Fig. 6

Expression of Selaginella moellendorffii LFY genes by in situ hybridization. a Vegetative shoot apical meristem (SAM). b Reproductive SAM with arising sporophylls and sporangia primordia. c–d Consecutive developing stages of the sporangium with a developing stalk and a forming sporangial wall surrounding the sporogenous tissue. e Two sporangial wall layers enclosing the sporogenous tissue prior to meiosis. f Two sporangial wall layers and tapetum. g Sporangium after meiosis h Mature sporangium with collapsed wall layers and tapetum and fully developed spores. li = ligule, m = microphyll, sti = sporangia, sw = sporangial wall, sy = sporophyll, t = tapetum, ts = tetrads, s = spores. Black arrowheads indicate the SAM. Scale bars = 100 µm