Development and morphology of the fruit and seed of the hemiparasite genus Jodina (Cervantesiaceae)

Abstract

El género monotípico Jodina es endémico del centro y sureste de América central, común en bosques y ambientes de matorral. El tipo de fruto en Jodina es controvertido, ya que se lo ha descrito en diferentes etapas de su desarrollo. El principal objetivo de este trabajo fue analizar la morfología del fruto de J. rhombifolia durante su maduración para alcanzar un consenso sobre su tipo. Asimismo, se analizaron en detalle diferentes características del desarrollo y anatomía de la semilla. El material se estudió de acuerdo con las técnicas convencionales utilizadas en estudios con MO y MEB. El fruto de J. rhombifolia es una pseudodrupa, dado que el ovario es semiínfero; la capa carnosa del pericarpio está constituida por un engrosamiento del disco y la capa dura está representada por el mesocarpio. La participación del disco como parte de la pared del fruto no se ha mencionado anteriormente. La semilla es “desnuda” —el tegumento se desintegra durante el desarrollo— y la estructura resultante es un pireno. Se discuten asimismo las interpretaciones realizadas por otros autores acerca del fruto de Jodina.

The monotypic genus Jodina is endemic of central and southeastern South America,common in forests and scrubland environments. It belongs to the Cervantesiaceaefamily which includes eight genera that formerly belonged to Santalaceae s.l. Jodina rhombifolia is a hemiparasitic tree characterized by its rhombic and coriaceous leaf blades, glabrous surfaces, with a prominent spine at each vertex, and bisexual flowers with a nectary disk, a fleshy fruit and only one seed. The fruit type in Jodina is controversial since it has been described at different stages of development. The main objective of this work was to analyze the morphology of the fruit of J. rhombifolia during its maturation to attain a consensus about the fruit type. Also characteristics of seed development and anatomy which remained incomplete were analyzed in detail. Material was processed according to conventional techniques for LM and SEM studies. The fruit of J. rhombifolia is a pseudodrupe since the ovary is half-inferior; the fleshy layer of the pericarp is constituted by an increase of the nectary disk whereas the stony layer is represented by the mesocarp. Participation of the nectary disk as part of the fruit wall has not been mentioned previously. The seedis "naked" (the integument disintegrates during development) and the resultingstructure is a pyrene, sometimes mistaken in Santalaceae s.l. with the type of fruit nut. The interpretations made by other authors on the fruit type of Jodina are discussed.