Miltonia

Miltonia, abbreviated Milt. in the horticultural trade, is an orchid genus comprising twelve epiphyte species and eight natural hybrids. The miltonias are exclusively inhabitants of Brazil, except for one species whose range extends from Brazil into the northeast of Argentina and the east of Paraguay.
The genus of "Miltonia" was established by John Lindley in 1837, when he described its type species, "Miltonia spectabilis". Formerly many more species were attributed to "Miltonia", however, beginning in 1978, the miltonias from Central America and from cooler areas of northwest South America have been moved to other genera, including Miltoniopsis and Oncidium, and these changes are still in the process of being accepted by the horticultural trade.
"Miltonia" species have large and long lasting flowers, often in multifloral inflorescences. This fact, allied to being species that are easy to grow and to identify, make them a favorite of orchid collectors all over the world. Species of this genus are extensively used to produce artificial hybrids.
Despite the fact that "Miltonia" is now a well established genus, most of its species were originally classified under other genera as "Cyrtochilum", "Oncidium", "Odontoglossum", and "Brassia". All were discovered between 1834 and 1850 with the exception of "M. kayasimae", discovered only in 1976.
These orchids have two leaves, arising from a pseudobulb, covered with a foliaceous sheath. The inflorescence consists of waxy, nonspurred flowers. The lip is large and flat and lacks a callus at its base. They possess a footless column with two hard pollinia. The flowers have a delicate, exotic scent, some compare to that of roses.
They are named after Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam, formerly Viscount Milton, an English aristocrat, politician, patron of science and horticulture, and orchid enthusiast.
The species in this genus are sometimes referred to as the pansy orchids, but it is the "Miltoniopsis" orchids that have flowers that closely resemble the pansy. Almost everyone except for the most serious orchid hobbyists use the name pansy orchids interchangeably, which may cause confusion.
"Miltonia" looks more like "Oncidiums" than the other pansy orchids. The most "pansy-like" a "Miltonia" can get is the species "Miltonia spectabilis". Taxonomists are debating whether to combine "Miltonia" with the genus "Oncidium" because of the many connections between the two.
"Miltoniopsis" is the pansy orchid with huge showy flowers. They grow in cooler climates and are more challenging to grow than "Miltonia".
This genus forms with "Miltoniopsis" a hybrid genus ×"Milmiltonia" J.M.H.Shaw.
Distribution.
"Miltonia" species range starts on the area of Missiones in the northeast of Argentina and east of Paraguay and spreads north along the Brazilian mountains of Serra do Mar and its branches up to the State of Pernambuco on Brazilian northeast. They occupy mostly areas between 200 and 1,500 meters of altitude meters, however the majority of the species are more often found about 600 to 900 meters. "Miltonia" species can be found from shady areas inside the forest to areas more exposed to the sun, however never are under full sunlight; usually in ventilated places where they receive plenty humidity during the night and early morning. They are always epiphyte and, because they grow very fast, each pseudobulb originating two new growths every year, they soon form large colonies.
"Miltonia russelliana" and "M. flavescens" are the ones with the widest dispersion and found at lower altitudes. "M. flavescens" is the only species that exists in countries other than Brazil and is also the one that spreads farther north. "M. russelliana" range starts on Rio Grande do Sul and ends at Bahia State. "M. regnellii" is also widespread although does not go northern than Rio de Janeiro. "M. moreliana" is a species more common at lower altitudes and warmer areas existing from Rio to Pernambuco. "Miltonia candida", "M. clowesii" and "M. spectabilis" are restricted to the four states of Region Southeast of Brazil. "Miltonia cuneata" is just from São Paulo and Rio and the one that grow at highest altitudes. "M. kayasimae" is the only species really rare; it has been found just a couple of times in a very restricted area close to Salesópolis, in São Paulo State. The mountains area between São Paulo and Rio de Janeiro, where almost all species do exist may be considered the center of distribution of "Miltonia".
Description.
"Miltonia" are comparatively medium large orchid plants reaching about fifty centimeters height. They present subcaespitous growth, that means their pseudobulbs are not tightly packed but slightly spaced by a rhizome, that is longer than on caespitous plants, with length between two and five centimeters. Their roots grow along the rhizome in high numbers. They are white, comparatively thin, usually short and hardly branched. The rhizome is covered by dried imbricating steaths which get increasingly larger at the base of pseudobulb becoming articulated foliar steaths that partially cover them. The pseudobulbs and leaves vary in color from yellowish bright light green to olive green depending on the species and to the amount of sunlight they are exposed to. They may be more oval and laterally highly flattened to slightly tetragonal and elongated and almost always bear two apical leaves. The leaves are narrow, flexible and hardly larger than three centimeters wide and forty long with the apexes rounded sometimes slightly pointed. Some species are about half of this size. The inflorescences are one or two per pseudobulb, shoot from their bases behind the protecting steaths. They are erect and never branched, often longer than the leaves, bearing from one to twelve moderately spaced flowers that open at the same time or in succession holding three or four opened all the time, when the older fades a new one opens. The older flowers of species with white lips that open in succession usually get yellower about the time the next flower opens although they still last one more week before fading. The first to bloom is "M. cuneata", during late winter, but the majority of species bloom from late spring to late summer.
The flowers of "Miltonia" vary from four to fifteen centimeters across; the larger are the ones with fewer flowers. Their colors vary from entirely white and pink to dark purple, pale yellow or lilac when plain, or they may highly spotted but then usually they are greenish or brownish with a contrasting labellum often white with purple dots, stains or veins close to the base. The petals and sepals shapes are highly variable from species to species but always somewhat similar to each other within a species. They may be erect and flat or sometimes less open. The labellum is simple or very slightly lobed, usually very wide and showy without salient calli although normally showing more or less subtle keeled thickenings close to the base, usually of different colors; it is much larger and wider than the other segments, often flat but in "M. candida" embraces the column and in all species it is slightly fused to the column at their bases. The short column does not have a foot and presents two lateral auricles sometimes merged to each other through a fringe that surrounds the superior edge of the clinandrium. The anther is apical and bears two yellow hard pollinia. They possibly are pollinated by bees.
Taxonomic notes.
The first species to be described, among the ones today classified under the genus "Miltonia", was originally published by John Lindley, in 1834, as "Cyrtochilum flavescens". In this description Lindley notices that the flowers of this species turn orange color when drying and, for some confusion regarding the origin of the species, attributes it to Mexico instead of Brazil. Two years later Lindley described another "Miltonia" species but, then, under the genus "Oncidium", as "O. russellianum" in homage to Duke of Bedford. When describing this plant, Lindley considered it as a "transition species" pointing out that it was very different from the average "Oncidium" because of its purple colors and undivided lip.
In 1837, Lindley received from Mr. Loddiges and from George Baker two other specimens of a very distinctive new species. Recognizing then this should in fact be a new genus, he proposed the name "Miltonia" to it as a homage to Charles Wentworth-Fitzwilliam, 5th Earl Fitzwilliam, formerly Viscount Milton, an English orchid enthusiast. Lindley states then that the limits between a number of Oncidiinae genera, "Cyrtochilum", "Oncidium", "Odontoglossum", "Brassia" and "Miltonia", at that time classified as Vandaea, were yet to be perfectly established; although closely related, the differences should possibly be: "Oncidium" has a column with two ears and labellum distinctively lobed; "Miltonia" has a column with two ears and an entire labellum partially united to the column base; "Odontoglossum" and "Cyrtochilum" have winged columns and entire labelli but the former has it partially united to the column; and "Brassia" does not have any appendages on the column. Although Lindley described the genus "Aspasia" (which is the most closely related to "Miltonia") in 1833, both by flower and vegetative morphologies, he did not mention it on his "Miltonia" description.
Three other Botanists were working with "Miltonia" species around the time Lindley described this genus. All recognized these plants should be classified under a new genus and, as communications were slower then, all proposed new genera: Knowles and Westcott also received also a plant of "M. spectabilis" and, just one month after Lindley, proposed for it the genus "Macrochilus", calling the species "Macrochilus fryanus"; the other one was Rafinescque who, in 1838, decided that the "Oncidium russellianum" already described by Lindley in 1836 should be under another genus and created for it the genus "Gynizodon". Both "Macrochilus" and "Gynizodon" are synonyms of "Miltonia" and no other species has ever been submitted to them.
As "Miltonia" species are common plants, comparatively large, with also large flowers of bright colors, that, moreover, are spread mostly over an area of early settlements in Brazil all species but one were already described in 1850; six of them by Lindley, "M. regnellii" by Reichenbach and "M. moreliana" by Achille Richard. Despite the early description of "M. moreliana" in 1848, and two other as "M. rosea" by Lemaire in 1867, and as "M. warneri" by George Nicholson in 1886, Arthur Henfrey reduced it to a variety of "Miltonia spectabilis" in 1851, and as such it was considered until 2002, when Cássio van den Berg reestablished it as a distinct species. The last "Miltonia" species to be discovered was "M. kayasimae", found by an orchid collector not far from the city of São Paulo, in an area around nine hundred meters of altitude nearby the top of Serra do Mar mountains. It was named after their collector by Guido Pabst in 1976. So far very few plants were found, all living at the same area.
Since the genus "Miltonia" was established, many species, now classified under a number other genera, were submitted to it. The most noticeable cases were four of the five species of "Miltoniopsis", a genus proposed in 1889 but only really accepted in 1976. Despite its somewhat similar flowers, "Miltoniopsis" are from cooler forests on the Andean slopes closely related to "Cyrtochilum" and only remotely related to "Miltonia". Also five of the six "Miltonioides" species were occasionally considered as "Miltonia" until 1983 when Brieger and Lückel proposed this genus for them. These are species of more delicate and narrower flowers, from Mexico and Central America, which some taxonomists claim might be better classified under the genus "Oncidium" to whom they are closely related. The last common species which was occasionally classified under "Miltonia" is "Chamaeleorchis warszewiczii", which is related to "Oncidium" and some taxonomists identify as "Oncidium fuscatum".
In 1983, Brieger and Lueckel, considering that four species of "Miltonia", "M. candida", "M. cuneata", "M. kayasimae" and "M. russelliana", show the junction of the labellum with the column in a different angle than the other species, proposed the genus "Anneliesia" for them. Although this four species form a small sister clade to the rest of "Miltonia" species, the difference did not seem important enough to justify the acceptance of this new genus, therefore this proposal has not been generally accepted by the scientific community.
In 2001, based on molecular analysis, Norris Williams and Mark Chase, transferred a species previously classified under the genus "Oncidium", as "O. phymatochilum", to "Miltonia". As this species shows a morphology that closer to "Oncidium" species than to "Miltonia", because of its small yellowish flowers and highly branched inflorescence, this result and following transfer was a great surprise to most taxonomists. In 2005, Eric Christenson suggested a new genus and the name "Phymatochilum brasiliense" for it. There is no consensus about the name to be generally accepted as yet.
Molecular analysis show that "Miltonia" most closely related genus is "Phymatochilum" and then "Aspasia", "Brassia" and "Ada", which are the most important genera included in this that is one of the eight clades that form the subtribus Oncidiinae of tribus Cymbidieae.
Species.
The species of "Miltonia" show many differences to each other are very easy to identify, therefore, just the most evident differences are mentioned here; more details are given on individual species articles. The species are presented here according to their morphology and this order keeps no correspondence with phylogenetic relationships.
Regarding vegetative morphology "Miltonia moreliana" and "Miltonia spectabilis" can be immediately separated from the rest because their much flatter pseudobulbs, longer rhizome and inflorescences completely covered by flattened bracts that bear only one highly flat flower. These are the species with largest flowers in the genus. They are closely related and usually are recognized because the flowers of "M. moreliana" usually have dark purple petals and sepals and the lip of a lighter bright purple while "M. spectabilis" has very light purple or white petals and sepals and a purple veined labellum, however, the real technical difference among the species is on the proportions of their segments which are much wider. Despite colors are often mentioned to identify species they are not accepted by taxonomy as enough to establish distinct species by themselves. All other "Miltonia" species have similar vegetative appearance and only can be positively identified by their flowers.
Three species are unique: "Miltonia flavescens" has the most narrow flowers, almost star shaped, with all segments of straw color with some purple bots on the base of petals and sepals which are more intense on the labellum almost forming stripes; "Miltonia candida" is the only species with a labellum that embraces the column in a way that reminds the "Cattleya" species; "Miltonia russelliana" is the less showy of "Miltonia" species because its sepals and petals do not really open, being always bent over the column, revealing only the lighter tip of its purple labellum.
"Miltonia regnellii" shows the widest flower color variation among all "Miltonia" species; they can vary from white to yellow, pink and lilac with labelli also varying from white to dark purple. The flowers open in succession and slightly resemble the ones of "M. spectabilis" although much smaller. They actually are the "Miltonia" species with the smallest flowers.
"Miltonia kayasimae" and "Miltonia cuneata" are somewhat similar and possibly are closely related, both have straw color petals and sepals almost entirely covered by large brown stains and white labelli, however, they show different proportions on the flowers segments. "M. kayasimae" has much wider petals and sepals and smaller labellum which, moreover, has a larger and more salient and complex entirely purple callus on its base which is delicate, more straight and simple, and just occasionally purple dotted on its apex on "M. cuneata".
"Miltonia clowesii" has the same color pattern of "M. russelliana" with light yellow greenish brown sepals and petals completely covered with large darker dots or stains and labellum of bright purple at the base and lighter apex, however here they are whiter. On the other hand, "M. clowesii" flowers' pointed segments are larger and wide opened making it resemble a spider.
Natural hybrids.
Considering its limited number of species, it is surprising that eight natural hybrids of "Miltonia" are currently known, a number that almost equals the number of species and also implies that the most important pollinator of the majority of the species possibly is the same. As the crossing of two species uses to produce variable plants most of these hybrids have been described more than once and some have three or four synonyms. 
"M. spectabilis" is the species which has produced the largest number of hybrids, five: "Miltonia × bluntii" when crossed with "M. clowesii", "Miltonia × cogniauxiae" with "M. regnellii", "Miltonia × flava" with "M. flavescens", "Miltonia × leucoglossa" with "M. candida" and "Miltonia × rosina" with "M. cuneata", furthermore it is possible there is also one with "M. moreliana", which has not yet been described because "M. moreliana" itself was earlier considered a variety of "M. spectabilis".
"M. candida", besides the hybrid already mentioned with "M. spectabilis", also produced two others: "Miltonia × binotii" with "M. regnellii" and "Miltonia × lamarckeana" with "M. clowesii". The remaining hybrid, "Miltonia × peetersiana" was previously considered a synonym of "M. × bluntii" but because "M. moreliana" is now a species distinct from "M. spectabilis" it is its hybrid with "M. clowesii", which has entirely purple flowers instead the one with light brown petals and sepals.
Cultivation.
Despite being easy to grow, "Miltonia" species tend to be subject to spots on their thin leaves, generally caused by fungi proliferation and normally, when exposed to the amount of light they need to a full bloom, their foliage gets a bit too yellow-colored, although they should never be exposed to full sunlight. Finding the right balance of light exposure to avoid yellow leaves but still produce nice blooming is important and with some precautions the grower will succeed. They are not terribly sensitive to temperature, but they do vary according to their species make-up and origin; "M. cuneata" being one that grows cooler and "M. moreliana" the warmer growing, but all species under intermediate temperature with at least 10 °C of variation between day and night. Despite the fact that they exhibit a rest period after blooming, "Miltonia" always need to be watered, and more abundantly during active growth and blooming. they need at least 65% relative humidity and good ventilation all the time. Moderate weekly fertilizing with a balanced formula is beneficial during active growth. They may be potted in a compost of half-chopped Sphagnum, peat, and some medium-sized lumps of charcoal, or mounted on plaques of vegetable fiber, however if mounted they will need more frequent waterings.
Intergeneric hybrids.
Hybrids between "Miltonia" and orchids from other genera are placed in the following nothogenera: