Mariano Lagasca y Segura was born in Encinacorba, Province of Zaragoza, in Spain on 4 October 1776 to a wealthy Catholic family.

[1] In 1800, he moved to Madrid where he met Antonio José Cavanilles, a well-known botanist and doctor and became his disciple.

[1] In 1802, he co-published with Simón de Rojas Clemente y Rubio a volume of articles regarding medicine and botany.

He spent the following eleven years in London, until his return to Spain in 1834 where he regained his position as a director of the Royal Botanical Garden of Madrid.

[3] In 1827, he edited and printed his herbarium work Hortus siccus Londinensis; or a collection of dried specimens of plants, growing wild within twenty miles round London, named on the authority of the Banksian herbarium, and other original collections which might be an exsiccata-like series with duplicate specimens.