Pappus and cypsela ontogeny in Asteraceae: structural considerations of the tribal category

Abstract

Crepis japonica (L.) Benth., Porophyllum ruderale (Jacq.) Cass. and Tridax procumbens L. are weedy species that grow in cultivated fields, roadsides, abandoned fields and open, disturbed spaces in Maringa, Parana state, Brazil. The ontogeny of the fruits and seeds of the 3 Asteraceae species was carried out. The flowers and developing fruits were prepared according to resin inclusion techniques for histochemical tests and scanning electron microscopy. During maturation of the pericarp, processes such as trichome differentiation, tissue sclerification, phytomelanin deposition and breakdown of tissues can be observed. The fruit of C. japonica is entirely lacking in phytomelanin. The seed is only exotestal in C. japonica. Comparative analysis of the pappus and cypsela characters demonstrated that they are efficient in separating species and tribes. The seed coat and embryo may also be useful in the characterization of tribes.

Cypsela micromorphology and anatomy in Cirsium sect. Epitrachys (Asteraceae, Carduoideae) and its taxonomic implications

“…Achene morphology provide relatively constant characters that is relatively less affected by the growth environment (Sears 1922). Cypsela is the term used for the fruits of Asteraceae, differing from the achene by presence of an additional layer over the pericarp (inferior ovary) (Spjut 1994, Barroso et al 1999, Marzinek et al 2008, Frangiote-Pallone and Souza 2014. Cypsela external morphology and anatomy have been widely used in elucidating taxonomic relationships in Compositae (Lavialle 1912, Stebbins 1953, Barthlott 1984, Singh and Pandey 1984, Bruhl and Quinn 1990, Glynis 1993, Geng et al 1994, Blanca and Guardia 1997, Zhu et al 2006, Garg and Sharma 2007, Pandey and Kumari 2007, and the tribes Cynareae (Kadereit and Jeffrey 2007) and Cardueae (Dittrich 1977, Häffner 2000, Zarembo and Boyko 2008, Abid and Qaiser 2009, Abid and Ali 2010.…”

Sepal Identity of the Pappus and Floral Organ Development in the Common Dandelion (Taraxacum officinale; Asteraceae)

“…Other indications for bundles to or in the pappus have been reported for some species, for instance, in Microseris bigelovii (Lactuceae), which has a five-part pappus, and M. pygmaea , with a ten-part pappus, a constant number of ten pro vascular bundles were found [ 75 ]. In some other Asteraceae, including Porophyllum ruderale (Heliantheae, Asteroideae) and Tridax procumbens (Heliantheae alliance) the presence of veins in pappus parts were reported [ 76 ]. Thus, the vascular system in Asteraceae shows a number of adaptations depending on the type of pappus and the need for their supply.…”

Centaurea kirikkalensis (Asteraceae), a new species from Turkey

“…The exine structure and sculpturing, pollen shape, the presence of single‐ or double‐layer columellae, costae thickness and spine length are also of significance for the taxonomy of the genus Centaurea and related some genera (Özler et al 2009, Erkara et al 2012, Shabestari et al 2013, Başer et al 2019, Çıtak et al 2019, 2021). The achene surface pattern, the presence of hair on the achene, the length, color and form of the connection area of the hilum, achene shape, size and color, the length and color of pappus and hilum position have been used for the classification of various species (Mukherjee and Sarkar 2001, Talukdar 2013, Frangiote‐Pallone and Souza 2014, Bona 2015b, Candan et al 2016, Şirin et al 2017, Özcan and Akinci 2019, Rakizadeh et al 2019, Adwan et al 2020).…”