Seed dispersal, directed deterrence and germination in gifboom (Hyaenanche globosa; Picrodendraceae) seeds

We investigated seed dispersal, directed deterrence and germination in the Cape narrow-endemic plant Hyaenanche globosa (gifboom). We found that gifboom seeds were predominantly removed and cached by the known scatter-hoarding specialist, small mammal, Acomys subspinosus, a first case of scatter-hoarding in the Picrodendraceae and the first case of a recalcitrant seed being scatter-hoarded in Cape fynbos. This represents an unusual exception to most hard-seeded, dormant scatter-hoarded seeds. In contrast, the ubiquitous, generalist, small mammal Micaelamys namaquensis, which is known to consume a variety of seeds, ignored gifboom seeds. The seeds, which contain the toxins, appear to have a directed deterrence effect on this common seed predator. We show that imbibed gifboom seeds produce copious mucilage, due to pectins, which aid in germination. Gifboom seeds appear to have two novel mechanisms for increasing seed to seedling survival, including toxins for seed predator deterrence and mucilage production for enhanced germination. ? 2020 SAAB. Published by Elsevier B.V. All rights reserved.

Automated summary

The study showed that gifboom seeds were predominantly removed and cached by small mammal Acomys subspinosus, while Micaelamys namaquensis ignored them. Gifboom seeds contain toxins with deterrent effects on seed predators and produce mucilage to enhance germination.