Megaspore morphology in the Selaginellaceae in a phylogenetic context: A study of the megaspore surface and wall structure using scanning electron microscopy

A classification of Selaginella (Selaginellaceae) based on molecular (chloroplast and nuclear), macromorphological, and spore features

“…65 Asian species of Seleginella (for voucher information see Appendix 1) was observed using a QUANTA 200 scanning electron microscope (FEI Co., Hillsboro, Oregon, U.S.A.), and gold-palladium plating was performed using a BAL-TEC SCD 005 cool sputter coater (BAL-TEC, Liechtenstein) at Yunnan University, Kunming, China. Additional data on spore morphology were taken from literature (e.g., Reeve, 1935;Minaki, 1984;Liu & al., 2001Tryon & Lugardon, 1991;Giorgi & al., 1997;Chang & al., 2002a, b;Li & al., 2003;Liu & Yan, 2004, 2005Chu, 2006;Korall & Taylor, 2006;Zhao & al., 2006a, b;Singh & al., 2014). The terminology of ornamentation of spore surfaces followed Huang (1981), Minaki (1984), Tryon & Lugardon (1991), Chu (2006), Korall & Taylor (2006), and Punt & al.…”

“…(2004) Jermy (1986) and members of this section share some morphological and spore features (Figs. 1C, 3C): (1) the reticulate megaspore surfaces have wing-like and highly convoluted laesurae forming a complex mass at the pole (Stefanović & al., 1997;Korall & Taylor, 2006;Schulz, & al., 2013); (2) the globose-triangular microspores have coarse proximal surfaces, sometimes covered with fine spines, and the distal surfaces are usually regulate (for microspore morphology of S. pygmaea Alston, see Schulz & al., 2013; for that of S. moratii Rauh & W.Hagemann and S. polymorpha Badré, see Stefanović & al., 1997); (3) the sterile stem leaves are monomorphic and decussately arranged; (4) rhizophores strictly restricted to the base of erect stems; and (5) chromosome number 2n = 18 as far as known (for chromosomes of S. uliginosa and S. lyallii see Jermy & al., 1967).…”

“…1D, 3D, 5B, N), members of this section share spirally arranged monomorphic sterile leaves, decussate sporophylls (Jermy, 1986;Soják, 1993) and the absence of axillary leaves. Their megaspore surfaces often have an interwoven, closed, irregular, and fine reticulum, and sometimes the muri are not obvious (Tryon, 1949;Minaki, 1984;Chu, 2006;Korall & Taylor, 2006;. The microspore proximal surfaces have a rough and irregularly Version of Record rugulate ornamentation and distal surfaces are verrucate and rugulate Chu, 2006;.…”

“…four species including the American species S. lepidophylla. Morphologically, members of this section have dorsal leaves and ventral leaves similar in size and shape (Mickel & al., 2004), distal surfaces of the megaspores with high ridges and proximal surfaces reticulate forming connected ridges (Korall & Taylor, 2006), and microspores scattering in tetrads surrounded and ornamented by several ridges Giorgi & al., 1997;Mickel & al., 2004). Following Mickel & al.…”

“…(1) Presence of articulations or swollen joints below bifurcation of the stem; (2) A single large megasporangium located at the base of a strobilus; (3) Megaspore surfaces with irregular or regular and coarse reticulum usually with high and wide muri (e.g., Minaki, 1984;Giorgi & al., 1997;Korall & Taylor, 2006;; (4) Large megaspores; and (5) Microspore surfaces usually with spines (e.g., Tryon & Lugardon, 1991;Giorgi & al., 1997; Spring (1840) and thus is the type of the section (Art. 40.3;.…”