Anatomy and fruit development in &lt;i&gt;Schinopsis balansae&lt;/i&gt; (Anacardiaceae)

Ana María González,José Luis Vesprini

doi:10.3989/ajbm.2254

Abstract

Gonzalez, A.M. & Vesprini, J.L. 2010. Anatomy and fruit development in Schinopsis balansae (Anacardiaceae). Anales Jard. Bot. Madrid 67(2): 103-112. Schinopsis balansae Engl. is a dioecious tree; reproduction is by woody samaras containing a single seed. Fruit set is high, even in isolated trees, empty fruits are frequent and account for a high proportion of the total fruit production. To describe the anatomy and the ontogeny of seeded and seedless fruits, flowers and fruits at different development stages from bagged and pollen exposed flowers were studied. The development and the anatomy of the pericarp in seeded and parthenocarpic fruits did not differ. It consisted in an exocarp formed sensu lato from the external epidermis of the ovary and some layers of the underlying parenchyma. The mature mesocarp was constituted by a sclerified tissue and lysigenous channels. The fruit is of Anacardium type: the endocarp presented three sclerenchymatic and a crystalliferous layer. The endocarp development was also sensu lato because it was formed from the epidermis and the hypodermis of the carpel. This organization agrees with the only species described in the genus: S. haenkeana Engl. Schinopsis balansae is able to produce parthenocarpic fruits in the absence of pollination. Empty fruits from free exposed flowers presented embryos arrested at different stages, although total absence of an embryo was the most common condition. Parthenocarpy seems to be a plesiomorphic trait within the Anacardiaceae, but regardless of its origin, the maintenance of empty fruit production in a wind-dispersed samara is difficult to explain. Whether parthenocarpy has an adaptive value, or is an evolutionary constraint remains unclear in Schinopsis.

Highlights

Schinopsis balansae Engl. is a dioecious tree that grows in Argentina, Bolivia, Paraguay and Brazil, and is the dominant species of Argentine forests called “quebrachales”
Most species of the Anacardiaceae family has drupaceous fruits, many of them adapted to different dispersers, S. balansae fruits are woody samaras with a single oblong wing
The genus Schinopsis was classified as Anacardiumtype, based only in a brief description of S. haenkeana, the endocarp was regularly guided and consists of four layers of cells: an internal crystalliferous layer and three external layers formed by sclereids in palisade

Summary

Introduction

Schinopsis balansae Engl. is a dioecious tree that grows in Argentina, Bolivia, Paraguay and Brazil, and is the dominant species of Argentine forests called “quebrachales”. Most species of the Anacardiaceae family has drupaceous fruits, many of them adapted to different dispersers, S. balansae fruits are woody samaras with a single oblong wing. A.M. González & J.L. Vesprini and an ovoid seminiferous portion containing a single seed. Due to timber logging its populations have suffered a marked reduction, and part of the area formerly covered by the species has been devoted to farming. Ecological and social importance of the species, a basic knowledge on its biology is still lacking. Schinopsis reproduces only by means of seeds and so, to determine the factors constraining fertile fruit production, how the samara develops, and whether or not pollination is necessary, is of fundamental importance for developing strategies for the conservation of this species

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