Reproductive Biology and Herkogamy of <i>Psychotria elata</i> (Rubiaceae), a Distylous Species of the Tropical Rain Forests of Costa Rica

Abstract

The floral morphology, breeding system and pollinators of four natural populations of Psychotria elata (Rubiaceae), found in tropical rainforests of Costa Rica, were examined. Anisoplethy and distylous morphology were observed in all studied populations. The number of flowers per inflorescence was significantly higher in the most abundant morph (p < 0.005) and the number of open flowers/inflorescence/day was similar between the morphs (p > 0.05). Reciprocal herkogamy was detected in only one of the morphs in one population. Breakdown of the heteromorphic incompatibility system was observed in the populations Tirimbina and Rara Avis. Pollen production was significantly lower in thrum morphs of Tirimbina. Seedless fruits were formed in two of the four populations. One-seeded fruits were formed in all populations and were predominant in thrum morphs of Tirimbina (9.15%) and Zurqui (75%). According to our visitation records, hummingbirds, butterflies and moths are the main pollinators of P. elata flowers.

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

“…The >80 % viability of pollen grains, a common characteristic of heterostylic species, has also been recorded in P. poeppigiana (Coelho & Barbosa 2004), P. barbiflora (Teixeira & Machado 2004), P. carthagenensis (Koch et al 2010), P. conjugens, P. sessilis, P. hastisepala (Silva & Vieira 2013), and P. elata (Silva & Segura 2015). This may assist in the reproductive success of the species (Valois-Cuesta et al 2012).…”

“…Isoplethy in P. ipecacuanha has been recorded (Rossi et al 2005), in natural populations of the Atlantic Forest in Minas Gerais and Rio de Janeiro and is consistent with the results of the present study. For the genus Psychotria, isoplethy was also recorded in other distylous species such as P. tenuinervis (Virillo et al 2007), P. brachypoda (Fonseca et al 2008), P. carthagenensis (Koch et al 2010;Faria et al 2012); P. hastisepala (Silva & Vieira 2015), P. elata (Silva & Segura 2015), P. cephalophora (Watanabe et al 2015), and P. deflexa (Matias et al 2016).…”

“…Habitat loss was one of the reasons for the low genetic diversity observed in natural populations of Psychotria hastisepala in the state of Minas Gerais (Silva & Vieira 2013). In addition, habitat loss diminishes the areas of clusters, and can cause an imbalance in the ratio between morphs (anisoplethy), as well as reducing the number of physiologically mature plants for reproduction (Silva & Segura 2015).…”

“…Pollen production per floral morph of five flowers per morph per population was calculated. One ground anther per flower was mounted on a slide in a drop of acetic carmine and the number of pollen grains was multiplied by the number of anthers per flower (Silva & Segura 2015).…”