Abstract The internal structure of seeds is relevant to germination, seedling establishment, and early plant growth. The objective of this work was to evaluate whether internal seed structure can influence germination and initial growth in four native woody species of the Cerrado. The species chosen for this study were Anadenanthera falcata, Stryphnodendron adstringens, Stryphnodendron polyphyllum, and Tabebuia aurea. Seeds were dissected to evaluate: the lengths of the hypocotyl-radicular axis, the epicotyl and the embryonic axis, mass of the cotyledons and the embryonic axis, and eophyll number (preformed organs). Another group of seeds was germinated in a greenhouse for sixty days to verify the emergence of the epicotyl, eophylls, metaphylls, and to measure seedling biomass. Only A. falcata presented a plumule with differentiated eophylls. Anadenanthera falcata germinated before the other species in the greenhouse and had faster epicotyl and leaf emergence. Possibly, the presence of eophylls inside the seed enabled A. falcata seedlings to carry out photosynthesis, grow faster, and accumulate more aerial biomass than the other species soon after emergence. The presence of eophylls in a differentiated embryo (as in A. falcata) may hasten germination and favour seedling establishment.

Abstract The 2011 Puyehue-Cordón Caulle volcanic eruption left vast areas of Nothofagus pumilio forests covered by high volumes of tephra, which buried the understory. This event offered a unique opportunity to analyse the impact of recent tephra deposition and the main environmental factors affecting the growth of N. pumilio seedlings. To this end, three study sites were selected and sampled three years after the eruption, two with a thick tephra layer (50 cm) but with different tree conditions: i) most trees alive or ii) most trees dead, and a third site, iii) with minimal tephra deposition. From each site, five N. pumilio 18-month-old seedlings were collected, morphometrically measured (shoot, epicotyl and main root length; shoot, epicotyl and root collar diameter), and environmental factors were also registered (light intensity, soil pH and conductivity, available P, bulk and particle soil density, and porosity). The main results indicated that three years after eruption the site with tephra deposition and dead trees (the most near to the crater) had the biggest seedlings, the lowest pH and the highest values for available P and light intensity. This temporally unique geological event showed that the regeneration potentiality of N. pumilio is high when environmental factors allow direct incident light on a substrate with high mineral content, even when the environment has previously been subjected to a significant degree of disturbance. Given the recurrence of volcanic events in Northern Patagonia, this subject merits further long-term study.

Torres, C. D. & J. G. Puntieri. 2014. Prunella laciniata (Lamiaceae), new record for the Argentinean flora. Darwiniana, nueva serie, nueva serie 2(2): 243-247. Prunella is a genus of perennial herbs native to Eurasia and northern Africa. This genus includes eight species, among which P. vulgaris is the most widely distributed. This species grows as a weed throughout the world, including America and Argentina. Here, the presence of the less common species, P. laciniata is reported for the first time in Argentina. The described material was collected in Lanín National Park, Neuquén province. A morphological description of the collected specimens of P. laciniata is provided, highlighting the differences between this species and P. vulgaris, together with an illustration and distribution map in Argentina.

Prunella es un género de especies herbáceas perennes, originarias de Eurasia y el norte de África. Este género incluye ocho especies, entre las cuales P. vulgaris es la de más amplia distribución, ya que se presenta como maleza en casi todo el mundo, incluyendo la mayor parte de América y la Argentina. El presente trabajo informa, por primera vez, la presencia en Argentina de una especie menos común, P. laciniata. El ejemplar determinado se encontró en el Parque Nacional Lanín en la provincia de Neuquén. Se describe morfológicamente el material de P. laciniata encontrado, destacando sus diferencias con P. vulgaris, y se aporta una ilustración y el mapa de distribución en Argentina.