Comparative anatomical study of two Malvaceae species from a seasonally dry forest

• Published in: Flora. Morphologie, Geobotanik, Oekophysiologie Geobotanik, Oekophysiologie, 2023-06, Vol.303, p.152290, Article 152290
• Main Authors: Silva, Pâmela Clemente de Meneses, Gallão, Maria Izabel, de Arruda, Emília Cristina Pereira
• Format: Article
• Language: English
• Subjects: Caatinga; Malva rasteira; Mela-bode; Secretory structures; Semiarid environments; Trichomes
• ISSN: 0367-2530; 1618-0585
• DOI: 10.1016/j.flora.2023.152290

•Herissantia tiubae and H. crispa present a diversity of trichomes that great potential of species for future taxonomic and ecological studies.•The presence of secretory structures, indicate the great potential of species for future pharmacological and ecological studies.•The present work brings new contributions to the anatomy of Malvaceae and of the Herissantia genus. An comparative study anatomical was carried out with Herissantia tiubae, popularly known as “mela-bode”, and H. crispa, known as “malva-rasteira”, occurring in a seasonally dry forest in the state of Pernambuco. For this, free-hand cross-sections were made, stained with safrablue, mounted in glycerin, and analyzed under light microscopy. Scanning electron microscopy was used to visualize the three-dimensional structures of the epidermal surface. The two species presented a great diversity and abundance of eglandular, mainly stellate, trichomes, which is a synapomorphy of Malvaceae, in addition to glandular trichomes on stems and leaves. As in other species of the family, secretory structures that exude secondary compounds with medicinal importance – which deserve further investigation – were also observed in H. tiubae and H. crispa. Trichomes were classified into two eglandular (stellate and unicellular) and three glandular (pedunculate, filiform, and globular) types. Other observed anatomical characters which are common in Malvaceae, were stomata type, mucilaginous cavities, druses, and dorsiventral mesophyll. The characters that differentiated the two studied species were: uniseriate filiform pyriform glandular trichomes exclusively present on stems and leaves of H. crispa, this being the first report in the species; and starch-storing parenchyma exclusively present in stems of H. crispa; and anomocytic stomata exclusively present in H. tiubae. Characteristics related to cuticle thickness, position of trichomes and stomata, and the presence of druses and starch-storing parenchyma may have adaptive relevance for both species as they help them survive during periods of physiological stress typical of the semiarid conditions of the Caatinga. These data contribute to the biological knowledge of the studied species in seasonally dry tropical forests and provide support for future pharmacological, taxonomic, and ecological research.