Seed (true seed plus endocarp) dormancy in Anacardiaceae in relation to infrafamilial taxonomy and endocarp anatomy

Abstract Information in the literature and unpublished results of the authors on Dobinea were used to determine the kind [class(es)] of seed (true seed + endocarp) dormancy and of non-dormancy of genera in all five tribes of Anacardiaceae, and the results were examined in relation to the taxonomic position and endocarp anatomy within the family. Reports of both seed germination and endocarp anatomy were found for 15 genera in tribe Spondiadeae, 6 in tribe Anacardieae, 30 in tribe Rhoeae, 3 in tribe Semecarpeae and 1 in tribe Dobineeae. In Spondiadeae (Spondias-type endocarp), Anacardieae, Semecarpeae and Dobineeae (Anacardium-type endocarp), seeds are either non-dormant (ND) or have physiological dormancy (PD). In Rhoeae (Anacardium-type Rhoeae Groups A, B, C and D endocarps), on the other hand, seeds are ND or have physical dormancy (PY), PD or PY + PD. PY/PY + PD in this tribe seems to be restricted (or nearly so) to Rhus s.s. and closely related genera (e.g. Cotinus, Malosma and Toxicodendron) with an Anacardium-type Rhoeae Group A endocarp. However, seeds of other genera (e.g. Astronium and Schinus) with this type of endocarp and those with Rhoeae Group B (e.g. Pistacia), Group C (e.g. Pentaspadon) and Group D (e.g. Heeria) endocarps are either ND or have PD. The fossil fruit record strongly suggests that present-day relationships between diaspore dormancy (or non-dormancy), endocarp structure and taxonomic position within Anacardiaceae extend back to at least the Palaeogene.