Cladistic analysis of Portulacaceae supports a revised taxonomy of Calandrinia sensu lato. Calandrinia, as here circumscribed, comprises ca. 14 western American species in three sections: Calandrinia, Acaules, and Monocosmia. Previous taxonomies classified over 100 species in Calandrinia but recognized Monocosmia as a distinct genus. Calandrinia sects. Calandrinia and Monocosmia are probably cladistically nested in section Acaules and are not sister groups of either Rumicastrum or Montia, as proposed in a previous cladistic analysis. Montiopsis Kuntze, traditionally included in Calandrinia, comprises ca. 15 western South American species in two subgenera, Montiopsis and Dianthoideae (...)

Revised circumscriptions and subgeneric taxonomies of Calandrinia and Montiopsis (Portulacaceae) with notes on phylogeny of the portulacaceous alliance

Background and Aims In spite of recent phylogenetic analyses for the Chenopodiaceae–Amaranthaceae complex, some morphological characters are not unambiguously interpreted, which raises homology questions. Therefore, ontogenetic investigations, emphasizing on ‘bracteoles’ in Atripliceae and flowers in Chenopodioideae, were conducted. This first paper presents original ontogenetic observations in Beta vulgaris, which was chosen as a reference species for further comparative investigation because of its unclarified phylogenetic position and its flowers with a (semi-)inferior ovary, whereas all other Chenopodiaceae–Amaranthaceae have hypogynous flowers. Methods Inflorescences and flowers were examined using scanning electron microscopy and light microscopy. Key Results Floral development starts from an inflorescence unit primordium subtended by a lateral bract. This primordium develops into a determinate axis on which two opposite lateral flowers originate, each subtended by a bracteole. On a flower primordium, first five tepal primordia appear, followed by five opposite stamen primordia. Simultaneously, a convex floral apex appears, which differentiates into an annular ovary primordium with three stigma primordia, surrounding a central, single ovule. A floral tube, which raises the outer floral whorls, envelops the ovary, resulting in a semi-inferior ovary at mature stage. Similarly, a stamen tube is formed, raising the insertion points of the stamens, and forming a staminal ring, which does not contain stomata. During floral development, the calyces of the terminal flower and of one of the lateral flowers often fuse, forming a compound fruit structure. Conclusions In Beta vulgaris, the inflorescence is compound, consisting of an indeterminate main axis with many elementary dichasia as inflorescence units, of which the terminal flower and one lateral flower fuse at a later stage. Floral parts develop starting from the outer whorl towards the gynoecium. Because of the formation of an epigynous hypanthium, the ovary becomes semi-inferior in the course of floral development.

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Floral and inflorescence morphology and ontogeny in Beta vulgaris, with special emphasis on the ovary position

Plant anatomy: at the heart of modern botany

Premise of research. Staminodes are infertile stamens that have evolved numerous times in angiosperms and exhibit a vast array of forms and functions. Variation in staminodes suggests that numerous...

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Evolution and Development of Staminodes in Paronychia (Caryophyllaceae)

Structure of long-tubed white corollas: A case study from the trumpet-creeper family (Bignoniaceae)

Gynoecium structure and development in core Caryophyllales: a matter of proportions

Asterids are subdivided into two main groupings: basal asterids (a grade) consisting of Cornales and Ericales, and euasterids (with Lamiids and Campanulids) (Figs. 11.1, 11.2; e.g. Judd and Olmstead, 2004). Spichiger et al . (2002) distinguished between archaic asterids, superior hypogynous asterids and superior epigynous asterids. Characters common in a majority of taxa of asterids are sympetaly with adnate stamens (stamen-petal tube), unitegmic, tenuinucellate ovules, cellular endosperm formation, terminal endosperm haustoria, pollen that is released at the trinucleate stage, and the presence of iridoids (e.g. Judd and Olmstead, 2004; Soltis et al ., 2005). Apart from sympetaly, the other characters cannot be used in floral diagrams. Most taxa share the development of a ring primordium in early stages of development (Erbar, 1991) indicating a generalized syndrome of petal development (see p. 34). Core asterids (euasterids) share sympetaly, a bicarpellate gynoecium and haplostemony, while the basal orders Cornales and Ericales are much more variable with a basically diplostemonous androecium. Basal asterids: Cornales, Ericales Cornales The basalmost order of asterids (Fig. 11.2) contains six to seven families, with three main families Hydrangeaceae, Cornaceae and Loasaceae. All share small sepals, an inferior ovary, epigynous disc nectary, and often drupaceous fruits (Soltis et al ., 2005). Soltis et al . (2005) argued that the half-inferior ovary of Hydrangeaceae evolved from epigyny common in the clade. Most Cornales have free petals, with the evolution of a corolla tube in a few Loasaceae.

Ronse De Craene

Papers

Gynoecium structure and development in core Caryophyllales: a matter of proportions

Floral Diagrams: Asterids: tubes and pseudanthia