1988. Seed propagation of native California species. Santa Rosa Botanical Garden.
[FNA] Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico [Online]. 21+ vols. New York and Oxford. Vol. 1, 1993; vol. 2, 1993; vol. 3, 1997; vol. 4, 2003; vol. 5, 2005; vol. 7, 2010; vol. 8, 2009; vol. 19, 2006; vol. 20, 2006; vol. 21, 2006; vol. 22, 2000; vol. 23, 2002; vol. 24, 2007; vol. 25, 2003; vol. 26, 2002; vol. 27, 2007; vol 28, 2014; vol. 9, 2014; vol. 6, 2015; vol. 12, 2016; vol. 17, 2019. Website http://beta.floranorthamerica.org. [accessed February 2022].
Specht C, Keller E. 1997. Temperature requirements for seed germination in species of the genus Allium L. Genetic Resources and Crop Evolution 44:509-517.