Why are the seeds of this species difficult? This species has recalcitrant seeds, which have a high critical moisture content and will rapidly lose viability if they are dried.
Trichilia emetica (Image: Plant Germplasm Conservation Research, University of KwaZulu-Natal [Westville Campus], Durban, South Africa)
This species has Recalcitrant seeds which cannot be dried without causing a decline in viability. Do not place the seeds under sub-zero temperatures as they will suffer from freezing damage due to their high moisture content.
Fresh seeds have an initial seed moisture status above 95% equilibrium relative humidity (around 40% moisture content). Researchers have found that viability decreased to 50% following desiccation to 14.3% moisture content, and that seeds at moisture levels below this did not germinate.
Sterilise the surface of the seeds with 1% hypochlorite solution before germination. Repeat the sterilisation treatment after 10hrs if fungal proliferation continues. Germinate in trays of moistened vermiculite at 25ºC.
The seed of this species may be Physiologically Dormant (inferred from available information on germination and of characteristics of seeds in this family). If germination is low, overcome dormancy by mimicking the seasonal patterns of the species' native habitat. Use a moist pre-chill or pre-heat treatment (depending on local climatic conditions), before germinating the seeds on agar, germination paper or sand at their optimum temperature. If this does not work, you can perform delicate surgery to enable the embryo to grow. Excise the tissue near the root tip.
Trichilia emetica fruits
(Image: Plant Germplasm Conservation Research, University of KwaZulu-Natal [Westville Campus], Durban, South Africa)
The fruit is a spherical capsule containing 6-8 seeds. The seeds are black and the testa are almost completely surrounded by a bright scarlet-orange aril.
See more images of this species at Flora of Zimbabwe.
Accepted name: Trichilia emetica Vahl.
Synonyms: Trichilia roka (Forsk.) Chiov
References and Links
- Baskin, C.C. and Baskin J.M. (1998). Seeds: ecology, biogeography, and evolution of dormancy and germination. Academic Press, USA.
- Baxter, D., Erdey, D. and Berjak, P. (2004). Sensitivity of Trichilia emetica Vahl. seeds to desiccation. In M. Sacandé, D. Joker, M. Dulloo and K. Thompsen (eds) Comparative Storage Biology of Tropical Tree Seeds. IPGRI, Rome, Italy.
- AFPD (African Flowering Plants Database) - Conservatoire et Jardin Botaniques de la Ville de Genève, Switzerland, and South African National Biodiversity Institute, Pretoria, RSA: Trichilia emetica.
- Forest & Landscape Denmark - University of Copenhagen, Denmark: seed leaflet on Trichilia emetica.
- PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Trichilia emetica.
- SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Trichilia emetica.
- Tropicos - Missouri Botanical Garden, USA: Trichilia emetica.