Miltonia (abbreviated Milt. in the horticultural trade) is a genus of twelve epiphytic orchid species and eight natural hybrids in the family Orchidaceae, subtribe Oncidiinae. The genus is almost exclusively Brazilian, with one species — Miltonia flavescens — extending into northeast Argentina and eastern Paraguay. It was established by John Lindley in 1837, when he described the type species Miltonia spectabilis.
Plants are comparatively medium-large, reaching about fifty centimetres in height, with a subcaespitous growth habit: the pseudobulbs are spaced slightly apart along a rhizome rather than tightly clustered. Each pseudobulb typically bears two narrow, flexible apical leaves up to forty centimetres long. Inflorescences arise from the base of the pseudobulb and are erect, unbranched, and may carry one to twelve flowers that open simultaneously or in succession. The flowers are waxy and nonspurred, ranging from four to fifteen centimetres across, in colours spanning white, pink, pale yellow, lilac, and dark purple — often with contrasting, patterned lips. The large, flat lip lacks a basal callus, and the short footless column bears two hard yellow pollinia. Many species have a delicate, exotic scent, sometimes compared to roses.
Miltonia is closely related to the genera Aspasia, Brassia, and Ada, all of which fall within the large subtribe Oncidiinae of the tribe Cymbidieae. The genus has a complex taxonomic history: most species were originally placed in Cyrtochilum, Oncidium, Odontoglossum, or Brassia, and the trade still sometimes conflates Miltonia with the related genus Miltoniopsis (the true "pansy orchids" of Andean cool forests). The two genera form a hybrid genus, ×Milmiltonia J.M.H.Shaw.
All species except M. kayasimae were described before 1850. M. kayasimae, discovered near Salesópolis in São Paulo State in 1976, remains the rarest member of the genus, known from only a very restricted area on Serra do Mar. The mountains between São Paulo and Rio de Janeiro are considered the distribution centre of the genus. Because of their large, long-lasting flowers, ease of cultivation, and value in hybridisation, Miltonia orchids have been popular with collectors worldwide for nearly two centuries.
Etymology
The genus name Miltonia was given by John Lindley in 1837 in honour of Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam, who held the courtesy title Viscount Milton before inheriting the earldom. Fitzwilliam was an English aristocrat, politician, patron of science and horticulture, and an orchid enthusiast.
Distribution
Miltonia species range from the province of Misiones in northeast Argentina and eastern Paraguay northward along the Brazilian Serra do Mar mountain chain and its branches to the state of Pernambuco in northeastern Brazil. The genus is predominantly found at elevations between 200 and 1,500 metres, with most species concentrated around 600–900 metres. All species are strictly epiphytic, inhabiting ventilated sites that receive ample humidity at night and early morning but are never exposed to full sunlight.
Cultivation
Miltonia orchids are considered relatively easy to grow, though their thin leaves are prone to fungal spotting when conditions are not well balanced. They require filtered, bright light — enough to stimulate flowering but not so intense as to yellow the foliage. Intermediate temperatures suit most species, though M. cuneata prefers cooler conditions and M. moreliana warmer ones; a day-to-night temperature variation of at least 10 °C is beneficial. Plants should never be allowed to dry out completely, even during the post-bloom rest period, with more frequent watering during active growth. Relative humidity of at least 65% and good air circulation are important. Balanced, moderate weekly fertiliser applications support growth. A potting mix of half-chopped sphagnum, peat, and medium lumps of charcoal is suitable; alternatively, plants can be mounted on vegetable-fibre plaques, which requires more frequent watering.
Taxonomy Notes
Miltonia was established by Lindley in 1837 with M. spectabilis as the type species. The genus has repeatedly absorbed and shed species as taxonomic understanding improved: four species of the closely related genus Miltoniopsis were held in Miltonia until 1976, and five of the six Miltonioides species until 1983. In 2001, molecular analysis by Norris Williams and Mark Chase transferred Oncidium phymatochilum to Miltonia (now accepted as Miltonia phymatochila). The genus Anneliesia, proposed in 1983 for four species with a distinctive labellum–column junction angle, has not been accepted by the scientific community. Taxonomists continue to debate whether Miltonia should be merged with Oncidium given the many connections between the two groups.
