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Xyridaceae are represented in New Caledonia only by the genus Xyris , the description of which was last revised in the 1960s, and three endemic species were recognized there at that time, X. pancheri , X. neocaledonica and X. guillauminii. However, no specimens of X. guillauminii were reported from P or L, although some type material was present. In addition, most material was unidentified at the species level in international herbaria (up to 45% for the NOU herbarium), showing that the family had not been studied in the framework of the Flore de la Nouvelle-Calédonie. In total, 129 herbarium specimens were examined for an ascendant hierarchical classification and a principal coordinates analysis based on 18 morphological characters regarded as diagnostic at the species level (including six used in the original revision). The analyses revealed three well-delimited groups that potentially correspond to species-level units. A sub-sampling of 21 specimens, representative of these three groups, was studied anatomically (leaf cross-sections) and by scanning electron microscopy (leaf surface and seeds) and provided ten additional characters. This additional dataset validated the taxonomy in three species-level units. The resulting entities were then compared with nomenclatural types, which showed that the first corresponded to X. neocaledonica , the second represents a well-delimited, undescribed species, and the third includes types of both X. pancheri and X. guillauminii , this last being in need of synonymization. The findings of the present study provide a basis for undertaking a taxonomic revision of Xyris in New Caledonia, including the description of the new species. All New Caledonian species have an axile placentation and a trilocular ovary, so they belong to Xyris section Pomatoxyris , which is no longer endemic to Australia. [ABSTRACT FROM AUTHOR]

Subtribe Eleusininae (Chloridoideae, Poaceae) comprise 237 species with little morphological diversity in inflorescence structure. This diversity may be explained by an evolution from complex (pyramidal, highly branched) to simpler (digitate, barely branched) morphologies. However, only mature specimens have been studied; the developmental analyses of the inflorescences are rare. We analysed the inflorescence, spikelet and flower development of 17 species of Eleusininae using scanning electron microscopy. In the early stages of the transition to flowering of the studied species, the inflorescence meristem elongates initiating primary branches acropetally. The differentiation of these branches along the main axis is either basipetal or amphipetal. Although the initiation of secondary branches along primary branches may be acropetal or amphipetal, their differentiation follows an amphipetal direction. The florets in spikelets are initiated acropetally. We found abnormal orientation of stamens and gynoecium in florets of Leptochloa chloridiformis. The analysis of the ontogeny has enriched current knowledge of inflorescences in the subtribe. In addition, the developmental patterns revealed the existence of more than one developmental pattern leading to similar mature inflorescence forms. The results will support future efforts on postulating trends of developmental patterns across Poaceae. [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]

Anarthria, Lyginia and Hopkinsia, endemic to south-western Western Australia, differ from the rest of Restionaceae sensu APG IV in the presence of dithecal rather than monothecal anthers. Dithecal and monothecal Restionaceae form two well-supported sister clades in molecular phylogenetic trees, but shared morphological features of Anarthria, Lyginia and Hopkinsia known so far are either symplesiomorphies (e.g. anther structure) or are characters that are homoplastic in monocots (e.g. absence of silica in culms). The taxonomic placement of the three genera has been controversial during the 20th century, including the idea of recognizing three monogeneric families. As comparative morphological data covering all three genera are limited, we provide a study of female flower structure and development in this group. This is the first developmental study of dithecal Restionaceae that uses scanning electron microscopy. With many more investigated characters, like earlier studies, we found no potential synapomorphies for the dithecal clade. However, we found the first morphological support for the conclusion from molecular data of a sister relationship between Hopkinsia and Lyginia. They share ovules with length not exceeding the width and the micropyle oriented towards the dorsal side of the carpel, which is probably a synapomorphy. Some other characters shared by the two genera could be plesiomorphic, such as inner whorl tepals that are shorter than the gynoecium throughout development. Contrary to some earlier reports, female flowers of all three genera are arranged in spikelets and do not have bracteoles. These characters are thus conserved across the restiid and graminid clades. The gynoecium of Hopkinsia is unicarpellate and not pseudomonomerous. Gynoecia with a single fertile ovule appeared several times and through different morphological pathways in the evolution of wind-pollinated Poales. [ABSTRACT FROM AUTHOR]

Inflorescence morphology in Poaceae subtribes Hilariinae, Monanthochloinae, Boutelouinae, Scleropogoninae and Muhlenbergiinae (Cynodonteae, Chloridoideae) has been revisited recently, but inflorescence development remains largely unexplored. The aim of this study is to contribute additional information on the development of inflorescences in Cynodonteae by generating data on Distichlis, Bouteloua, Munroa, Erioneuron and Muhlenbergia and to compare them with results for other grasses. Using scanning electron microscopy images, we identified common developmental patterns among grasses and described developmental novelties for Bouteloua, Distichlis and Muhlenbergia. Novel developmental features are: the amphipetal initiation of second-order branches along the inflorescence of B. curtipendula, the elongation of the internodes of the inflorescence branches before floral development in M. asperifolius and 'Type II' unisexual flowers in D. acerosa. Variable traits among studied species are: inflorescence symmetry, direction of branch and spikelet initiation and differentiation, number of developing stamens, glume developmental patterns and timing of the arrest of gynoecium development during the formation of unisexual flowers. Our results allow us to postulate that a delicate balance of phytohormones may direct early development of grass inflorescence branching system by controlling direction of first-order branch differentiation. The approach used here provides a link between definitive structures and the underlying genetics. [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]

Tillandsioideae are composed of nine genera, most of these with unclear delimitation. The morphoanatomy of ovules and ovaries of 83 species from seven different genera was studied under light or scanning electron microscopy to contribute to the understanding of the relationships in the group. The nucellar epidermis and the parietal tissue showed a regular pattern for all Tillandsioideae. The presence of chalazal appendages, however, and their shape and size varied between the genera analysed. Most species had a single acuminate chalazal appendage. Catopsis was the only genus with multiple appendages. Guzmania and Racinaea lacked this structure. The integuments also presented a variable length and thickness among the different genera. The four to six layers of the outer integument were unique in Catopsis and the three cell layers condition in the inner integument of Tillandsia should be a retained feature as it was also observed in Catopsis. Many characteristics in ovule morphology presented here have great systematic value for distinguishing genera of the Tillandsioideae. In addition, these features can also help in the understanding of ovule evolution in Bromeliaceae as a whole. [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]