Issued by Argentina in 1961 for the TEMEX-61 Philatelic Exhibition, this elegant semi-postal set highlights native Argentine flora in a refined monochrome design style by Héctor Viola. Each stamp features a “+” surcharge, indicating additional funds raised beyond postal value. The series includes Mburuçuya (Passiflora caerulea), Samohú (Chorisia speciosa), Tarco (Jacaranda mimosifolia), and Lapacho Negro (Tabebuia species). Printed by Casa de Moneda, the set is admired for its artistic botanical detail and harmonious color palette. A desirable thematic addition for collectors of flowers, semi-postals, and South American philately.