Australian Dendrobium Orchid Species- overview

Transcription

1 Australian Dendrobium Orchid Species- overview Introduction Australia has over 56 native Dendrobium species although recently an alternative naming system has been proposed that has reclassified Dendrobium species into other genera and species. The new Genera include Cadetia, Cepobaculum, Ceratobium, Coelandria, Davejonesia, Dockdrillia, Durabaculum, Flickingeria, Tetrabaculum, Thelychiton, Tropilis and Vappodes. As this renaming is not universally accepted or resolved, for the purpose of this overview the original names will be used as well as the new proposed names. Refer to the species articles on this web site for more detailed growing guides for the different species. Dendrobium speciosum complex or Thelychiton species Thelychiton spp. or syn. Dendobium speciosum Commonly known as rock orchids or rock lilies they can be found along the east coast of Australia (see maps below). There are a great variety of vegetative forms within Den. speciosum that vary in stature from short to very tall. It has been proposed that the Den. speciosum complex be divided into 6 Thelychiton species although this is not universally accepted at this stage so both names are used. The 6 species (or Dendrobium varieties) are summarised below based on their natural distribution starting with most northerly species first and progressively moving south. Thelychiton pedunculatus (syn. Den. speciosum var. pedunculatum). This species has a restricted distribution of about 100km on the west of the Atherton Tablelands in Queensland (10) in an area that has a long dry winter period. It is a dwarf form with pseudobulbs usually not exceeding 25cm long. It has thick upright leaves. The plant must tolerate a dry winter period lasting several months. It gets its name from the very long peduncle between the leaf axil and the start of the flowers on the raceme. Over half the raceme length will have no flowers. Racemes can be up to 75 cm long but are usually much shorter. Flower colour is mostly white, cream or pale yellow (10). Breeders have used this species extensively to incorporate its dwarf character. Thelychiton curvicaulis (syn. Den. speciosum var. curvicaule). This species has a limited range and grows from mid way between Rockhampton and Mackay north to Airlie Beach (10) at elevations of 20 to 1200m. Pseudobulbs are very long and thick and measure up to 85 cm to the first leaf and it usually only has 2 or 3 thick leathery leaves. Plants from higher elevations have the largest pseudobulbs and longer racemes. This species does not produce aerial roots. Flower colour is white through to pale yellow. Selections include Eungella Dawn, Fab and Eungella Queen.

2 Thelychiton capricornicus (syn. Den. speciosum var. capricornicum). This species is found north of Rockhampton in central Queensland around the Tropic of Capricorn, below which T. rex is more common (10). It is more commonly found on rocks rather than trees (10). Pseudobulbs vary from 15 to 35cm long and are not very thick with relatively small leaves. The clone Big Boy is highly awarded but this species is not widely grown. Flower colour ranges from pale yellow to off white with racemes up to 60cm long. Thelychiton rex (syn. Den. speciosum var. grandiflorum) This form is similar in appearance to T. tarberi (see below). It and T. tarberi are the only vars of speciosum to have aerial roots (10). Its common name is the Golden King Orchid. Flower colour is mid to dark yellow and flowers are larger than found on T. tarberi. Racemes can be up to 75cm long by 15 cm in dia (10). It grows on rocks and trees and is predominantly found around Kingaroy and Gympie north to Rockhampton in Qld at elevations of 100 to 600m (10). Thelychiton tarberi (syn. Den speciosum var. hillii). This species, sometimes referred to as the Tree King Orchid or the Pale King Orchid, is found 200 km north of Sydney and its northern limit is near Nambour 100km north of Brisbane in Queensland (10). It grows at elevations of 50 to 1200m as an epiphyte in rainforests or humid forests (11) on trees or rocks. Pseudobulbs are thin, long and tapered and up to 1m long with many aerial roots. Racemes can be up to 60cm long with up to 400 flowers per raceme. Flowers are about 25mm wide and typically pale cream or white with no yellow flowers known (10). It is not as popular as other speciosum species with growers. Thelychiton speciosus (syn. Den. speciosum) This is the most southerly species and is commonly called the NSW Rock Lily and grows from Victoria to the central coast of NSW from sea level to around 900m (10). It predominantly grows on rocks and very occasionally on trees (10). Pseudobulbs range in length from 15 to 75 cm with 2 to 5 leaves up to 30cm long and 8cm wide. Racemes can be up to 60cm long with flower colour ranging from white to strong yellow (10). It flowers from September to November. Not all plants flower each year. Two well known cultivars are Windemere and National White Thelychiton epiphyticus This epiphyte, commonly known as the Illawarra rock orchid, is only found in southern NSW in the Nowra district. It only grows on trees and has up to 50 cream flowers per raceme compared to T. speciousus which has up to 100 flowers per raceme (13).

3 General comments Many plants only flower well every second year and require good exposure to sunlight to flower. Flowers can be very strongly perfumed. Flowering is concentrated in late winterspring. They can bloom off the same pseudobulbs for a number of seasons (2). T. speciosus has been used in extensive crossing and selection programs to produce a wide variety in flower colours and strong thick pseudobulbs. Seedlings can take up to 10 years to flower (4). Hybrids of D. speciosum with either D. falcorostrum or D. kingianum in their parentage flower more reliably each year on smaller younger plants (4). As a lithophyte, it can produce large spreading clumps on rocks and cliff faces, often in full sun, with its roots forming a dense mat across the rock. To better understand the natural distribution of Dendrobium speciosum varieties (or syn. Thelychitons), the map below describes the distribution of the various 9 varieties based on the original Dendrobium speciosum classification (12). These 9 speciosum varieties have now been renamed as unique Thelychiton species in the proposed reclassification. To further complicate the classification, it is now been proposed there is only one speciosum with a northern (found north of Mackay) and southern sub species (found south of Mackay down to eastern Victoria) (14). Map showing distribution of 9 Dendrobium speciosum varieties based on the older classification (From Adams et al. 2006)

4 Other Thelychitons or syn Dendrobiums Thelychiton falcorostrus or syn. Dendrobium falcorostrum A white flowering epiphytic species originating in the rainforests of Queensland and New South Wales and tolerates temperatures down to freezing. Also known as the Antarctic Beech Orchid. Stems grow up to 50cm long. Grows on Beech trees in cool temperate rainforest north of Bardo Rose Barrington Tops in NSW. The white flowers are strongly perfumed. Bardo Rose is very popular fragrant primary hybrid of Den. falcorostrum and Den. kingianum. Thelychiton fleckeri or syn. Dendrobium fleckeri This species known as the apricot cane orchid has apricot coloured flowers. Many hybrids have been made with this species. Pseudobulbs are up to 40cm long. Found growing in cloud forests on trees and boulders, often amongst moss. Flowers August to January. Thelychiton kingianus or syn. Dendrobium kingianum A very hardy orchid with colours ranging from dark purple to pale pink. It can be found from central NSW to the Carnarvon Gorge in Queensland. Canes are shorter in the more southern forms and more elongated in more northerly warmer climate forms. It has been widely used in crossing programs to develop hybrids with over a 1000 registered forms. Colours range from white to pink and dark purple. Some cultivars carry 2 racemes per cane. It is more prone to frost than other Dendrobiums and also more likely to produce keikis if given too much nitrogen fertilizer. Dendrobium delicatum This easy to grow lithophytic species is a natural hybrid of D. kingianum and D. tarberi found in eastern NSW to north Queensland (2). Its pseudobulbs can be up to 35cm long with 2 to 5 leaves at the top. It requires plenty of sun to flower and a dry winter. It flowers from late winter to spring. Flower colours range from white to pink with a large range of cultivars available (see Santa Barbara Orchid Estate web site) (6). Tetrabaculum This genus contains species from the old Dendrobium tetragonum complex. Commonly known as the spider orchid. There are 4 varieties of Den. tetragonum (5), Var. melaleucaphilum with the common name Spider Orchid is found from the Blue Mountains in NSW to central Queensland. It is an epiphyte that grows mainly on Melaleuca trees. Var. tetragonum, grows from the Illawarra region in NSW to the Fitzroy River in Queensland and is known as the blotched tree spider orchid due to the shape of the flowers. It is found at altitudes of 500 to 1200m. Var. cacatua is a tropical form that is found between the Fitzroy and Annan Thelychiton fleckeri Thelychiton kingianus Den. delicatum Den. tetragonum

5 Rivers in Queensland. Its common name is Yellow tree spider orchid and is commonly found in dense rainforests on trees in shady areas beside streams. It flowers from July to September. Pseudobulbs are narrow, pendulous and up to 50cm long with 2-5 leaves. Var. giganteum is a tropical form found from the Fitzroy River north to the Cape York Peninsula in Queensland at elevations from sea level to 900m in shady locations on trees beside streams. This variety has larger flowers up to 12cm across which are yellow with white lip blotched with red (9). A further 2 varieties of tetrabaculum have been recently classified, var serpentis and subspp cataractarum. Flowers are spidery in appearance with a pseudobulb producing flowers for many years. These epiphytes are best grown on mounts with moss over their roots under high humidity. Hybrids produced from Den. tetragonum include; D. speciosum x D. tetragonum = D. Hilda Poxon D. falcorostrum x D. tetragonum = D. Star of Gold D. kingianum x D. tetragonum = D. Ellen See the article by Issy Klein listed below for a fuller description of the hybrids (5). Vappodes Australian species in this group come from warmer more northern regions of Queensland and generally require warmer temperatures with minimum night temperatures of 15 C, daily watering in summer but a dry winter period. They are best grown on a mount in a glasshouse. The better known species include: Vappodes bigibba syn. Den. bigibbum. (pronounced bi-gib-ba and bi-gibb-um). This species, also known as the Mauve Butterfly Orchid, occurs from northern Queensland to the Torres Straight Islands (8). Pseudobulbs can be very long up to 120cm long with 3-5 leaves. It flowers from February to July. This species is a grandparent in the breeding of Den. Anne s Rainbow surprise and Den. Jonathan s Glory which have both been highly awarded (4). Vappodes lithocola syn, Den. bigibbum var. compactum. (pronounced bi-gibb-um). This species occurs between the Daintree and Cairns in NE Queensland and is commonly called the Dwarf Butterfly Orchid. It occurs at 250 to 800masl in high rainfall areas (7). Pseudobulbs can be up to 25cm long with 3-4 terminal leaves. Racemes have 2-20 flowers. Plants are often found exposed to full sun on rocks and cliff faces and hot dry conditions when they completely defoliate. They flower from March to October. Flowers can be lilac purple, white, bluish or pink (7). Vappodes phalaenopsis, syn. Den. bigibbum var. superbum. (pronounced bi-gibb-um). Also known as the Cooktown Orchid (see Dendrobium phalaenopsis fact sheet on this web site for more growing hints). This hard-cane evergreen species is native to the Cape York area of far North Queensland. It has been used in crosses with cool growing dendrobiums to produce hot-cold hybrids. Cooktown orchid

6 Hot-cold hybrids New hybrids have been produced to give larger and more colourful flowers. These typically are crosses using D. kingianum, D. speciosum, D. tetragonum and Vappodes species. If tropical species have been used in the parentage, more warmth will need to be given in winter, otherwise they will tolerate similar cool conditions as speciosus. Other Dendrobium/Thelychiton species. Hybrid Dendrobium A more detailed description of these and other Australian Dendrobium (Thelychiton) species and their cultural requirements can be found in the references listed below. Further reading These notes are based on information provided by local growers and the references below. 1. Growing Orchids in Cool Climate Australia (second edition) by M J Fraser, J Wright, W Ferris (2013). 2. Gardening Australia Flora s Orchids. ABC Books (2005). 3. Australian Dendrobiums and their Cultivation. by A Hope How I Grow Australian Dendrobiums (and Dockrillias) by B Milligan The influence of Dendrobium tetragonum in Australian Native Dendrobium Hybridising by Issy Klein Santa Barbara Orchid Estate. llection_short_name=aussie%20hybrids&collection_name=australian%20dendrobiu m%20hybrids 7. Australian tropical rainforest Orchids. Vappodes lithocola by MA Clements and DL Jones e0e/media/Html/Vappodes_lithocola.htm 8. Australian Tropical Rainforest Orchids. Vappodes bigibba. By MA Clements and DL Jones e0e/media/Html/Vappodes_bigibba.htm 9. Dendrobium tetragonum The Rock Lily Man Dendrobium tarberi. M Clements and D Jones PB. Adams, JM. Burke and SD. Lawson (2006). A review of the taxonomy and relationships of the Dendrobium speciosum complex (Orchidaceae), and recognition of two new taxa. Telopea. 13. Orchid species of the Shoalhaven by Alan Stephenson. (2011). 14. Wet tropics a critical refuge for Australia s rock orchid by L. Simpson. Australian Orchid Review Vol 82 (6). Your comments and suggestions on cultural guide are welcome. your comments to dearconsultingservices@gmail.com Updated 7/05/18

7 These notes are intended as a guide only and are composed from available information and local experience.the Wagga Wagga Orchid Society and its members are not responsible for any loss or damage.