The pollen of Phaseolus species is sensitive to temperatures exceeding 25°C, which has the effect of completely abolishing fertilization for part of the summer in areas with a hot climate.

Phaseolus acutifolius is an annual species cultivated in dry and desert areas, managing to fruit up to 35°C. They are unusually heat and drought tolerant, and are resistant or tolerant of diseases to which common beans succumb. But have a short lifespan of around 2 months and produce small grains and low yields.

A single hybrid line between these two species, it is 'Beefy Resilient Grex'.

It was developed by Carol Deep, founder and owner of Fertile Valley Seeds. And was first released as a segregating F4 population around 2012.

Date of OSSI engagement: January 2015. 

The OSSI Pledge guarantees the freedom to use these OSSI-Pledged seeds as you wish. In exchange, you agree not to restrict the use of these seeds or their derivatives by third parties by patents or other means, and to include this commitment in any transfer of these seeds or their derivatives.

This line comes from the crossing of a common bean (Phaseolus vulgaris) cv. ‘Gaucho’ X Tepary bean ( P. acutifolius) cv. ‘Black Mitla’.

Both are small beans, round in cross section and about twice as long as they are wide and are easy to beat. 

Joran's Seeds and Research has acquired seed stock in 2021 from Czech seed grower and breeder Permaseminka.

After a year of multiplication, among the seeds collected, three phenotypes were identified: a black one, representing approximately 75% of the plants; a brown, about 20% of the plants, and finally, a red, about 5% of the plants.

These three phenotypes have been isolated and cultivated separately since 2023.