ABSTRACT Animal-pollinated flowers may orient resources for competing activities, such as nectar production for attracting flower visitors but then saving nectar (through inhibiting nectar production or by final resorption) for the subsequent maturation of fruits and seeds. Nectar production is continuous in Nicotiana longiflora and N. alata after flower opening, but early nectar removal reduces total secreted nectar. Resource trade-off between nectar investment and seed production were experimentally assessed in manually pollinated flowers experiencing different numbers of repeated nectar removals, while controlling for maternal effects. We expected that flowers with less nectar secretion produce larger seed sets. The results showed that for both species the earlier the nectar removal during flower anthesis, the lower the total nectar secreted and the higher the mass of seeds produced. This general pattern was clearer for N. longiflora. The link between decreased nectar production and the subsequent increase in the seed set implies that resources are limited. Consequently, nectar savings during the pollination process through early nectar removal by pollinators can be interpreted as a trade-off between resources secreted by flowers for pollinator attraction and those utilized during fruit and seed maturation.

Munroa is a morphologically heterogeneous American genus of grasses, including five species with disjunct distribution in North and South America. Dasyochloa is a monotypic grass genus, common in western North America, with a controversial taxonomic position, because it has been alternatively included in Erioneuron, Koeleria, Triodia, and Uralepis. We evaluated the relationship of Dasyochloa with Munroa using a phylogenetic analysis of qualitative and quantitative morphological data. Dasyochloa was not supported as an independent genus from Munroa, as Dasyochloa and Munroa species formed a monophyletic group defined by seven synapomorphies. On this basis, we transfer Dasyochloa to Munroa, and propose the new combination M. pulchella together with the emended diagnosis of Munroa.

Munroa es un género Americano morfológicamente heterogéneo, con cinco especies y distribución disyunta en América del Norte y del Sur. Dasyochloa es un género monotípico, común en el oeste de Norteamérica, con una historia taxonómica compleja porque ha sido incluido alternativamente en Erioneuron, Koeleria, Triodia y Uralepis. En este trabajo evaluamos las relaciones de Dasyochloa y Munroa con base en un análisis filogenético con caracteres morfológicos cualitativos y cuantitativos. Dasyochloa no resultó independiente de Munroa, ya que ambos géneros formaron un grupo monofilético definido por siete sinapomorfías. Sobre esta base, transferimos Dasyochloa a Munroa y proponemos la nueva combinación M. pulchella, junto con una enmienda en la diagnosis de Munroa.