Risk of genetic vulnerability and aspects of the reproductive biology of Psychotria ipecacuanha (Rubiaceae), a threatened medicinal plant species of Brazilian forests

ABSTRACT Psychotria ipecacuanha, commonly known as Ipeca, is a medicinal plant of pharmacological and economic value. The species is distylous; it has populations with two floral morphs, one with long and one with short styles. Apart from the presence of two floral morphs in a balanced ratio (1:1), reciprocal herkogamy of the reproductive organs between alternative morphs is desirable to maintain cross-pollination. The risk factors for genetic erosion and conditions for sexual reproduction in natural populations of P. ipecacuanha were investigated. The main risks for genetic erosion in four populations studied were: habitat change in the forest fragment where they occurred and in the surrounding area over the last 20 years; proximity to agricultural areas; frequency of drought affecting the forest fragment; and the area occupied by the species within the forest fragment. All evaluated populations were isoplethic with the reciprocity of reproductive organs varying across populations. Anthropogenic factors, associated with morphological and reproductive characteristics (e.g., low reciprocity between anther and stigma and low pollen production), indicate risks for the maintenance and reproduction of Ipeca in the population of the municipality of Denise. Habitat loss, small clusters, and the low number of reproductive plants jeopardize the survival of the studied populations.