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The aims of the present study were (i) to compare the anatomical structures of roots from legume species belonging to the tribes Aeschynomeneae, Fabeae (syn. Vicieae), and Trifolieae (Papilionoideae); (ii) to characterize those developmental stages of roots that are most useful for comparative studies; (iii) to characterize root developmental patterns during their growth from primary to adult structures; and (iv) to identify developmental patterns that are typical for particular tribes within this plant group. To this end, serial transverse cuts of the main roots of 20 species belonging to the above-mentioned tribes were made from the root tip to the root collar. Vessel density, vessel diameter, secondary cortex area, and xylem area were quantified using appropriate software. Based on root ontogeny, four stages giving evidence for important developmental events were chosen based on which a comparison of the species-specific structures became possible. The first stage corresponds to the primary structure of a root. The second stage corresponds to the onset of cambium and phellogen division, when their first division products become differentiated. The third and fourth stages correspond to adult roots with a well-developed secondary structure. These developmental stages that allowed between-species comparison turned out to be useful characterising those patterns that best typify a particular tribe within the subfamily. Vessel density, vessel diameter, and the xylem transverse area were found to differ significantly between the tribes examined. Some of the analyzed morphological variables had a tribe-specific consistency, so that, together with other characteristics, they should be included in approaches to clarify systematic problems in the legume family.

Hoffmannseggia glauca is a perennial weed that has tubers and root-borne buds. Some authors only consider root tubers without mentioning root-borne buds, while others consider that more anatomic studies become necessary to determine the origin of these structures and to interpret their behaviour. The objectives are: to study the growth form of the plant in order to analyze the ontogeny of its propagation organs, and to study its shoot and root anatomical characters that affect water conductivity. Hoffmannseggia glauca was collected in Argentina. Development of its shoot and root systems was observed. Shoots and roots were processed to obtain histological slides. Macerations were prepared to study vessel members. Primary and lateral roots originate buds that develop shoots at the end of the first year. In winter, aerial parts die and only latent buds at soil surface level and subterranean organs remain. In the following spring, they develop innovation shoots. Roots show localized swellings (tuberous roots), due to a pronounced increase of ray thickness and parenchymatous proliferation in the root center. Root vessel members are wider than those of aerial and subterranean shoots. Early development of an extensive root system, presence of root borne buds, anatomic and physiological specialization of innovation shoots, capability of parenchymatous rays to originate buds and tuberous roots, and high water transport efficiency in subterranean organs lead Hoffmannseggia glauca to display higher colonization potential than other species.

En este trabajo se analizan los sistemas de ramificacion de las siguientes Fabaceas herbaceas de la subfamilia Papilionoideas: Adesmia bicolor (Poir.) DC., A. comechingona C.A. Bianco & Weberling, A. cordobensisBurkart, A. filipes A.Gray, A. incanaVogel var. incana, A. leptobotrys Burkart, A. macrostachyaBenth., A. muricata (Jacq.) DC. var. dentata (Lag.) Benth., Clitoria cordobensisBurkart, Desmanthus virgatus (L.) Will., Galactia glaucophyllaHarms, G. latisiliquaDesv. var. latisiliqua, G. marginalisBenth., G. texana(Scheele) A. Gray var. texana, Rhynchosia diversifoliaMicheli var. diversifolia, R. diversifolia var. prostrataBurkart, R. edulisGriseb., R. sennaGillies ex Hook. var. senna, Stylosanthes hippocampoidesMohlenbr., S. montevidensisVogel var. montevidensis, Vicia pampicolaBurkart y Zornia trachycarpaVogel. El area del estudio comprende el centro de Argentina. El seguimiento de los sistemas de ramificacion fue realizado en su habitat. El primer ano de vida se interpreto en invernaculo. Las variaciones en los sistemas de ramificacion de las Fabaceas herbaceas, se deben a la combinacion de los siguientes caracteres morfologicos: Desarrollo del eje primario, presencia de ramas cotiledonares, desarrollo de ramas profilares, comportamiento de ramas accesorias, direccion de crecimiento y grado de ramificacion de los ejes, longitud y numero de los entrenudos, presencia de raices adventicias, estructura de las raices adventicias, caracteristicas de la zona de innovacion. La combinacion espacial y temporal de estos caracteres, el ciclo de vida de las especies y el habitat donde se encuentran determinan los distintos tipos de ramificacion en Fabaceas herbaceas. Estos datos basicos permiten perfilar tres usos fundamentales: 1. Fijacion de areas degradadas por la erosion eolica, 2. Utilizacion de las especies como recurso forrajero, 3. Revegetacion de sitios degradados debido al sobrepastoreo o modificados por la accion antropica. Variation and adaptive strategies of branching systems of herbaceous Fabaceae Branching systems are analyzed in the following species of herbaceous Fabaceae, subfamily Papilionoideae: Adesmia bicolor (Poir.) DC., A. comechingona C.A.Bianco & Weberling, A. cordobensis Burkart, A. filipes A.Gray, A. incanaVogel var. incana, A. leptobotrys Burkart, A. macrostachya Benth., A. muricata (Jacq.) DC. var. dentata (Lag.) Benth., Clitoria cordobensisBurkart, Desmanthus virgatus (L.) Will., Galactia glaucophyllaHarms, G. latisiliquaDesv. var. latisiliqua, G. marginalisBenth., G. texana (Scheele) A. Gray var. texana, Rhynchosia diversifoliaMicheli var. diversifolia, R. diversifolia var. prostrataBurkart, R. edulisGriseb., R. sennaGillies ex Hook. var. senna, Stylosanthes hippocampoidesMohlenbr., S. montevidensisVogel var. montevidensis, Vicia pampicolaBurkart and Zornia trachycarpaVogel. The area of study is located in the centre of Argentina. Branching systems are studied in their habitat, except for the first year of life which is interpreted in the greenhouse. Branching system variations of herbaceous Fabaceae are due to the combination of the following characters: main axis development, presence of cotyledonary branches, prophyllar branch development, accessory branch behaviour, growth direction and axis branching degree, internode length and number, presence of adventitious roots, adventitious root structure, characteristics of the innovation zone. Spatial and temporal combination of these characters, species life cycles and habitats define different branching types in herbaceous Fabaceae. This basic data outlines three important uses: 1. Fixation of degraded areas by eolic erosion. 2. Use of species as forage resource. 3. Revegetation of degraded places. Variabilitat und Anpassungsstrategien des Verzweigungssystems krautiger Fabaceae Die Verzweigungssysteme folgender krautiger Fabaceae, Unterfamilie Papilionoideae, aus Zentralargentien wurden untersucht: Adesmia bicolor (Poir.) DC., A. comechingona C.A.Bianco & Weberling, A. cordobensisBurkart, A. filipes A. Gray, A. incanaVogel var. incana, A. leptobotrysBurkart, A. macrostachyaBenth., A. muricata (Jacq.) DC. var. dentata (Lag.) Benth., Clitoria cordobensisBurkart, Desmanthus virgatus (L.) Will., Galactia glaucophyllaHarms, G. latisiliquaDesv. var. latisiliqua, G. marginalisBenth., G. texana (Scheele) A. Gray var. texana, Rhynchosia diversifoliaMicheli var. diversifolia, R. diversifolia var. prostrataBurkart, R. edulisGriseb., R. sennaGillies ex Hook. var. senna, Stylosanthes hippocampoidesMohlenbr., S. montevidensisVogel var. montevidensis, Vicia pampicolaBurkart und Zornia trachycarpaVogel. Die Verzweigungssysteme wurden an den naturlichen Standorten studiert, allein die Entwicklung im ersten Jahr wurde im Gewachshaus untersucht. Die Unterschiede im Verzweigungssystem beruhen in erster Linie auf der Abwandlung folgender Parameter: unterschiedliche Entwicklung der Hauptachse, Ausbildung von Cotyledonarsprossen, Entwicklung von Vorblatttrieben, Verhalten der akzessorischen Achselsprosse, Wuchsrichtung und Verzweigungsgrad der verschiedenen Sprossachsen, ihrer Internodienzahl und -lange, Ausbildung sprossburtiger Wurzeln und unterschiedliche Ausbildung der Innovationszone. Aus der unterschiedlichen raumlichen und zeitlichen Kombination dieser Eigenschaften und den Unterschieden im Lebenszyklus der einzelnen Arten in Anpassung an ihre Standortsbedingungen resultiert eine grose Vielfalt der Verzweigungstypen bei krautigen Fabaceae-Papilionoideae. Aus deren Kenntnis ergeben sich wichtige Daten fur die Nutzung der verschiedenen Arten.