Spore morphology of Taenitis, Syngramma, and Austrogramme species (Pteridoideae, Pteridaceae) from South-Eastern Asia and Oceania. II

Abstract

This paper continues consideration of the spores of three paleotropical fern genera – Taenitis, Syngramma, and Austrogramme (Pteridoideae, Pteridaceae) from South-Eastern Asia and Oceania. At the second stage, we carried out a comparative scanning electron microscopy study of spores of three species of Austrogramme, four species of Syngramma, and six species of Taenitis and added information about previously studied spores of seven species of these genera. Spores of all examined species are trilete, tetrahedral or tetrahedral-globose with convex to hemispherical distal side and plane, convex or conical proximal side. The spores of Austrogramme species are the smallest, simplest in ornamentation and similar to each other. Sculpture of the proximal and distal sides are microverrucate, the surface of the spores is covered by granular deposits. Spores of most Syngrammaspecies are very similar to spores of Austrogramme species in shape and surface sculpture: their distal and proximal surfaces are microverrucate, whereas the spores of S. borneensis and S. cartilagidens have the low-tuberculate sculpture. Spores of Taenitis species are very different from the spores of Austrogramme and Syngramma. Seven of nine studied species have spores with well-expressed cingulum (T. blechnoides, T. cordata, T. diversifolia, T. interrupta, T. luzonica, T. obtusa, and T. requiniana), three species (T. cordata, T. hookeri, and T. pinnata) have spores with prominent laesural ridges. The spores have well-expressed ornamentation – tuberculate, baculate, rugate, tuberculate-rugate. The most conspicuous character of the ornamentation of spore surfaces is the presence of rodlets associated with sculpture elements. The densest rodlets are characteristic of Taenitis diversifolia, T. luzonica, T. obtusa, and T. requiniana. Spore size (equatorial diameter) ranges on average between 22 μm and 37 μm in Austrogramme, between 27 μm and 41 μm in Syngramma, and between 26 and 51 μm in Taenitis species.

Taxonomy and spore morphology of selected taxa of Cheilanthoideae and Pteridoideae (Pteridaceae) from Pakistan

“…Taxonomy and spore morphology of Cheilanthoideae and Pteridoideae (Pteridaceae, Polypodiales) have six genera with twelve taxa from Pakistan is illustrated with scanning electron microscopy. The spore morphology of Cheilanthoideae and Pteridoideae (Pteridaceae) species observed under SEM represents variations in size, shape, aperture and surface ornamentation, as described in many previous studies (Giacosa, Morbelli, & Giudice, 2004; Makgomol, 2006; Nayar & Devi, 1966, 1967; Vaganov, Gureyeva, Shmakov, Kuznetsov, & Romanets, 2018a, 2018b). Their spores are usually trilete and triangular in proximal and distal view, spheroidal, ellipsoidal, hemicircular in equatorial view; surface is often cristate, granulose, reticulate, perforate and tuberculate (Irfan, Jan, Jan, & Murad, 2021b; Vijayakanth & Sathish, 2016).…”

“…emodi), terminate more abruptly into a usually long apical segment; frond apex suddenly reduced to an abrupt, usually long drooping terminal segment; lamina unipinnate, oblong, lanceolate (Figure 6f); sori located on the overall both margins of lamina, spore trilete, triangular with laesura in proximal view, spheroidal, hemispherical at distal view with spinulose, tuberculate surface, equatorial view with equilateral flange at the middle, size 36-45 Â 37-48 μm, surface cristate, granulose, tuberculate at proximal view, granulose, cristate at distal view (Figure 10a-c). The spore morphology of Cheilanthoideae and Pteridoideae (Pteridaceae) species observed under SEM represents variations in size, shape, aperture and surface ornamentation, as described in many previous studies (Giacosa, Morbelli, & Giudice, 2004;Makgomol, 2006;Nayar & Devi, 1966, 1967Vaganov, Gureyeva, Shmakov, Kuznetsov, & Romanets, 2018a, 2018b et al ( ) and Vaganov et al (2017et al ( , 2020. The spores of Pteris cretica subsp.…”

Phylogenetic comparative morphological analysis of fern spores in subfamily Pteridoideae (Pteridaceae, Pteridophyta)

“…Their presence or their absence allows to identify taxa accurately at species rank. These results are consistent with results of the analysis of other taxa from subfamilies Ceratopteridoideae (Adeonipekun, Adebayo, & Oyebanji, 2021; Vaganov, Gureyeva, Kuznetsov, et al, 2017; Vaganov, Gureyeva, Shmakov, et al, 2017) and Pteridoideae (Adeonipekun et al, 2021; Chao & Huang, 2018; Irfan et al, 2021; Vaganov, Gureyeva, Shmakov, Kuznetsov, & Romanets, 2018; Wang & Yu, 2003; Yu et al, 2001). In general, the spores of the taxa studied are roundish‐triangular non lociniate.…”

Study on the formation mechanism of ornamentation patterns in spores and pollen as revealed by finite element method

“…However, by examining the SEM and TEM images of the plant spore wall ornamentation structures, it is evident that their structures are much simpler than those of the pollen with the exine structures clearly resembling wrinkles (Moran et al, 2007;Coelho & Esteves, 2011;Denk & Tekleva, 2014;Vaganov et al, 2021). Therefore, plant spores may have relatively simple structure due to their thinner exines, and stressdriven buckling may affect their ornamentation con gurations to a certain extent.…”

“…This study indicated that fungal spore ornamentation comes from the structure of exine. Compared with fungal spore walls, the development of the plant spore and pollen walls has been relatively well studied ( Yang et al, 2020;Vaganov et al, 2021). Its formation process generally consists of three stages: the development of the callose wall, the wavy morphology of primexine and the biosynthesis and transport of sporopollenin (Wallace et al, 2011;Xu et al, 2016;Ma et al, 2021).…”