In the plain of Retama, the basaltic lavas disappear under heaps of ashes, and pumice-stone reduced to powder.

We spent two hours and a half in crossing the Llano del Retama, which appears like an immense sea of sand.

Still the disclosure cast a spotlight on Johnson, who had served as Penson director and CEO of Call Now, Retama's parent company.

We have characterized genetic, phenotypic and symbiotic properties of bacterial strains previously isolated from nitrogen-fixing nodules of Retama sphaerocarpa from Northern Algeria.

Penson on Thursday said Johnson agreed to resign from the board, citing his position at Call Now, which holds some of Retama-related collateral.