Fruit of Lepidaploa (Cass.) Cass. (Vernonieae, Asteraceae): anatomy and taxonomic implications

Abstract

Lepidaploa is a taxonomically complex genus of Vernonieae, which is difficult to delimit morphologically due to vegetative and reproductive characters that overlap with Chrysolaena and Lessingianthus. Anatomical studies of cypselae are taxonomically useful for delimiting subtribes, genera and species of Asteraceae, and especially within Astereae and Eupatorieae. Given the importance of cypselae to the taxonomy of tribes of Asteraceae, we searched for morphological patterns among the species of Lepidaploa. Using light microscopy, we analyzed fruits of 21 species of Lepidaploa to evaluate the taxonomic position of the genus and species of questionable placement in the group. Our results showed that the morphologies of the cypselae of species of Lepidaploa are homogeneous and similar to other species of Vernonieae. However, pappus vascularization and the number of mesocarp layers could be useful for differentiating the sister groups Chrysolaena, Lepidaploa and Lessingianthus, which present similar macro-and micro-morphological, palynological and chromosomal characters. Also, the presence of glandular trichomes and idioblasts in the cypsela, and lignified cells in the carpopodium exocarp, can be used to separate closely related species.

Comparative cypsela morphology in Campuloclinium DC. and contributions to Eupatorieae tribe (Asteraceae) systematics

“…In the cypsela, the biseriate tector trichome (twin hairs) are common in most Asteraceae genera (Hess 1938, Robinson 2009, but glandular trichomes can also be found (Marzinek & Oliveira 2010, Angulo et al 2015, Via do Pico et al 2016, Silva et al 2018, Marques et al 2018a, b, 2020, Grossi et al 2020. The presence or absence of tector and glandular trichomes has successfully been used for the delimitation of genera and species in several groups within Asteraceae, including Eupatorieae (Marzinek & Oliveira 2010, Angulo et al 2015, Freitas et al 2015, Via do Pico et al 2016, Silva et al 2018, Marques et al 2018a, b, 2020, Grossi et al 2020. In Campuloclinium, all species present tector trichomes in ribs and glandular trichomes in interribs.…”

“…Until now, the carpopodium anatomy has shown little variation within Asteraceae (Marques et al 2020). In some cases, as reported by Silva et al (2018) and Marques et al (2018aMarques et al ( , 2020, the carpopodium exocarp lignification can be useful for species separation, but in Campuloclinium this character does not present taxonomic value because it occurs in all species.…”

“…The position of Campuloclinium remains uncertain within Eupatorieae. King & Robinson (1987) placed Campuloclinium in Gyptidinae, and Robinson et al (2009) Marques et al (2018aMarques et al ( , 2020 reinforce the importance of more morphological and phylogenetic studies, as the current circumscription of these genera should be revised (Marques et al 2020).…”

“…The fruits of Asteraceae, known as cypselae, arise from the inferior ovary (Marzinek et al 2008). The cypselae have a high classification value in different hierarchical levels in the family (Angulo et al 2015, Freitas et al 2015, Via do Pico et al 2016, Silva et al 2018, Marques et al 2018a, b, 2020, Bonifácio et al 2019, Grossi et al 2020 and the anatomical studies of these structures have contributed to solving taxonomy problems (Marzinek & Oliveira 2010, Freitas et al 2015, Silva et al 2018, Marques et al 2018a, b, 2020, Bonifácio et al 2019.…”

Seed ontogeny in Eupatorieae: development and functional aspects

“…; Marques et al. ), Senecioneae (Pandey & Singh ), Heliantheae (Pandey & Singh ), and Eupatorieae (Pandey & Singh , , ; Silva et al. ), ontogenetic analyses focusing mainly on seeds are still rare (see Kapil & Sethi ; Franca et al.…”