I don’t know whether this applies to our west coast erythroniums. It would be good for someone to test them. The information I have is for Asian and eastern North American species. Ecophysiology of seed germination in Erythronium japonicum (Liliaceae) with underdeveloped embryos http://www.amjbot.org/cgi/content/full/89/11/1779/ by Tetsuya Kondo, Nori Okubo, Taku Miura, Kazushige Honda and Yukio Ishikawa. They tested many variables and combinations of variables - constant, alternating or variable temperatures, and light. They had many lab experiments, and also outdoor pot experiments. They didn’t just observe the outside of the seeds, but also sliced them open to see what was happening to the embryos. They found that Erythronium japonicum seeds are not able to germinate as soon as they are shed, because the embryos are immature. They require a hot period for the embryo to lengthen, then a cooling period for germination. Seeds would germinate if given 90 days at 25C, then 5C, or if they were kept around 10C (or 15C days/5C nights). They did not germinate if kept at these temperatures: 0, 5C, 15C, 20C or 20C days/10C nights . [In incubators, seeds did not germinate at 20/10 (light 12 h/dark 12 h alternating temperature), 20, 15, 5, or 0C with a 12-h light photoperiod for 200 d. They germinated at 15/5 or 10C, starting on day 135. If seeds were kept at 20 or at 25/15C before being exposed to 5C, the seeds germinated, but if kept at 25 or 30C they did not. Embryos at 25/15C grew to half the seed length without germinating; at 0 or 5C, embryos elongated little. Embryos grew and seeds germinated when kept at 25/15C for 90 d and then at 5C.] In nature, the seeds have germinated by November, and seedlings emerge as the snow melts in spring. There are other species that also have immature embryos, E. albidum, E. grandiflorum, E. americanum, and E. rostratum. Their temperature requirements differ, and their embryo elongation is either later, or carries on later (closer reading of the article needed here.) The bibliography lists papers on germination of these Eastern U.S. species. _______________________________________________ pbs mailing list pbs@lists.pacificbulbsociety.net http://lists.pacificbulbsociety.net/cgi-bin/… Unsubscribe: <mailto:pbs-unsubscribe@lists.pacificbulbsociety.net> PBS Forum https://…