Synonymy
Cereus inermis Otto in Pfeiffer (1837) Enum. Diagn. Cact. 116
Cereus kartenii (Otto) Salm-Dyck
Selenicereus inermis (Otto) Britton & Rose
Epiphyllum steyermarkii L. Croizat (1974) Photologia 28:17-20

Ethymology
This plant has no spines on its stems, hence the epithet inermis (Lat.) = unarmed..

History
This was one of the first species brought to Europe, but still very rare and I have found no certain records that it ever flowered in cultivation - probably due to wrong cultivation methods. I have never seen a photograph of this plant, just drawings.

Description
Stems scandent or pendent, clambering or sprawling, branching, producing few areal roots, slender, 2-3 m long or longer, 1-3 cm thick, 1,5-3 cm wide when flat, ca 1cm thick when angled; ribs 2-4(-5), crenate, acute, 6-7,5 mm high; areolens elliptic, 1-1,5 mm in diameter, with few bristles, internodes 2-6 cm; epidermis pale green.
Flowers 12-17,5(-20) cm long, ca 14 cm in diameter, nocturnal, scentless, tepals rotate, exceeding the stamens; pericarpel with ovate to lanceolate bracteoles and few brownish spines; peceptacle subcylindric, 6,5-8 long, 1,5-2cm in diameter with pale brown spines. outer tepals ca 13, oblanceolate to linear, acute, 6,5-7 cm long, 8-10 mm wide, reddish yellow, greenish at base; inner tepals ca 16, ligulate to linear-lanceolate, acute or acuminate, 6-7,5 cm long, 8-10 mm wide, white, sometimes base reddish to rosecoloured; stamens white, 6-8 cm long, anthers plae yellow; style 12 cm long, very thick, lobes thick 2 cm long, pale greenish or reddish.
Fruit ovod, spiny and yellow.

Origin and habitat
N South America (Colombia and Venezuela). Tropical and gallery forests. 1.000-1.300 m alt.

Systematics
Very variable. Most closely related with S. wercklei, S. rubineus and S. tricae. All of these might be best merged under the name S. inermis.

Cultivation
No records.