Autor: Backeberg emend. J. Lode
• ETYMOLOGY
Genus honouring the North American botanist William Taylor Marshall (1886-1957), co-founder of the association “Cactus and Succulent Society of America” in 1929, and director of the Phoenix Desert Botanical Garden in Arizona, USA, since 1946 until his death.
• DESCRIPTION
A genus of vigorous treelike plants, erect columnar, branching from the base, typically without a defined trunk, stems dark green, shiny, more or less covered with wax forming a V shape with every new growth. 6-10 thick ribs, rounded, areoles rather small, felted with brown or grey wool. Radial spines short and aciculate (4-6 of 1 cm max.); 1-3 central spines a little longer.
Flowers nocturnal, self-sterile, funnel-shaped, tuberculate and scaly, appearing towards the upper part of stems, with greenish to purple outer tepals, inner tepals pinkish white to intense pink, generating huge quantities of nectar, pollinated by bats (Glossophaga leptocyneris). Large fruits like an egg when ripe, dry, with persistent spines, dehiscing like a five petalled flower, with white or red pulp, dispersal ornithophilous (Aimophila ruficauda, Amazilia rutila, Amazona albifrons, Arati riga canicularis, Calocitta formosa, Campylorhynchus rufinucha, Crotophaga sulci rostris, Dives dives, Heliomaster constantii, Icterus gularis, I. pustulatus, Melanerpes aurifrons, Mimus gilvus, Passerina versicolor, Quiscalus mexicanus, Zenaida asiatica). Seeds large, black, smooth and shiny.
• HABITAT
The genus Marshallocereus grows in Central America, in semi arid areas, in the shade, in volcanic mountains covered with more or less dry deciduous tropical forests, sometimes at the edge of rivers, or not far from the Pacific Ocean, on rocks, together with other cacti, especially epiphytic, as well as bromeliads and orchids, from sea level up to 50 m in altitude, possibly more, but without more precise data. The average annual rainfall is about 680 mm. Both taxa are used by the local populations to make quickset hedges.
• DISTRIBUTION
Costa Rica (Guanacaste, Puntarenas), El Salvador (Cuscatlan, Sonsonate, San Miguel, La Union), Guatemala (Baja Verapaz, Chuiquimula, El Progreso, Huehuetenango, Jutiapa, Quiche, Zacapa), Honduras (Yoro), Mexico (Chiapas), Nicaragua (Leon, Madriz), Panama.
Currently 1 recognised species + a doubtful subspecies:
– Marshallocereus aragonii* (F.A.C.Weber) Backeberg 1951
– Marshallocereus aragonii subsp. eichlamii* (Britton & Rose) Guiggi 2012
References: "TAXONOMY of the CACTACEAE" - ISBN 978-84-617-3692-8 (Vol. 2)