The Oncidium Section CRISPA

 

A number of species from the Crispa Section, together with their hybrids are found in many orchid collections. With spectacular flowers produced when well grown, both the species and their hybrids are increasingly popular.

Garay and Stacy2 state the distinguishing features of this Section are the plants conspicuous pseudobulbs. The petals and sepals are noticeably clawed or constricted at their bases, the lateral sepals are variously joined, as long as or shorter than the lip. The petals are large, often more conspicuous than the sepals. The disc of the lip carries an uneven number of tubercules (projections), and the rostllum is short.

The first species discovered, and after which the Section is named, was crispum first described by Loddiges in his Botanical Cabinet of 1832. Subsequently a considerable number of somewhat similar plants have been discovered and introduced into cultivation. It was widely thought that there were in fact only very few valid species, and that the varieties and colour forms represented an inter-hybridised complex of these. Some of the plants listed in The Dictionary of Cardening6 indicate this view. Fowlie,34 who had undertaken a critical review of plants in this Section, believes that many separate species are involved. The characteristics of the individual species, he contends, are separately maintained by the fact that they grow over a distinct geographical range, have different altitudinal limits, flower at different times of the year, and probably require different insect pollinators as the flowers differ somewhat structurally, and the scents Oncidium crispum also show variations. He reports34 from a study of a considerable number of jungle collected plants, that natural hybrids in fact were found to constitute less than 0.1 of 1% of the specimens.

The plants generally produce quite large and spectacular flowers which last well. A collection of a number of different species can provide plants in flower virtually all year, with perhaps the exception of late winter. In these days of high energy costs, they have the advantage of being cool growing, at least during the winter months.

The plants are endemic to Brazil, mostly being found in the Organ Mountains region close to Rio de Janeiro. They are all found at moderate altitudes. Sometimes known to be somewhat intransigent under cultivation, if their particular cultural requirements are applied, they should be maintained and brought into flower successfully.


THE SPECIES

It is appropriate to consider briefly the characteristics of the species, as this may help in the understanding of these plants, and perhaps to clarify somewhat details of their culture. Fowlie3 has shown the plants in the order of their seasonal flowering sequence, and as this appears logical, will be repeated here. As the species can be (and often are) confused, each will be described, although Fowlie's work34 should be referred to for excellent colour photographs if specific specimen identification is being attempted.


Onc. marshallianum was first described in the Gardener's Chronicle in 1866, from plants imported into the United Kingdom by Messrs Low and Co., and flowered in the collection of a Mr W. Marshall of Enfield, after whom it was named.34

Fowlie states34 that this is the first of the Section to flower in the early spring in its native Brazil, normally revealing its splendour from September to early November. Hawkes1 describes the plant as having clustered pseudobulbs, compressed, with a long oval shape, standing 100 to 150 mm high, and topped by usually two rather leathery leaves, which are some 300 mm long. Fowlie34 states this species is uncharacteristic of plants in this Section as the pseudobulbs lack anthocyanin (red) pigmentation, remaining a deep green colour, even when exposed to strong sunlight. The inflorescence comprises a many branched panicle, which for some I.5 metres, or more. The flowers can vary, but in the best forms are some 75 mm in length.34 The dorsal sepal is dull yellow, barred with pale red-brown, somewhat egg shaped and concave. The two lateral sepals are joined for about one third of their length, and are almost concealed by the lip. Petals are a vivid canary yellow, irregularly spotted red-brown in the centre. The lip's two lateral lobes are reduced to small ears, the mid lobe large, spreading, two lobed, bright yellow, broadly oblong, and rather wavy margined.6 Fowlie3 mentions it is faintly scented.

It is reported34 to grow on the very cool seaward facing slopes of the Organ Mountains in Brazil, approximately 1,000 to 1,250 metres above sea level.

Onc. crispum, perhaps the most widely known of the species in this Section, is the second species to flower in the Brazilian springtime, from October to December. Found at an altitude of 750 to 1,150 metres above sea level. It is reported to occur on both the windward and leeward slopes of the Organ Mountains, although it is also reported from other localities.34 The flowers are the largest of this Section sometimes over 75 mm in diameter.34 The flowers last in good condition for some three to four weeks.7 The pseudobulbs are clustered, oblong, compressed, ribbed and furrowed, being some 75 to 100 mm long. Two to three thick leaves are present, 150 to 200 mm long, 25 to 60 mm wide. The inflorescence is erect, or arching under the weight of 40 to 80 flowers, extending for up to 750 mm. The individual flowers can be quite variable. In the usual forms they are some 50 to 75 mm in diameter, all segments greatly crisped and undulate, bright chestnut-brown in colour, sometimes more or less spotted and margined with vivid yellow.1 One variety, ochraceum, has the red anthocyanin pigments supressed, producing ochre coloured flowers.34 This species is sometimes known as grandiflorum, with a supposedly larger flower form also given this varietal designation, although Fowlie states both these names are invalid. The flowers are described as having a faint musty odour:34

Onc. praetextum is a plant flowering mid spring, usually from October to December, and again is native of the Organ Mountains, although is found elsewhere. Occurring at an altitude of between 1,375 to 1,600 metres above sea level, it enjoys living on trees which perch out over the abyss with outstretched semi-horizontal limbs, especially on the windward or moist side of the ridge. The plants clamber around the tree limbs, and are bathed in the upsweeping moisture laden air currents. They prefer moss shrouded perches on the larger trees, in sites where they receive bright light.35

The pseudobulbs are coloured dark green but show a 'frosted' appearance from a white powdery substance which persists on the new growth, but which is also found to some extent on the older pseudobulbs.34 The pseudobulbs are ovoid, 35 to 50 mm long. The leaves are paired, to 200 mm long. The inflorescence is up to 1.2 metres long, an arching panicle, many flowered. The flowers are fragrant, about 35 mm in diameter, the sepals pale chestnut-brown, barred yellow. It has a broad lip, the mid lobe fan shaped, yellow with a broad brown margin.1

Onc. pectorale, an often confused and 'lost' species until it was recently rediscovered, comes from the Serra do Mar, to Sao Paulo.34

Described initially in 1840, the original type illustration created considerable subsequent confusion concerning its true identification. It was named in deference to the ornately ornamented callus, which reminded the original describer of the breastplates of the soldiers of the day. Pseudobulbs are small, 40 to 50 mm high, 25 mm wide. Light green in colour, they are also covered by an obscure powdery material. Two apical leaves are 150 to 200 mm long, 20 to 25 mm wide. This species is often found in the more southern regions of Brazil, and therefore desires slightly cooler conditions, and should be only sparsely watered, especially during winter. The flowers show a clear yellow labellum, with a bright red-crimson callus. 4

This species was once thought to be a natural hybrid between forbesii and marshallianum. 6

The flowers which appear in the late spring, November,36 are bright yellow, thickly spotted, blotched and barred reddish-brown.6 A geographic race is reported 36 which has a brown border on the otherwise normal yellow coloured lip, now described as subspecies marginatum.

Onc. caloglossum is thought by some to be perhaps a subspecies of gardneri and is listed as a synonym for pectorale by Garay and Stacy.2 Fowlie,37 however, lists this as a separate species. 'Lost' for many years, Williams7 describes it as producing about 30 flowers. The petals and sepals are yellow striped with sepia-brown, those on the petals being remarkably confluent; the lip is brighter yellow with brown blotches in front. Found growing on saplings and lianas 3 to 7 metres above the ground, its roots run up and down the bark, these giving its hiding place away, enabling it to be easily discovered. It commences growth in the early Brazilian spring following the onset of the rains, and flowers from the fresh pseudobulb without any resting period in the early summer (December to January). After flowering, in the early autumn, it throws rapidly elongating roots for a considerable distance along its host plant.37

Onc. curtum is closely related to praetextum, this one however having smaller flowers, and shows differences in the details of the crest. Occurring on the leeward side of the Organ Mountains in the Serra do Mar and Serra Paranapiacaba at an elevation of I,100 to 1,200 metres above sea level, it was named in deference to its short stature at flowering, and low scape of flowers, as compared to other speoies of this Section. The pseudobulbs are somewhat gimilar to those of praetextum, although often appear more withered than other species of this group. The flower scape is 300 to 450 mm long, bearing 12 to 18 flowers, each some 30 to 35 mm in diameter. These appear in mid summer (January).34

Onc. gardneri is reported to grow naturally over a wide area occurring from at least the Serra do Mar through the Serra do Bocaina to the Organ Mountains. The original collections were made from the Organ Mountains by Gardner, the plants being first described by Lindley in 1843.34

Oncidium gardneri

It was once considered a natural hybrid between dastyle. and forbesii6. It has dark green to light red-brown pseudobulbs which are 50 to 75 mm high, 25 to 35 mm wide, covered by a white powder as found on some other species of this Section. There is a pair of leaves 150 to 200 mm long, and the flowers are about 50 mm in diameter, the sepals brown, barred yellow, the petals much larger, chestnut brown with numerous yellow markings down the margins. The lip is spreading, fan shaped, yellow with red-brown basal markings, the mid lobe bright yellow with a broad zone of red-brown spots near the undulating margins.' The species flowers in the early Brazilian summer, from about mid December through to February. Flowers are 25 - 35 mm in diameter, about 8 to 24 on a compound spray which is some 300 to 450 mm long.34

Onc. duveenii is a recently discovered species which flowers in February, and is found growing some 1100 metres above sea level. Closely related to forbesii, it has but a single leaf. It has a divided mid lobe, coloured bright chrome yellow, the lateral auricles and differing callosity make it distinctive from forbesii. The scape is a lax panicle 200 to 350 mm long, bearing 3 to 8 flowers.36

Onc. forbesii is a quite well known species which flowers in the Brazilian autumn, usually from February to April. The first plants were discovered by Gardner in the Organ Mountains in 1837. Sent to the Duke of Bedford in England, it was cultivated and brought into flower by Mr Forbes, horticulturalist of the Duke's collection at Woburn Abbey. It was first flowered in cultivation in 1838, being described and named in 1839 by Hooker.34

It is found over a quite widespread area in Brazil, from the Serra da Extrema, the Organ Mountains to Espirito Santo. It is also in the Serra do Mar and northwards to the Serra da Bociana.34 Generally it is found growing in the foggy forests on the leeward slopes at around 900 to 1,200 metres above sea level, and is said not to enjoy dry zones.34

Oncidium forbesii

Oncidium intergeneric (Oncidium forbesii X Odontoglossum bictoniense)

The pseudobulbs are 50 to 75 mm high, Hawkesl stating the plant has two leathery dark green leaves 150 to 300 mm long. Fowlie34 however, describes a single apical leaf, although reports a large flowered race with two leaves. The inflorescence is erect or arching, to one metre tall, comprising a rather many flowered panicle. Its flowers are 65 mm in diameter, all segments vivid chestnut-brown with a narrow yellow border.1 There are 6 to 14 flowers on the panicle, which is 300 to 400 mm long. Because there are often flecks of gold colouration on the margins of the tepals, it is often given the common name of the "Gold Laced Oncidium".34

Onc. enderianum flowers in the late autumn, February to April,34 and was originally considered a natural hybrid between crispum and curtum 6. This species has perhaps the most widespread distribution of the Cnspa Section.34 It is found from Santa Catarina, Bananal, Organ Mountains, Serra da Espinhaco to the Espirito Santo.39 An interesting series of discussions which highlights the taxonomical confusion surrounding some of the Crispa Section species involving this species appears in the AOS Bulletin 1978 47:1 pp. 51 - 52 and 47:6 pp 496 - 498, and Orchid Digest.39

It produces pseudobulbs 35 to 75 mm high, 25 to 35 mm wide, having two apical leaves 175 to 300 mm long. It grows under similar conditions to crispum, flowering on a panicle 300 to 450 mm high. It bears 8 to 16, 35 to 50 mm wide flowers, producing an odour of sweetness, sometimes likened to lilac.34 Sometimes described and sold as a 'small sized crispum' its later flowering period, more rounded petals, smaller flowers and different callus establishes its separate identity. It is found growing some 1,000 metres above sea level.34

Onc. gravesianum is one of the last of this Section to flower, this occurring in the late autumn to early winter, in the months of April to June. This species was not discovered until 1892. The pseudobulbs are 65 to 75 mm high,50 to 65 mm wide, having a distinctive purplish suffused brown colouration. Leaves are 100 to 200 mm long, usually two, but sometimes three. The flowering scape is 300 to 450 mm high, bearing 8 to 16 flowers, which are each up to 50 mm wide, having a deep chocolate brown colour, speckled faintly and irregularly with yellow. The petals are narrow and ungainly as compared with the other species of this Section. The lip is rounded with a small end notch, again chocolate-brown except the base which is a vivid yellow.34

This species is found in Pernambuco. It is closely related only to enderianum, this species having reduced side lobes, diminished column wings, and different odour to gravesianum. It is also said to grow over a distinct geographic range.39

Onc. zappii, a very recent discovery, was only described in 1976. Found in the Espirito Santo, it has a single leaf like forbesii, and is described as autumn flowering, although other details of this species are unknown. It is illustrated with a coloured photograph by Fowlie36 on page 166 of his article.

Oncidium sarcodes

In addition to the species noted above, Garay and Stacy2 additionally list chrysopterum, litum, macropetallum, pardoglossum, riviereanum. tarcodes, stanleyi and wheatleyanum. One of these later species is quite widely grown - sarcodes—a worthwhile addition to most collections. Williams6 notes this is "a remarkably fine species, producing its showy and handsome flowers during September and October". Introduced into cultivation in 1849, it comes from the Organ Mountains of Brazil. The name 'sarcodes' meaning 'flesh-like' refers to the red-brown colour of the 30-50 mm flowers. These are produced on a many flowered panicle 3 - 5 feet 1ong,6

Moden intergeneric hybrid using Crispa species
Odonticidium
((Odm. bictoniense X Odcdm. Dena Reinikka) X Onc. marshallianum)

CULTURAL REQUIREMENTS

The plants in the main come from the coastal regions of Brazil, the monsoonal foothill mountain habitat.. The ranges of mountains run parallel with the coastline, extending both north and south of Rio de Janiero, with some species coming from further inland in the Serro do Espenhaco. The moisture-laden winds coming inland from the sea, are forced upwards by the mountains. This chills the air and the moisture precipitates out in large clouds around the summits of the mountains. On the leeward side the air is less heavily moisture laden, although humidity never falls below 65%. During the winter months, the sky is clear and blue, and there is less moisture in the air. The light levels are also higher, as some of the trees are deciduous, although light intensity does not reach high levels because the sun will be lower in the sky at this time of the year. The plants receive therefore relatively bright cool dry conditions over the winter months, a period when all growth virtually ceases.


In the spring, frequent rains and mists course through the habitats of these orchids. While the sun will naturally be higher in the sky, giving increased light, the greater cloud cover and increased amount of leaf on surrounding vegetation provides some increased shade. During the cool dry winter, the plants are torpid and inactive. With the spring rains, a new eye is broken, and the new growth develops and matures at an incredible speed. The first flowering species do not fully mature their new pseudobulbs when the flower scape appears; the later flowering species will go through some dormancy between making up the new pseudobulbs and producing flowers. After flowering is completed, extensive root proliferation and elongation takes place, before all growth ceases at the onset of winter.36

A description of the typical environment of praetextum already noted will also indicate {certain requirements to be considered in the culture of these plants.

Against the background of this information, the specific cultural elements will now be discussed.


TEMPERATURE


The change from cool dry to a warm moist period is indicated by the seasonal conditions naturally experienced. The Dictionary of Gardening6 states a winter temperature of 10 oC, or even lower, should be maintained, increased to subtropical during the period of active growth.6

Fowlie38 has taken careful temperature measurements on the windward side of the Organ Mountains, and these have shown temperatures have varied from a low of 3 oC, or even lower, on cold clear winter nights, to a high of 29 oC in the shade on hot sunny summer days.

Hawkes l and The Dictionary of Cardening6 both show the listed species as being cool growers, although the higher temperature growing period requirements should be noted.


GROWING MEDIA

Fowlie38 states the plants will not thrive on tree fern, and observes they should be cultured on cork bark, or better, on cork oak limbs. My own experience shows that they grow strongly and flower well on tree fern, (Dicksonia) provided a relatively high level of humidity is maintained when growing. Because of their considerable 'fetch' of roots during their growth cycle, long mounts of up to 1.3 metres are suggested, because if space for the roots is not provided for, subsequent flowering can be affected. The plants should be placed at the top of the mount; the pseudobulbs are close together, and this leaves plenty of room for the roots to grow.

Schaffer11 notes that the well known oncidiinae grower W.W.G. Moir of Hawaii believes that it does not matter what the media is, as long as it dries well, aerates well, keeps free from fungus and scum, and dries out well between waterings. The scarcity of cork oak limbs in this country will require other media to be used, and it is relevant to note that Hawkes l states that the plants will grow successfully in most media, provided perfect drainage is available. They are highly intolerant of stale conditions around their roots.


WATERING, HUMIDITY AND AIR


During the winter, little or no water should be given, as this is the period of dormancy. As soon as the new growth commences, heavy watering should be provided for. Humidity naturally never falls below 65%, and is usually around 85% during the main growing season, the winters being the driest. This should be kept in mind when we grow the plants in our glasshouses.38 Plenty of fresh moving air also seems to be an essential requirement for the successful culture of these plants, and to maintain them in good condition free frorn rbt and diseases.


SHADING


During the winter, the plants should be exposed to direct sunlight. During growth during summer, some shading may be necessary, although most growers recommend that the plants respond to fairly bright conditions being given the plants the whole year, which is my experience; especially when moisture and good air flow can be provided.


FERTILISERS


Most authorities agree that some fertiliser applications are beneficial, although, as applies with all epiphytes, dilute applications only should be provided. Strengths of one quarter to one half of a manufacturer's general dilution recommendations should be utilised. Hawkes1 advises all oncidiums benefit from regular and liberal applications of fertiliser, although excessive applications to certain of the more robust species may result in lush vegetative growth being produced, but with few flowers.


Moir 8 notes that the square flowering species crispum, forbesii and enderianum and the longer shaped marshallianum are valuable in breeding. They have been often combined with the Synsepala species, especially Onc. varicosum, this species, however, usually being dominant.


With the species and their hybrids producing quite spectacular flowers which are quite long lasting, their culture is worthwhile, notwithstanding that they can take up quite a lot of space, especially when grown to specimen size.

FURTHER INFORMATION


Seasonal oncidium culture on a generalised basis is also available on this site, as is a table showing the floweirng times of the crispa oncidiums species.

Remember, growing orchids is all about enjoying your plants
and sharing your growing success with friends and family.

Good luck and good growing.

   
   



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