A field survey and two field experiments were carried out to compare the performance of rhizomes and stolons of Cynodon dactylon, in terms of their sprouting efficiency and the dynamics and growth characteristics of the established ramets. The survey examined the relationships between morphological characteristics of aboveand below-ground structures of ramets naturally established from both types of fragments in a crop field. The first experiment compared the emergence and early growth of ramets from standardized stolon and rhizome fragments, grown under uniform field conditions without competition. It also comparatively analysed the predictive value of the maximum stolon length on dry matter partitioning. The second experiment investigated fragment type · size interactions on the establishment, dry matter accumulation and partitioning in stolon-and rhizome-originated ramets. Results showed that under normal cropping conditions, more ramets can be originated from rhizome than from equivalent stolon fragments. Higher sprouting efficiency and dry matter partitioning to aerial structures, and a higher size dependence of the effective ramet recruitment were observed for stolon than for rhizome fragments. The observed differences between fragment type are dicussed in relation to their implications for predictions of weed emergence, and the efficacy of control strategies used under different cropping tillage systems.

Lotus glaber Mill. is a herbaceous legume, tolerant to flooding, that in a few decades has colonised the Flooding Pampa grasslands, an extensive wetland of 90 000 km in central-east Argentina. In this study, the growth and nodulation of flooded plants in 5 local populations were evaluated. Thirty-day-old seedlings, grown in pots, were flooded outdoors during 4 months. Stem, leaf, and root biomass, as well as the number of nodules per plant, were lower in flooded plants than in non-flooded ones. In flooded plants, the submerged portions of stems were hypertrophied and populations differed in the proportion of plants with adventitious roots. Flood tolerance was significantly related to the proportion of plants with adventitious roots in stems of each population. A positive relationship was shown between the proportion of plants with adventitious root and number of nodules per plant. The plants were also tolerant of low temperatures and ice-sheeting of water. These results underline the importance of morphological adaptations related to the maintenance of plant functionality under flooding conditions. The results provide evidence of the existence of characters related to flooding tolerance, which should be taken into account in ecological studies and agronomic selection programs

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