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The breeding systems of seven understorey species in a Chaco woodland in NE Argentina were studied by means of hand pollinations and fluorescence microscopy observations of post-pollination events. Six species showed self-incompatibility (SI), with heteromorphic SI in Erythroxylum microphyllum, and probable homomorphic gametophytic SI (stylar inhibition of selfpollen tubes) in Aechmea distichantha,...
During the last decades, it has been shown that arctic plants show larger variation in reproductive strategies than traditionally assumed. Obligate outcrossing based on a self-incompatibility system is, however, very rare in the typically harsh, insect-poor arctic environment. Here we present the second, to our knowledge, documented example of a fully self-incompatible arctic species, Draba palanderiana...
Plants that live in fragmented landscapes, where populations are isolated from each other and in which long-distance dispersal is essential for colonization of empty sites, reproduction should be favoured by self-compatibility (Baker's law). Nevertheless, outcrossing mechanisms, such as self-incompatibility and dichogamy, are common in many species and are often maintained by inbreeding depression...
The main goals of the present paper were to investigate the floral biology and the breeding system of Melochia tomentosa in a semi-arid region in Brazil, comparing the role of Apis mellifera with other native pollinators, and to discuss the importance of this plant species as a floral resource for the local fauna in maintaining different guilds of specialized pollinators in the Caatinga. M. tomentosa...
The Bignoniaceae possess sensitive bilobate stigmas that close after stimulation. We determined factors involved in stigma closure and reopening in four species of Bignoniaceae from the National Parks of Catimbau, Northeastern Brazil (Anemopaegma laeve, Arrabidaea limae, Jacaranda rugosa and Tabebuia impetiginosa). The study showed that any mechanical touch promoted the stigmatic closure. Only the...
It has profound implications for species invasions and fitness, how weeds achieve reproductive success. We present the first study on the reproductive biology of Stellera chamaejasme, a toxic perennial weed which is abundant in the alpine meadows on the eastern Tibetan Plateau of China since the 1960s. S. chamaejasme has synchronogamy and herkogamous flowers, which last for about 11 days. Flowers...
Many Asteraceae species inhabit open vegetation areas and, as a rule, members of this family have dry, wind-dispersed fruits. Tilesia baccata, on the other hand, occurs in forested areas and, differently from all neotropical Asteraceae, has fleshy fruits with ornithochorous characteristics. However, no studies have confirmed the dispersion by birds or any other aspect of the reproductive biology of...
Agricultural intensification has resulted in drastic regression of several arable land-dependent weeds. This decrease, along with reduced pollinator abundance, could lead to population-level extinction of self-incompatible species. Alternatively, it could drive adaptation to self-compatibility through selection on standing genetic variation. We investigated whether pseudo-self-compatible (PSC) or...
The South-African Oxalis pes-caprae with trimorphic flowers is naturalised in many Mediterranean countries. In Italy only short-styled (S) populations are known for certain and the plant is believed to reproduce only asexually, due to self- and intramorph-incompatibility. This study aims to clarify anatomical, biochemical and ultrastructural features of the stigma and style of an Italian S population,...
Ziziphus comprises important fruit trees that inhabit arid environments of tropical and subtropical regions of the world and are able to adapt to drought and salt stress. Species of this genus are characterized by synchronous protandrous dichogamy and self-incompatibility; however, reduced seed set after hand self-pollination indicates that self-fertilization is possible and that it causes a strong...
The evolutionary trajectory of isolated or small populations of self-incompatible species depends on genetic variation in the capacity to transition to self-compatibility and the impact of inbreeding on plant fitness. Centaurea cyanus is an example of a self-incompatible, arable field-dependent weed species that is in regression in western Europe due to agricultural intensification. However, some...
We studied the reproductive biology of Cipocereus minensis, an endemic columnar cactus of the Espinhaço Mountain Range, Southeastern Brazil, focusing on floral biology, breeding system, and pollination. We described floral morphology and evaluated the role of nocturnal and diurnal pollinators on the reproductive success in two populations. C. minensis has large, horizontal, cream-colored, chiropterophilous...
Restrepia is a small Pleurothallid genus, comprising 57 species, 44 of which were discovered since 1970. These species are indigenous to Central and South America, where their montane forest habitats are under increasing pressure from changes in land use. With resulting increasingly fragmented habitats and dwindling numbers, the pollination systems of obligate out-breeding genera, such as Restrepia,...
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