Morphology and taxonomy of leaf papillae and mammillae in Pottiaceae of China

Abstract

Both papillae and mammillae are important structural characteristics for Pottiaceae classification, but these characters are diverse and their nomenclature is confused, hindering the classification of Pottiaceae. So, we selected representative species that cover all types of papillae and mammillae of Chinese Pottiaceae and observed and compared differences between them using light and scanning electronic microscopy. We corrected the chaotic descriptions of papillae of representative species, and have provided a uniform set of terms (“simple”, “forked”, “branched”, and “pedicellate”) to describe the shapes of papillae. In addition, we described how to quickly and accurately use papillae and mammillae to classify representative species in Chinese Pottiaceae.

Ultrastructure of Lejeunea spp. leaves surface in a lowland tropical urban forest of Universitas Indonesia Campus, Depok, Indonesia

“…Mamillae-shaped cell surface ornamentation is only found in L. catanduana. The shape of the mamillae of L. catanduana is almost the same as the shape of the mamillae in the species Gymnostomum calcareum which has an elongated shape like a rope (Kou et al 2014). Even though Lejeunea catanduana is a synonym of L. anisophylla, in this study, they have a different character in the leave cell surface.…”

Phylogeny and divergence time estimation of the genus Didymodon (Pottiaceae) based on nuclear and chloroplast markers

“…species commonly have papillae on leaf cells. Papillae are outgrowths of the moss leaf cell wall or cuticle, and the presence or absence, appearance, number, density, size, and distribution of papillae have been widely used in Pottiaceae classification (Câmara & Kellogg, 2010;Kou et al, 2012Kou et al, , 2014. Our results show that there are different kinds of papillar structures in the species within each separated genus, including multiple papillae, sparse papillae, simple papillae, and no papillae, but the species with papillae originated earlier than those with a smooth leaf surface.…”

“…R.H.Zander, section Rufidulus (Chen) R.H. Zander, section Didymodon and section Vineales (Steere) R.H.Zander. Didymodon species generally have typically morphological features that provide resistance to drought conditions such as turf‐forming ability, strong central strands, thin laminal cell walls, and increased guide cells and massive papillae which can promote water transportation and avoid damage from solar radiation (Zander, 1993; Kou et al, 2014). Didymodon is always considered a xerophytic functional group as the main components of soil biocrusts can increase soil stability through binding soil and sand particles and increase soil fertility and carbon fixation by the capture of nutrient‐rich dust (Bao et al, 2019; Guo et al, 2020; Kou et al, 2020).…”

Biocrusts protect the Great Wall of China from erosion

“…As pioneer species with exceptional stress resistance, cyanobacteria have evolved a robust cell wall and often protect themselves in gelatinous masses of EPS against desiccation and radiation, and they have the ability to isolate themselves from detrimental microhabitats through phototaxis ( 30 , 31 ), making them well suited to growth on the surface of the Great Wall. Similarly, some mosses have developed specialized drought-tolerance structures, such as C-shaped or circular cell papillae ( 32 ), which have the mechanisms of reflecting radiation and promoting water conduction ( 33 ), thus enabling them to adapt to environmental stress on the Great Wall featuring high temperatures, drought, and intense solar radiation. Therefore, the stable colonization and long-term development of biocrusts on the Great Wall can be essentially attributed to the stress resistance of cyanobacteria and mosses within it.…”