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CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / Objetivou-se com esta pesquisa avaliar diferentes tÃcnicas de superaÃÃo de dormÃncia, o comportamento germinativo sob condiÃÃes salinas e de dÃficit hÃdrico, o desenvolvimento de plÃntulas submetidas a diferentes potenciais de solutos com NaCl e relacionar as condiÃÃes estressantes com a mobilizaÃÃo de reservas cotiledonares em plÃntulas de copaÃba (Copaifera langsdorffii Desf.). Os tratamentos de superaÃÃo de dormÃncia constituÃram-se de imersÃes em Ãgua/24, 48 e 72 h; Ãgua quente, 50, 75 ÂC e fervente/10, 15 e 20 min, em H2SO4 (98,08)/15, 30 e 60 min e controle. Para as condiÃÃes estressantes, as sementes foram imersas em 100 mL de soluÃÃo de NaCl ou de PEG 6.000 com potenciais de solutos: [0,0 -0,2, -0,4, -0,6, -0,8 e -1,0 MPa]. Avaliaram-se a embebiÃÃo (durante 168 h), percentagem de germinaÃÃo (%G) Ãndice de velocidade de germinaÃÃo (IVG) e tempo mÃdio de germinaÃÃo (TMG). Para a mobilizaÃÃo das reservas, os tratamentos foram os mesmos potencias de solutos com NaCl. A semeadura foi em papel germitest e a germinaÃÃo em cÃmara do tipo BOD a 25 ÂC com fotoperÃodo de 12 horas, com cinco repetiÃÃes de 25 sementes por tratamento. Os estudos dos efeitos do NaCl nas plÃntulas de copaÃba fez-se em trÃs estÃdios de desenvolvimento: ED 1 (raiz com 5Â2 cm); ED 2 (emissÃo dos protÃfilos) e ED 3 (protÃfilos expandidos), Quinze plÃntulas por repetiÃÃo foram separadas em cotilÃdones e eixos embrionÃrios. Quantificaram-se a massa seca dos cotilÃdones e dos eixos embrionÃrios, os teores de lipÃdios, proteÃnas, amido, aÃÃcares solÃveis, aminoÃcidos e Ãons Na+, K+ e Cl-. Avaliaram-se as atividades das enzimas: lipase, liase do isocitrato, sintase do malato, α e β-amilases e fosforilase do amido nos cotilÃdones de plÃntulas cultivadas em Ãgua destilada e em soluÃÃes de NaCl com potenciais de solutos de 0,0, -0,4 e -0,8 MPa. A imersÃo das sementes de copaÃba em Ãcido sulfÃrico concentrado/60min à eficiente para embebiÃÃo e superaÃÃo da dormÃncia. O PEG 6.000 e o NaCl atrasam a embebiÃÃo. Nas condiÃÃes estressantes, o NaCl -1,0 MPa nÃo influencia no %G, mas, aumenta oIVG e reduz o TMG a partir do potencial de soluto de -0,6, MPa. O PEG reduz o %G a partir de -0,8 MPa com maior efeito no IVG e TMG, do que NaCl. Sementes de copaÃba possuem 42% de lipÃdios, principal reserva. O potencial de soluto de -0,8 MPa inibe a mobilizaÃÃo de reservas e aumenta os teores de Ãons Na+ e Cl- nos cotilÃdones e eixos embrionÃrios de sementes de copaÃba. A inibiÃÃo da mobilizaÃÃo das reservas causada pelo sal aumenta os teores de aÃÃcares solÃveis nos cotilÃdones e inibe o crescimento das plÃntulas. As sementes de copaÃba apresentam forte resistÃncia à entrada de Ãgua, a qual pode ser anulada com imersÃo em Ãcido sulfÃrico concentrado por 60 min. Para o %G, as sementes testadas sÃo tolerantes ao NaCl em -1,0 MPa e intolerantes ao PEG em potenciais de solutos equivalentes. A germinaÃÃo à menos sensÃvel ao NaCl do que a fase de plÃntula. O NaCl em potenciais de solutos abaixo de -0,4 MPa reduzem o crescimento e desenvolvimento inicial de plÃntulas de copaÃba. As atividades das enzimas do metabolismo dos lipÃdios e do amido sÃo inibidas com o aumento da salinidade. / The objective of this research was to evaluate different techniques for breaking dormancy, the germination under saline conditions and drought, the development of seedlings subjected to different potentials of solutes and NaCl stress conditions relate to the cotyledonary reserve mobilization in seedlings Copaifera langsdorffii. The treatments of over come consisted of immersion in water/24, 48 and 72 h, hot water, 50, 75 C and boiling water/10â, 15â and 20â and H2SO4 (98,08%)/15, 30â and 60â min and control. For stress conditions, the seeds were immersed in 100 ml of NaCl or PEG 6000 with a potential of the solute, [0,0 (control), -0,2, -0,4, -0,6, -0,8 and -1,0 MPa]. The water absorption, was evaluated (168 h) germination percentage (G%), germination speed index (GSI) and mean germination time (MGT). For the mobilization of the reserves were used as the same solute potential with NaCl above. Sowing was on paper germitest and germination in a germination chamber of the BOD at 25 ÂC and photoperiod of 12 h, consisting of five replicates of 25 seeds per treatment. Studies of the effects of NaCl was done in three stages of developing an ED (radicle with 5  2 cm) ED 2 (issuing protophilus) and ED 3 (protophilus expanded), taking as reference quiescent seeds (DE 0). 15 seedlings per replicate were separated into cotyledons and axis. Quantified the dry mass of cotyledons and axis, the levels of lipids, proteins, starch, soluble sugars, amino acids and Na+, K+ and Cl-. We evaluated the activities of enzymes: lipase, the isocitrate lyase, malate synthase, α and β-amylases and starch phosphorylase in the cotyledons of seedlings grown in distilled water and in NaCl solutions with solute potential of -0,4 and -0,8 MPa. The water absorption by seeds copaiba was higher and faster in the treatments with boiling water and sulfuric acid. The PEG 6000 and NaCl delayed the time of soaking, Overall, the immersion in H2SO4 performed best in breaking dormancy. In stressful conditions, NaCl had no influence on %G, however, reduced the (IVG) and increased the TMG, the solute potential of -0,6, -0,8 and -1,0 MPa. PEG reduced the %G in solute potential of -0,8 and -1,0 MPa and had a greater effect on IVG and TMG, compared with NaCl. The seeds were quiescent lipids as the main reserve. The increase in salinity inhibited the mobilization of reserves in the cotyledons of the seeds, especially in the solute potential of -0,8 and -1,0 MPa and increasing the concentrations of Na+ and Cl- in the embryonic axis and cotyledons. Inhibition of the mobilization of reserves caused by salt provided an increase in soluble sugars in the cotyledons, this effect inhibited the growth and seedling development. The activities of enzymes in the metabolism of lipids and of starch phosphorylase were significantly inhibited with increasing salinity, with more effectively inhibited the enzymes of lipid metabolism. The seeds have a strong resist entry of water, the immersion of the seed in concentrated sulfuric acid for 60â is effective to remove the barrier. For %G, the copaiba seeds under conditions that were tested are NaCl-tolerant and intolerant to PEG. The germination is less sensitive than the NaCl seedling stage. The NaCl in solute potential below -0,4 MPa negatively affects the growth and early development of seedlings of copaiba

Submitted by Marco Antônio de Ramos Chagas (mchagas@ufv.br) on 2015-11-19T07:57:54Z No. of bitstreams: 1 texto completo.pdf: 1734373 bytes, checksum: 8f0e61ffd7c618f32dd451c1436c7495 (MD5) / Made available in DSpace on 2015-11-19T07:57:54Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1734373 bytes, checksum: 8f0e61ffd7c618f32dd451c1436c7495 (MD5) Previous issue date: 2015-02-26 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Chamaecrista Moench (Leguminosae, Caesalpinioideae, Cassieae, Cassiineae) inclui mais de 330 espécies. A presença de estruturas secretoras é um dos parâmetros utilizados para a circunscrição das seis seções do gênero, no entanto, tal circunscrição não é corroborada pelos estudos filogenéticos. A anatomia foliar de Chamaecrista tem se mostrado uma importante ferramenta, corroborando inclusive as novas circunscrições taxonômicas baseadas em dados moleculares. Dentre as várias estruturas secretoras descritas para o gênero Chamaecrista, coléteres foram mencionados em algumas das espécies estudadas. Entretanto um estudo comparativo da diversidade e importância taxonômica dessas estruturas no gênero Chamaecrista ainda não foi realizado. Dentre as seções de Chamaecrista, poucos estudos têm investigado a seção Apoucouita que inclui espécies com glândulas no pecíolo/raque e no racemo denominadas de nectários. No entanto, tal caracterização demanda estudos complementares como análise da presença de açúcar e análises histoquímicas. Embora estudos moleculares tenham se mostrado úteis para a separação e delimitação de grupos taxonômicos, caracteres morfológicos são necessários para reconhecimento das espécies tanto em campo quanto em herbário e nestes casos a morfoanatomia foliar é uma alternativa promissora. Os materiais foram processados conforme metodologia usual de microscopia de luz e varredura utilizados em estudos anatômicos. O trabalho foi organizado em três capítulos. No capítulo I a presença e a diversidade de coléteres em folhas e flores em desenvolvimento de espécies do gênero Chamaecrista, foram avaliadas. Foram descritos seis tipos de coléteres: “club-shaped”, “racket-shaped”, “long bottle-shaped”, “short bottle-shaped”, “long digitiform” e “short digitiform”. As análises histoquímicas confirmaram a presença de proteínas totais, polissacarídeos totais, mucilagens e lipídeos na secreção dos coléteres. O tipo e posição dos coléteres corroboram as novas circunscrições com base em estudos moleculares propostas para Chamaecrista. No capítulo II procedeu-se o estudo anatômico das glândulas do pecíolo/raque para verificar se tais estruturas correspondem a nectários como descrito na literatura. Foram observados 13 tipos de nectários extraflorais (NEF) para Chamaecrista, os quais podem ser impressos, sésseis ou pedunculados, com superfície secretora côncava, plano/truncada ou convexa. Embora variações morfológicas tenham sido observadas, a estrutura anatômica e a composição química da secreção foram similares para todos os tipos de NEF. A formação de periderme de cicatrização em NEFs mais velhos é um fato inédito para Chamaecrista, uma vez que não foi relatada para as outras seções do gênero. O capítulo III aborda a morfoanatomia das folhas de espécies de C. seção Apoucouita com vistas verificar a utilidade dessas características para fins taxonomicos. O arranjo do sistema vascular no pecíolo/raque, tipo de mesofilo, idioblastos mucilaginosos na face adaxial e abaxial da epiderme, contorno das paredes periclinais das células epidérmicas (reto na adaxial e sinuoso na abaxial) e posição e tipo de estômato, (hipoestomática e paracítico- laterocíclico, respectivamente) foram caracteres comuns a todas as espécies da seção Apoucouita. A presença e posição de papilas na epiderme e a posição e tipo de NEF são caracteres promissores quanto à taxonomia de algumas das espécies do gênero. / Chamaecrista Moench (Leguminosae, Caesalpinioideae, Cassieae, Cassiineae) includes more than 330 species. The presence of secretory structures is one of the parameters used for the circumscription of the six sections of the genus. However, such circumscription is not supported by the phylogenetic studies. Leaf anatomy of Chamaecrista has proved an important tool to the new taxonomic circumscription based on molecular data. Among the secretory structures described for Chamaecrista, colleters have been mentioned in some species. However, a comparative study of the diversity and taxonomic importance of such structures for Chamaecrista has not yet been performed. Among the sections of Chamaecrista, few studies have focused on sect. Apoucouita, a section with species displaying glands on the petiole/rachis and on the raceme. Such glands have been called extrafloral nectaries (EFN), even though, no additional studies such as the analysis of the presence of sugars and histochemical tests have been performed to confirm if such glands are in fact EFNs. Although molecular studies have proved useful in the circumscription of taxonomic groups, morphological characters are necessary for recognizing species in the field and also when dried material is analyzed and in both cases, leaf anatomy is a promising alternative for the recognition of species. For this study, standard anatomical techniques for light and scanning electron microscopy were carried out. The present study is organized in three chapters. The presence and diversity of colleters on developing leaves and flowers of Chamaecrista is described in Chapter I. Six types of colleters were described: “club- shaped”, “racket-shaped”, “long bottle-shaped”, “short bottle-shaped”, “long digitiform” and “short digitiform”. The histochemical analyses confirmed the presence of total proteins, total polysaccharides, mucilage and lipids in the secretion of the colleters. The type and position of colleter supported new circumscriptions based on molecular studies proposed for the Chamaecrista. The anatomical study of the petiole/rachis glands in order to verify if such structures are in fact nectaries, as described in the literature, is given in Chapter II. It was observed 13 types of ENFs for Chamaecrista. Such EFNs may be impressed, sessile or stalked, with secretory surface concave, flat/truncate or convex. Although morphological variations were observed, the anatomical structure and chemical composition of the secretion was similar to all types of EFNs. The formation of a wound-healing periderm in older EFNs is a novelty for Chamaecrista, as such was not reported for the other sections of the genus. The leaf morphoanatomy of C. sect. Apoucouita with the intent of using such characters in the taxonomy is given in Chapter III. The arrangement of the vascular system in the petiole/rachis, type of mesophyll, mucilage idioblasts in the adaxial and abaxial epidermis, outline of the anticlinal walls of the epidermal cells (straight on the adaxial side and sinuous on the abaxial side) and the position and type of stomata (hipostomatic leaves and paracytic laterocyclic, respectively) were characters common to all species from sect. Apoucouita. The presence of papillae on the epidermis as well as the position and type of extrafloral nectaries are promising characters regarding the taxonomy of some species of Chamaecrista.

Sixteen outbreaks of Senna occidentalis (coffee senna) occurring in cattle from the state of Rio Grande do Sul, Brazil, were reviewed. The great majority (75%) of the outbreaks occurred in adult cattle at pasture during the autumn and winter months with 50% occurring in May, evidencing a striking seasonality. Mortality rates varied from 4.2% to 55.2% and cattle died 2 days up to 2 weeks after showing clinical signs that included dry feces (occasionally diarrhea), muscle weakness, reluctance to move, tachypnea, instability of the hind limbs with dragging of the toes, tremors in muscles of the thighs, neck, and head, ear dropping, sternal recumbency, lateral recumbency and death. Myoglobinuria characterized by a dark red or black discolored urine was a consistent finding in cattle affected at pasture but not in those poisoned by ration contaminated with coffee senna beans. Creatine phosphokinase serum activity was markedly elevated. Main gross changes observed in 23 necropsies involved skeletal muscles of the hind limbs. These changes consisted of varying degrees of paleness of muscle groups. Subepicardial and subendocardial hemorrhages were present in the hearts of all affected cattle. Histologically a segmental degenerative myopathy of striated muscles was present in every case and had a multifocal polyphasic or monophasic character. Myocardial (3/23), hepatic (3/13), renal (3/10), and splenic (1/6) microscopic lesions were observed occasionally. Myocardial lesions were mild and consisted of vacuolation of cardiomyocytes or focal fibrosis. Hepatic changes consisted of diffuse hepatocellular vacuolation, cytosegrosomes within hepatocytes, and individual hepatocellular necrosis. Kidneys have vacuolar degeneration of tubular epithelium associated with acidophilic casts (proteinosis) within tubular lumina. In the spleen there was marked necrosis of lymphocytes of the white pulp. No histological changes were found in the brains of 13 affected cattle. The data of this study suggest that coffee senna poisoning is an important cause of death in cattle in southern Brazil. The epidemiological, clinical and pathological features described in the study shoud be useful for diagnosing the condition in the field. / Dezesseis surtos de intoxicação por Senna occidentalis (fedegoso) em bovinos do Rio Grande do sul foram revisados. A grande maioria dos surtos (75%) ocorreu em bovinos adultos em pastoreio durante o outono e inverno com 50% dos surtos ocorrendo em maio, evidenciando uma notável sazonalidade. Os coeficientes de mortalidade variaram de 4,2% a 55,2% e os bovinos morriam dois dias a duas semanas após mostrarem sinais clínicos que incluíam fezes ressecadas (ocasionalmente diarreia), fraqueza muscular, relutância em mover-se, taquipneia, instabilidade dos membros pélvicos com arrastamento das pinças, tremores nos músculos das coxas, pescoço e cabeça; orelhas caídas, decúbito esternal, decúbito lateral e morte. Mioglobinúria, caracterizada por urina vermelho-escura ou preta foi regularmente encontrada em bovinos afetados em pastoreio, mas não naqueles que se intoxicaram ingerindo ração contaminada com as sementes da planta. A atividade sérica da creatina fosfocinase estava acentuadamente elevada. As principais alterações macroscópicas observadas em 23 necropsias envolviam os músculos esqueléticos dos membros pélvicos. Essas alterações consistiam de graus variáveis de palidez em grupos musculares. Hemorragias subepicárdicas e subendocárdicas ocorreram nos corações de todos os bovinos afetados. Histologicamente, miopatia degenerativa dos músculos estriados esteve presente em todos os casos e tinha um caráter multifocal monofásico ou polifásico. Lesões microscópicas no miocárdio (3/23), fígado (3/13), rim (3/10) e baço (1/6) foram ocasionalmente observadas. As lesões miocárdicas eram discretas e consistiam de vacuolização dos cardiomiócitos ou fibrose focal. As lesões hepatocelulares consistiam de vacuolização difusa, formação de citossegrossomos e necrose individual. Nos rins havia degeneração vacuolar do epitélio tubular associada a cilindros eosinofílicos (proteinose) na luz tubular. No baço havia marcada necrose de linfócitos da polpa branca. Nenhuma alteração foi encontrada ao exame histológico do encéfalo de 13 bovinos afetados. Os dados deste estudo sugerem que a intoxicação por fedegoso é uma importante causa de morte em bovinos do sul do Brasil. Os aspectos epidemiológicos, clínicos e patológicos descritos neste estudo deverão ser úteis no diagnóstico a campo desta intoxicação.

Bauhinia s.l. est le plus vaste genre de la tribu des Cercideae (Ceasalpinioideae, Leguminoseae), avec plus de 300 espèces. Il présente une distribution pantropicale et une grande variabilité morphologique. Ces deux caractéristiques ont limité les études taxonomiques sur le genre complet, résultant en plusieurs études taxonomiques de certains groupes seulement. En 1987, Wunderlin et al. proposent une vaste révision taxonomique de la tribu des Cercideae, basée sur des données morphologiques, et divisent le genre Bauhinia en quatre sous-genres. En 2005, Lewis et Forest publient une nouvelle classification préliminaire basée sur des données moléculaires, mais sur un échantillonnage taxonomique restreint. Leurs conclusions remettent en question le monophylétisme du genre Bauhinia et suggèrent plutôt la reconnaissance de huit genres au sein du grade Bauhinia s.l. Afin de vérifier les hypothèses de Lewis et Forest, et obtenir une vision plus claire de l’histroire de Bauhinia s.l., nous avons séquencé deux régions chloroplastiques (trnL-trnF et matK-trnK) et deux régions nucléaires (Leafy et Legcyc) pour un vaste échantillonnage représentatif des Cercideae. Une première phylogénie de la tribu a tout d’abord été réalisée à partir des séquences de trnL-trnF seulement et a confirmé le non-monoplylétisme de Bauhinia s.l., avec l’inclusion du genre Brenierea, traditionnellement reconnu comme genre frère de Bauhinia s.l. Afin de ne pas limiter notre vision de l’histoire évolutive des Cercideae à un seul type de données moléculaires et à une seule région, une nouvelle série d’analyse a été effectuée, incluant toutes les séquences chloroplastiques et nucléaires. Une phylogénie individuelle a été reconstruite pour chacune des régions du génome, et un arbre d’espèce ainsi qu’un arbre de supermatrice ont été reconstruits. Bien que certaines contradictions apparaissent entre les phylogénies, les grandes lignes de l’histoire des Cercideae ont été résolues. Bauhinia s.l. est divisée en deux lignées : les groupes Phanera et Bauhinia. Le groupe Bauhinia est constitué des genres Bauhinia s.s., Piliostigma et Brenierea. Le groupe Phanera est constitué des genres Gigasiphon, Tylosema, Lysiphyllum, Barklya, Phanera et Schnella. Les genres Cercis, Adenolobus et Griffonia sont les groupes-frères du clade Bauhinia s.l. Au minimum un événement de duplication de Legcyc a été mis en évidence pour la totalité de la tribu des Cercideae, excepté Cercis, mais plusieurs évènements sont suggérés à la fois par Legcyc et Leafy. Finalement, la datation et la reconstruction des aires ancestrales de la tribu ont été effectuées. La tribu est datée de 49,7 Ma et est originaire des régions tempérées de l’hémisphère nord, probablement autour de la mer de Thétys. La tribu s’est ensuite dispersée vers les régions tropicales sèches de l’Afrique, où la séparation des groupes Bauhinia et Phanera a eu lieu. Ces deux groupes se sont ensuite dispersés en parallèle vers l’Asie du sud-est au début du Miocène. À la même période, une dispersion depuis l’Afrique de Bauhinia s.s. a permis la diversification des espèces américaines de ce genre, alors que le genre Schnella (seul genre américain du groupe Phanera) est passé par l’Australie afin de rejoindre le continent américain. Cette dispersion vers l’Australie sera également à l’origine des genres Lysiphyllum et Barklya / Bauhinia s.l. is the largest genus of the tribe Cercideae (Ceasalpinioideae, Leguminoseae), with over 300 species. It has a pantropical distribution and high morphological variability. These two features have resulted in few studies that focus on the entire genus, resulting in several regional studies or studies of certain subgroups only. In 1987, Wunderlin et al. presented a broad taxonomic revision of the tribe Cercideae, based on morphological data, and divided the genus Bauhinia into four subgenera. In 2005, Lewis and Forest published a new preliminary classification based on molecular data, but for a limited taxonomic sampling. Their findings question the monophyly of the genus Bauhinia and suggest instead the recognition of eight genera in the Bauhinia s.l. grade. To test the hypotheses of Lewis and Forest, and to obtain a clearer view of the history of Bauhinia s.l., we sequenced two chloroplast regions (trnL-trnF and matK-trnK) and two nuclear regions (Leafy and Legcyc) for a large representative sampling of the Cercideae. A primary phylogeny of the tribe was first generated based on trnL-trnF sequences only and confirmed the non-monophyly of Bauhinia s.l., with the inclusion of the genus Brenierea, traditionally recognized as sister group of Bauhinia s.l. In order to obtain a deaper view of the evolutionary history of the Cercideae, a new series of analysis was performed, including all nuclear and chloroplast sequences. Individual phylogenies were reconstructed for each region of the genome, and both a species and a supermatrix trees were reconstructed. Although certain conflicting relationships appear between phylogenies, the outline of the history of the Cercideae has been resolved. Bauhinia s.l. is divided into two lineages: Phanera and Bauhinia groups. The Bauhinia group includes Bauhinia s.s., Piliostigma and Brenierea. The Phanera group is composed of Gigasiphon, Tylosema, Lysiphyllum, Barklya, Phanera and Schnella. Cercis, Griffonia and Adenolobus are sister groups of Bauhinia s.l. At least one duplication event of Legcyc has been highlighted for the entire tribe Cercideae, excluding Cercis. Several other duplication events are also suggested by both Legcyc and Leafy . Finally, a divergence time analysis and a reconstruction of ancestral areas were conducted. The root of the tribe is evaluated to be 49.7 Mya old, and to originate from temperate regions in the northern hemisphere, mostly around the Tethys Sea. The tribe then dispersed into drier biomes in Africa, where the separation of the Bauhinia and the Phanera groups occurred. These two lineages then dispersed following parallel routes to Southeast Asia in the early Miocene. At the same time, a dispersal of the African Bauhinia s.s. to South America permitted the diversification of the American species of this genus, and Schnella (the only American genus within the Phanera group) dispersed to the American continent from Australia. This dispersal to Australia is also at the origin of Lysiphyllum and Barklya.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Le clade Dialiinae représente l’une des premières lignées de la sous-famille Caesalpinioideae des Leguminosae. Il se compose de 17 genres (environ 90 espèces), avec des taxons qui sont répandus dans toutes les régions tropicales du monde. Morphologiquement, le groupe comprend un assemblage divers de taxons qui peut représenter une «phase expérimentale» dans l’évolution florale des légumineuses. Différents représentants du clade présentent de la poly-, mono-, et asymétrie, et semblent avoir subi un haut degré de perte d’organe, produisant, dans certains cas, des fleurs extrêmement réduites qui sont à peine reconnaissables comme appartenant à la famille des légumineuses. Afin d’obtenir une image plus claire de l’évolution florale du clade Dialiinae, une phylogénie bien résolue et bien soutenue est nécessaire. Dans le but de créer une telle phylogénie, un total de 37 échantillons d’ADN des Dialiinae a été séquencé pour deux régions chloroplastiques, soit rps16 et trnL. De plus, une étude morphologique complète a été réalisée. Un total de 135 caractères végétatifs et reproductifs a été évalué pour 79 espèces de Dialiinae et pour quatre groupes externes. Les analyses phylogénétiques ont d’abord été effectuées sur un groupe restreint de taxons pour lesquels les trois types de données étaient disponibles. Les nœuds fortement soutenus de cette phylogénie ont ensuite été utilisés comme contrainte pour une seconde analyse de parcimonie avec les données morphologiques d’un ensemble plus important de taxons. Les caractères morphologiques ont été optimisés sur l’un des arbres les plus parcimonieux de cette seconde analyse. Un certain nombre de nouvelles relations au niveau de l’espèce ont été résolues, créant une image plus claire quant à l’évolution de la forme florale dans le temps, particulièrement pour les genres Labichea et Dialium. En plus de leur morphologie florale mature diverse, les Dialiinae sont également très variables dans leur ontogénèse florale, affichant à la fois la perte et la suppression des organes, et présentant une variété de modes d’initiation d’organes. Afin de construire une image plus complète du développement floral et de l’évolution dans ce clade, l’ontogénèse florale de plusieurs espèces non documentées à ce jour a été étudiée. La série complète du développement a été compilée pour six espèces de Dialiinae; quatre de Dialium, ainsi que Poeppigia procera et Mendoravia dumaziana. Le mode et le moment de l’initiation des organes étaient pour la plupart uniforme pour toutes les espèces de Dialium étudiés. Tant pour ce qui est des gains ou des pertes d’organes chez Dialium, une tendance est apparente – l’absence d’organe abaxial. Que ce soit pour les sépales ou les étamines, les gains se produisent toujours en position médiane adaxiale, tandis que les étamines et les pétales perdus sont toujours les organes les plus ventraux. Les taxons étudiés ici illustrent le manque apparent de canalisation du développement observé chez les Caesalpinioideae. Cette plasticité ontogénétique est le reflet de la diversité morphologique au niveau des fleurs tel qu’observée dans l’ensemble de la sous-famille. Une des espèces de Dialiinae, Apuleia leiocarpa, produit une inflorescence andromonoïque, une caractéristique qui est unique en son clade et rare dans les légumineuses dans son ensemble. La microscopie optique et électronique ont été utilisées pour entreprendre une étude détaillée de la morphologie florale de ce taxon. On a constaté que tandis que les fleurs hermaphrodites produisent un seul carpelle et deux étamines, les fleurs staminées produisent trois étamines sans toutefois montrer signe de développement du carpelle. Les inflorescences semblent produire près de quatre fois plus de fleurs staminées que de fleurs hermaphrodites, lesquelles occupent toujours la position centrale de l’inflorescence cymeuse. Ce ratio élevé mâle/bisexuel et la détermination précoce du sexe chez Apuleia sont rares chez les Caesalpinioideae, ce qui suggère que l’andromonoecie se développe dans ce genre comme un moyen d’accroître la dispersion du pollen plutôt qu’en réponse à des limitations de ressources. / The Dialiinae clade represents one of the early-diverging lineages of the legume subfamily Caesalpinioideae; it consists of 17 genera (circa 90 species), and is pantropically distributed. Morphologically, the group comprises a diverse assemblage of taxa that may represent a so-called “experimental phase” in legume floral evolution. Different members of the clade exhibit poly-, mono-, and asymmetry, as well as having undergone a high degree of organ loss, producing, in some cases, extremely reduced flowers which are barely recognisable as belonging to the legume family. In order to obtain a clearer picture of floral evolution in the Dialiinae, a well resolved and well supported phylogeny is needed onto which morphological characters may be optimised. With the goal of creating such a phylogeny, a total of 37 Dialiinae DNA samples were sequenced for two plastid genes, rpS16 and trnL. Additionally, a comprehensive morphological study was carried out. A total of 135 vegetative and reproductive characters were scored for 79 ingroup and four outgroup taxa. Phylogenetic analyses were carried out first on a restricted group of taxa for which all three data sets were available. The highly supported nodes of this phylogeny were then used as a constraint for a second parsimony analysis of morphological data from a much larger taxon set. Morphological characters were then mapped onto one of 20,000 most parsimonious trees from this second analysis. A number of novel species-level relationships were resolved, creating a clearer picture of changes in floral form over time, particularly in the genera Labichea and Dialium. In addition to their diverse mature floral morphology, the Dialiinae are also widely variable in their floral ontogeny, displaying both organ loss and suppression, and exhibiting a wide variety of organ initiation modes. In order to build a more complete picture of floral development and evolution in this clade, the floral ontogeny of several previously undocumented species was investigated. Complete developmental series were compiled for six species of the Dialiinae; four from Dialium, as well as Poeppigia procera and Mendoravia dumaziana. Mode and timing of organ initiation were mostly consistent across the Dialium species studied. In the instances of both gains and losses of floral organs in Dialium, one trend is apparent — an absence of abaxial organs. Gains in both sepals and stamens occur in the adaxial median position, while stamens and petals that are lost are always the ventral-most organs. The taxa examined here exemplify the apparent lack of developmental canalisation seen in caesalpinioid legumes. This ontogenetic evolvability is reflective of the morphological diversity shown by flowers across the subfamily. One of the species of the Dialiinae, Apuleia leiocarpa, produces an andromonoecious inflorescence, a feature that is unique in its clade and rare in the Leguminosae as a whole. Light and electron microscopy were used to undertake a detailed study of the floral morphology of this taxon. It was found that while hermaphrodite flowers produced a single carpel and two stamens, staminate flowers developed three stamens but showed no sign of carpel development. Inflorescences also appear to produce approximately four times as many staminate as hermaphrodite flowers, with hermaphroditic flowers consistently occupying the central position in cymose inflorescences. Both this high male-to-bisexual ratio and the early determination of gender seen in Apuleia are rare in the Caesalpinioideae and suggest that andromonoecy developed in this genus as a means to increase pollen dispersal rather than in response to resource limitations.