M.M. Alemán’s research while affiliated with National University of Salta and other places

Several floral traits in Papilionoideae (Fabaceae) have been correlated to certain pollination mechanisms. To test this hypothesis, we analyzed 20 qualitative and 21 quantitative floral traits of 17 species of Papilionoideae with keel flowers from various tribes and genera native to Salta, Argentina, which are representative of the four general pollination mechanisms described for the subfamily. We performed field and laboratory studies, including description of morphology, micro-morphology, position, size, and synorganization of all floral organs. Correlation between floral traits and a particular pollination mechanism was evaluated through a principal component analysis (PCA). According to our results, species with the same pollination mechanism share similar qualitative and quantitative traits, the latter being the most relevant, according to our statistical analysis.

Introducción y objetivos: Las especies de Papilionoideae presentan características florales o estrategias relacionadas con los mecanismos de polinización y que favorecen la polinización cruzada como la presencia de barreras físicas, la separación espacial o temporal en la maduración de los ciclos fértiles, entre otras. El objetivo de este trabajo fue brindar una descripción detallada de la morfología del androceo y gineceo de 17 especies de Papilionoideae nativas del Valle de Lerma (Salta-Argentina). M&M: Se estudiaron a campo y en laboratorio características cuantitativas y cualitativas del androceo y el gineceo en flores de 17 especies de Papilionoideae, pertenecientes a nueve géneros y cinco tribus y se analizaron desde un punto de vista funcional aquellas características que estarían relacionadas con el sistema reproductivo y los mecanismos de polinización. Resultados: Los resultados indican que la mayoría de las especies son homógamas, presentan androceo monadelfo o pseudomonadelfo con fenestras basales, anteras monomórficas, formas variables del estilo y del estigma, tricomas estilares y periestigmáticos y membrana estigmática. Se registraron características descritas por primera vez para algunas de estas especies tales como la ruptura espontánea de la membrana estigmática durante la antesis y la reducción de la distancia anteras-estigma luego de la maduración de los ciclos sexuales. Conclusiones: Todas las especies estudiadas presentan características florales asociadas a la reducción de la autopolinización. Se obtuvo información detallada sobre la morfología y otras características del androceo y gineceo que podría ser utilizada para describir mejor sus mecanismos de polinización y para comprender aspectos de su biología reproductiva.

The species of subfamily Papilionoideae present flowers with a complex architecture, with elaborated petals in which it has been documented the presence of auricles and callosities, appendixes or spurs that joint the pieces of the corolla and also microsculpturings on the wings. In this study, we analyze the morphology of the petals of 17 species of Papilionoideae (Leguminosae) native of Salta province, Argentina. The lower margins of the keel were fused in all of the species, through different types of fusion of epidermal cells. Only a few species presented fusion in the upper margin of the keel. All the species showed sculpturings in the petals, which would joint some of the pieces of the corolla. They also exhibit ornaments or microsculpturings in the basal region of the adaxial surface of the wings that may act as a grip for pollinators when they land on the flower. The petals of the Papilionoideae flowers presented characteristics that could restrict the type of pollinator able to activate the different mechanisms of pollination that allow them to access the rewards enclosed by the keel.

In the papilionaceous flowers with explosive pollination mechanism, the androecium and the gynoecium are subjected to great pressure in the keel. It has been suggested that at the first visit nearly all pollen grains are released and that the floral parts do not return to their original positions; this would be a cue for pollinators to avoid activated flowers. The dependence on the pollinators suggests that explosive flowers will not produce fruits if the mechanism is not activated. In this paper, we have tested these ideas studying the reproductive biology of three Desmodium species, D. incanum, D. subsericium and D. uncinatum. Specifically, we studied the floral traits, reproductive system, pollination mechanism and floral visitors, for the three species. The results indicated that the keel and the wings play a key role in the activation of the explosive mechanism. The three species have a secondary pollen presentation, diurnal flowers, and a short floral cycle. According to the results, all the species studied were self-compatible, with two species producing fruits by autonomous self-pollination. Desmodium flowers were visited and activated by native and exotic bee species. During the first visit nearly all the pollen was released; after that, new visits were low or null. Our results indicated that the activation of the mechanism is not essential for the production of fruits, that explosive flowers are visited only once and that the changes in the positions of the floral parts are the cues that keep pollinators away from the flowers with activated mechanism.

Plants in the genus Erythrina are pollinated by birds, such that passerine pollination is the plesiomorphic state, whereas hummingbird pollination is the derived character. Phylogenetic studies suggest that Erythrina dominguezii belongs to a basal clade characterised as pollinated by both passerines and hummingbirds. Here, we characterise the pollination system of E. dominguezii. Floral morphology, nectar traits, breeding system, visitation rates and pollen deposition by its floral visitors were studied. Floral morphology of E. dominguezii showed traits associated with both passerine and hummingbird pollination. Nectar sugar concentration showed an intermediate value but closer to the hummingbird type; however, it was rich in hexose, which is typical of the passerine type. Approximately 5% of the flowers set fruits under free pollination. Almost 80% of recorded flowers were visited by birds, with the rest visited by hymenopterans (bumblebees and honeybees). Among avian pollinators, five species of hummingbirds and three passerine species were identified as pollinators. The hummingbird Chlorostilbon lucidus was the most efficient visitor in terms of pollen deposition and was second in frequency of visits. The passerine Icterus cayanensis was second in efficiency at depositing pollen and was the most frequent pollinator. Our results show that E. dominguezii has a generalised pollination system. In addition, we report a new case of closed flowers and secondary nectar presentation. This is the first study that compares effectiveness among different pollinators in Erythrina.

Argentina is one of the most diverse countries in the world due to its species richness and endemism. A survey was carried out to categorize medicinal Angiosperms weeds found in Salta Province. We found that Dicotyledones constitutes 92.1%, with 65 families and 232 genera. Asteraceae turned out to be the family with the largest number of used taxa (24.55% of the total medicinal plants), followed by Fabaceae (9.02%), Solanaceae (7.67%), Verbenaceae (6.65%) and Lamiaceae (5.63%). Monocotyledones are represented by 10 families and 26 genera. The most important families were Poaceae (4.16% of the total medicinal plants), Typhaceae (1.04%), Liliaceae (0.52%) and Cannaceae (0.52%). The recorded species were associated with 33 health problems. Considering the most common medicinal uses we recorded that 17% of the species had an antibiotic activity, 9.32% of the species had antifungal activity, and 7.6% had anti-inflammatory activity. The most frequently used plant part were leaves (25.6%), stems (15.9%) and roots (10.6%). These taxa are still used for the prevention and relief of medical disorders. The number of species covered in this review demonstrates that Salta Province represents an important source of medicinal plants.

Plants in the genus Erythrina are pollinated by birds, such that passerine pollination is the plesiomorphic state, whereas hummingbird pollination is the derived character. Phylogenetic studies suggest that Erythrina dominguezii belongs to a basal clade characterised as pollinated by both passerines and hummingbirds. Here, we characterise the pollination system of E. dominguezii. Floral morphology, nectar traits, breeding system, visitation rates and pollen deposition by its oral visitors were studied. Floral morphology of E. dominguezii showed traits associated with both passerine and hummingbird pollination. Nectar sugar concentration showed an intermediate value but closer to the hummingbird type; however, it was rich in hexose, which is typical of the passerine type. Approximately 5% of the owers set fruits under free pollination. Almost 80% of recorded owers were visited by birds, with the rest visited by hymenopterans (bumblebees and honeybees). Among avian pollinators, ve species of hummingbirds and three passerine species were identied as pollinators. The hummingbird Chlorostilbon lucidus was the most efcient visitor in terms of pollen deposition and was second in frequency of visits. The passerine Icterus cayanensis was second in efciency at depositing pollen and was the most frequent pollinator. Our results show that E. dominguezii has a generalised pollination system. In addition, we report a new case of closed owers and secondary nectar presentation. This is the rst study that compares effectiveness among different pollinators in Erythrina.

The pollen:ovule ratio (P/O) has traditionally been used as a rough estimator of plant breeding systems. It has been shown that plant breeding systems are associated with particular floral traits. In this study, we determined the P/O in 21 Leguminosae species from Argentina and explored relationships between P/O and taxonomic position, flower size, floral rewards, pollen presentation and pollination mechanisms. According to the results, 15 out of the 21 species classified were obligate xenogamous, although some of them have been recorded as facultative xenogamous in previous studies. There was a significant effect of taxonomic position (genus), reward type and pollination mechanism on P/O. Species offering only nectar as a floral reward (which were species with a brush mechanism) had a significantly lower P/O than species offering pollen or pollen and nectar. Species with the brush pollination mechanism had the lowest P/O, while species with valvular and pump mechanism had the highest P/O. However, pollen presentation (primary and secondary) and flower size did not have a significant effect on P/O. Our results demonstrate that P/O variability is determined by taxonomic position and pollination mechanism in this plant group.

We studied the growth habit and root anatomy on two species of the Macroptilium genera, Fabaceae. These species, potential forages, are native to the Northwest Provinces in Argentina. The aims of this paper were to determine the survival capacity of the study species relating its growth habit and persistence with morphological and anatomical features. Root samples were collected and cut using either a microtome or by hand, at varying distances from the root tip. Cuts were examined under a light microscope, and with scanning electron microscopy (SEM) using staining techniques. Macroptilium bracteatum and M. erythroloma are perennial herbs. Aerial parts die during winter, and sprouting occurs in spring from the innovation area, throughout sub-superficial buds. In addition, M. bracteatum and M. erythroloma develop root succulence as a strategy of persistence. Besides, M. bracteatum presents endogenous root buds arising from one-year-old roots with secondary growth. These results indicate that both Macroptilium bracteatum and M. erythroloma have good potential as forage species.