Phaseolus lunatus

Why are the seeds of this species difficult? Seeds harvested in the wild may have physical dormancy, which can be overcome by scarifying the seed coat to allow water uptake and encourage germination.

Phaseolus lunatus (Image: S. Wood, RBG Kew)

Seed Storage

This species has Orthodox seeds - dry to 15-20% eRH and store at -20ºC, or as cool as possible.

Germination Requirements

Germinate on agar germination paper or sand at 25ºC, or using an alternating temperature regime of 30/20ºC (with an 8/16hr photoperiod).

Seeds from cultivated varieties of this species do not display dormancy. However seeds harvested from plants growing in the wild may be Physically Dormant (based on other species in the same genus). It may be necessary to chip the seed coat with a scalpel before placing under germination conditions, in order to overcome dormancy.

Seed Morphology

Phaseolus lunatus
(Image: S. Wood, RBG Kew)

The seed pods (5-12 cm x 1.5-2.5 cm) are oblong and generally curved backwards, containing 2-4 seeds. The seeds (1-3 cm long) are variable in size, shape and colour, ranging from flat-seeded to rounded seeds. The hilum is white with translucent lines radiating from it to the outer edge of the seed coat.

The pods turn yellow at maturity.

See more images of this species at the Digital Atlas of Economic Plants.

Taxonomy

Family: LEGUMINOSAE-PAPILIONOIDEAE

Accepted name: Phaseolus lunatus L.

Synonyms: Phaseolus limensis Macfad.

Common name: butter bean, lima bean

References and Links

Food and Agriculture Organization of the United Nations and International Plant Genetic Resources Institute (1994). Genebank Standards. FAO/IPGRI, Rome, Italy.
International Seed Testing Association (2010). International Rules for Seed Testing: edition 2010. ISTA, Bassersdorf, Switzerland.
Purseglove, J.W. (1968). Tropical Crops: dicotyledons. Longman Group Ltd., UK.
Rao, N.K., Hanson, J., Dulloo, M.E., Ghosh, K., Nowell, D. and Larinde, M. (2006). Manual of seed handling in genebanks. Handbooks for Genebanks No. 8. Bioversity International, 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: Phaseolus lunatus.
PROTAbase (Plant Resources of Tropical Africa) - Wageningen, Netherlands: Phaseolus lunatus.
SID (Seed Information Database) - Royal Botanic Gardens, Kew, UK: Phaseolus lunatus.
Tropicos - Missouri Botanical Garden, USA: Phaseolus lunatus.