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Aechmea (Bromeliaceae) is a large genus with controversial systematics and distinct flower shapes and pollinators. We explored floral anatomy and development in two Aechmea spp. belonging to different subgenera to contribute useful information on reproductive biology and taxonomy. We examined floral buds using scanning electron and light microscopy to characterize the development of septal nectaries, petal appendages, ovules, stamens and carpels. In A. gamosepala, we confirmed that the petal appendages develop late, whereas in A. correia-araujoi they develop earlier during floral development. Petal appendage formation included positional changes, possibly affecting floral attributes and visitation by insects, rather than vertebrates. Nectar is released through three basal orifices distally on the ovary, and here we document the link between the nectary region, through discrete canals, upward to the conduplicate lobes of the wet stigma. Improved understanding of the floral development and morphology of Aechmea may help to explain the existence of polymorphic flowers in this genus and may have implications for studies on interactions with pollinators and systematics. [ABSTRACT FROM AUTHOR]

Leaf teeth are projections on the leaf blade margin. They are structurally variable, with characters that are important for taxonomy and phylogeny, but there is a paucity of information on the anatomy of these structures and little understanding of the features and their functions. Here we describe and compare the leaf tooth anatomy of 47 eudicot species. Toothed margin samples from leaves at different developmental stages were collected, fixed and studied under light and scanning electron microscopy. We identified eight leaf tooth morphotypes, six of which occurred with glands. Hydathodes were the most common glands, being found in 11 species; colleters were found in ten species and extrafloral nectaries were found in two species. Cunonioid teeth either devoid of glands or associated with hydathodes were found in Lamiales, Asterales and Apiales. Dillenioid teeth associated with hydathodes were found in Dilleniales. Spinose teeth associated with colleters were found in Aquifoliales. In rosids, we found begonioid, malvoid, theoid, urticoid and violoid teeth, which may be associated with either colleters or nectaries or lack an associated gland. For each family studied, there was only one type of association between gland and tooth, demonstrating the systematic potential of these glands in eudicots. [ABSTRACT FROM AUTHOR]

Nectar production dynamics can show inter- and intraspecific variation, which can be associated with environmental and ecological factors and with the ultrastructural diversity of the floral nectary. In this context, we recorded nectar production dynamics from a morphofunctional perspective using the hummingbird-pollinated Billbergia distachia (Bromeliaceae). The scale-throated hermit Phaethornis eurynome was the only floral visitor observed, indicating a specialized pollination system. Nectar production showed significant differences between day and night, and the periods of major pollinator activity and nectar secretion were synchronous. The ultrastructural features of the nectary showed some evidence of nectar reabsorption in flowers at night, and it can be inferred that this process may be a key factor in the nocturnal pause in nectar production. In this way, nectary morphoanatomy, nectar traits and an energy-saving mechanism through nectar reabsorption contribute to the well-established relationship between B. distachia and P. eurynome. [ABSTRACT FROM AUTHOR]

The flowers of most Anacardiaceae have a floral nectary disk producing nectar rich in sugars. However, a recent study demonstrated that their nectaries might also produce other substances, including lipids and phenolic compounds. To explore the diversity of floral nectary production and (ultra)structure, and their potential for the systematics of Anacardiaceae, we studied seven genera and 13 species from the two subfamilies. We used spectrophotometry to identify sugars and histochemical tests for other substances, and electron and brightfield microscopy to study nectary (ultra)structure and secretory pathways. The composition of sugars and other substances can vary between closely related species and be more similar in species from different subfamilies, being of limited value for the systematics of the family. The general morphology and structure of the floral nectary and their secretory pathways appear to be conservative in the family, and, like the production of mixed secretions, they might be plesiomorphic. Three morphological types of floral nectaries are defined for the family: nectariferous disk with papillose (1) or smooth epidermis-type (2) and trichomatous-type (3). The secretions may be released both by granulocrine and eccrine mechanisms and exuded through nectarostomata or the cuticle. Further studies are needed to better understand their evolutionary and ecological implications in Anacardiaceae and other sapindalean lineages. [ABSTRACT FROM AUTHOR]

Extrafloral nectaries (EFNs) are particularly common in Fabaceae and their morphological diversity has proved taxonomically useful. However, their anatomy remains poorly investigated. In this study we analysed EFN anatomy in 12 species from ten genera of Fabaceae, using scanning electron microscopy and light microscopy. We found three main structural organizations of EFNs. (1) The 'embedded' EFNs (cryptic and externally non-visible) in Bauhinia forficata are secretory prickles in which nectar-secreting tissue is completely embedded within the prickle, representing a new kind of EFNs in plants. Among externally visible EFNs, (2) 'elevated' EFNs were found in seven species, including a Mimosa sp. belonging to a clade considered to lack EFNs, and (3) 'swollen-scar' EFNs derived from the abscission site of aborted buds were found in four species, including a new report in Galactia. In three species, we also found colleters anatomically similar to other colleters reported for Fabaceae. We discuss terminological issues in the (scarce) literature on EFN anatomy in Fabaceae, mainly due to incorrect interpretation of structures or misuse of existing terms. [ABSTRACT FROM AUTHOR]

The placement of Nartheciaceae within Dioscoreales is an unexpected result of molecular phylogenetics. Nartheciaceae generally differs from the rest of Dioscoreales in having less specialized flowers. Studies of this family are important to elucidate the evolutionary history of the order. Using scanning electron microscopy and light microscopy, we describe the details of the flower structure, initiation, and development in Metanarthecium, which is unique amongst Nartheciaceae in possessing both an almost superior ovary and septal nectaries. This is the first member of Dioscoreales for which all stages of organogenesis have been studied. Within Nartheciaceae, the presence/absence of septal nectaries and the position of the ovary are labile. The presence of post-genital fusion in the gynoecium correlates with the presence of septal nectaries. Septal nectary morphology is complicated in Metanarthecium, which raises the question of whether its floral structure (including superior ovary) is plesiomorphic within Dioscoreales. The septal nectaries of Metanarthecium show homoplastic similarity with those of Allium (Asparagales). The presence/absence of a compitum is probably variable at the infraspecific level in Metanarthecium as a result of alternative possibilities of post-genital fusion between ventral carpel margins. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 158, 1–18. [ABSTRACT FROM AUTHOR]