Caladenia

Spider orchid
C. carnea, the type species of Caladenia
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Monocots
Order:	Asparagales
Family:	Orchidaceae
Subfamily:	Orchidoideae
Tribe:	Diurideae
Subtribe:	Caladeniinae
Alliance:	Caladenia
Genus:	Caladenia R.Br., 1810
Type species
Caladenia carnea R.Br. Prodr.: 324, 1810
Synonyms[1]
Petalochilus R.S.Rogers Arachnorchis D.L.Jones & M.A.Clem. Calonemorchis Szlach. Drakonorchis (Hopper & A.P.Br.) D.L.Jones & M.A.Clem. Jonesiopsis Szlach. Phlebochilus (Benth.) Szlach. Stegostyla D.L.Jones & M.A.Clem. Caladeniastrum (Szlach.) Szlach.

The genus Caladenia, commonly known as the spider orchid, belongs to the subfamily Orchidoideae of the orchid family (Orchidaceae). The abbreviation Calda. is often used in trade journals to indicate the genus.

The subtribe Caladeniinae is considered polyphyletic, due to the alliance of Lyperanthus with the genera of Drakaeinae and Thelymitrinae.

Description

Cowslip orchid
(Caladenia flava subsp. flava)

The scientific name is derived from the Greek words calos (meaning beautiful) and aden (meaning glands), referring to the colourful labellum and the glistening glands at the base of the column that adorn many of the species.

The genus was described by Robert Brown in 1810 from specimens that he sighted in most Australian states, as a member of Matthew Flinders' mapping and exploration voyage that circumnavigated Australia. Brown, with assistants, spent just over three years in Australia on botanical research.

The species are small to medium-sized terrestrial orchids. A single, hairy, lanceolate to oblong, basal leaf arises through sympodial growth from underground tubers. The inflorescence is a panicle or raceme with 1 to 8 flowers, showing a fringed or dentate margin. These species have a complex interaction with pollinators, resulting in pseudocopulation.

They are mostly Australian and are from its southern areas. There are four species in New Zealand and another extends to New Caledonia, Indonesia and Malaysia. The south west corner of Western Australia contains the most spectacular and numerous species, varieties and natural hybrids. The huge variation of form and colour of the species leads to a bewildering array and abundance of hybrids. Many are morphologically difficult to separate with some defying separation at present.

Recent taxonomy revisions have, apparently, largely increased the number of species to more than 300 and split the genus into separate groups. For example, Caladenia filamentosa has been split into about 40 different species and subspecies, while a number of subspecies have been upgraded to the status of species (such as Caladenia fragrantissima subsp. orientalis to Caladenia orientalis). This further complicates the issues of identification. For example, Caladena ericksonea is, a naturally occurring hybrid of Caladena doutchiae and the red Caladena filamentosa and also of the hybrid of Caladena cairnsiana and the red Caladena filamentosa.

Whilst colour is an unreliable guide to identification with hybrids, it comes through strongly from one parent or the other for most hybrids whatever the parent species

Caladenia have generally proven difficult to maintain and cultivate artificially with those removed from their habitat rarely surviving more than a few years. The clumping of many of the species could be a result of tuber division or it could be because the seeds fall at the base of their parents and grow there.

The galleries demonstrate the huge variation within colonies and phytogeographic variation over the range north to south and east to west with ever changing climatic and habitat situations over the 150,000 km² of the south west of Western Australia.

Species

Arrowsmith Spider Orchid
(Caladenia crebra)

Caladenia longicauda subsp. borealis

Caladenia chlorostyla, one of the species endemic to New Zealand

Several Caladenia species from Pelloe's West Australia Orchids

There 243 species (as of 2005) and six subgenera.

Natural hybrids

• Caladenia × aestantha Hopper & A.P.Br. 2001 (C. corynephora × C. serotina) (synonym : Arachnorchis x aestantha (Hopper & A.P.Br.) D.L.Jones & M.A.Clem, 2005)
• Caladenia × cala Hopper & A.P.Br. 2001 (C. falcata × C. longicauda) (synonym : Arachnorchis x cala (Hopper & A.P.Br.) D.L.Jones & M.A.Clem 2005)
• Caladenia × coactescens Hopper & A.P.Br. 2001 (C. crebra × C. longicauda) (synonym : Arachnorchis x coactescens (Hopper & A.P.Br.) D.L.Jones & M.A.Clem 2005)
• Caladenia × eludens Hopper & A.P.Br. 2001 (C. chapmanii × C. splendens)
• Caladenia × enigma Hopper & A.P.Br. 2001 (C. barbarossa × C. longicauda)
• Caladenia × ericksonae Nicholls 1950 (C. cairnsiana × C. filifera)
• Caladenia × erminea Hopper & A.P.Br. 2001 (C. flava × C. marginata)
• Caladenia × exoleta Hopper & A.P.Br. 2001 (C. dimidia × C. roei)
• Caladenia × exserta Hopper & A.P.Br. 2001 (C. longicauda × C. uliginosa) (synonym : Arachnorchis x exserta (Hopper & A.P.Br.) D.L.Jones & M.A.Clem 2005)
• Caladenia × hypata Hopper & A.P.Br. 2001 (C. lobata × C. longicauda) (synonym : Arachnorchis x hypata (Hopper & A.P.Br.) D.L.Jones & M.A.Clem 2005)
• Caladenia × idiastes Hopper & A.P.Br. 2001 (C. gardneri × C. latifolia)
• Caladenia × lavandulacea R.S.Rogers 1927 (C. denticulata × C. doutchiae)
• Caladenia × ornata Hopper & A.P.Br. 2001 (C. drakeoides × C. exilis)
• Caladenia × resupina Hopper & A.P.Br. 2001 (C. horistes × C. multiclavia)
• Caladenia × spectabilis Hopper & A.P.Br. 2001 (C. flava × C. latifolia)
• Caladenia × suffusa Hopper & A.P.Br. 2001 (C. hirta × C. longicauda) (synonym : Arachnorchis x suffusa (Hopper & A.P.Br.) D.L.Jones & M.A.Clem 2005)
• Caladenia × triangularis R.S.Rogers 1927 (C. flava × C. longicauda)
• Caladenia × tryphera Hopper & A.P.Br. 2001 (C. microchila × C. sigmoidea)
• Caladenia × variabilis Nicholls 1950 (C. cardiochila × C. fragrantissima)

Intergeneric hybrid

• xCalassodia (Caladenia x Glossodia)

References

• Stephen D. Hopper and Andrew P. Brown (2004). "Robert Brown's Caladenia revisited, including a revision of its sister genera Cyanicula, Ericksonella and Pheladenia (Caladeniinae: Orchidaceae)". Australian Systematic Botany 17 (2): 171–240. doi:10.1071/SB03002. 
• New species in Orchid Research Newsletter No. 47 (January 2006) (Royal Botanical Gardens, Kew)

External links

Wikimedia Commons has media related to Caladenia.

• Gallery of images - Orchid Society of Western Australia