Caladenia longicauda is a species of plant in the orchid family Orchidaceae and is endemic to the south-west of Western Australia. It is distinguished by its large leaf and by its up to five large, white flowers which have drooping sepals and petals with long, thickish brown "tails".
Caladenia longicauda is a terrestrial, perennial, deciduous, herb with an underground tuber and a single hairy leaf, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide. Between July and early November it produces one to three (sometimes up to five) flowers on a stalk NaNsigfig=1NaNsigfig=1 tall, each flower NaNsigfig=1NaNsigfig=1 wide. The flowers are mostly white except for a few red markings and reddish stripes on the backs of the petals and sepals. The dorsal sepal is green, erect, NaNsigfig=1NaNsigfig=1 long and NaNsigfig=1NaNsigfig=1 wide with its edges slightly turned inwards. The lateral sepals are NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide, spreading horizontally near their bases but then drooping. The petals are similar to the sepals but slightly shorter and narrower. The labellum is white, NaNsigfig=1NaNsigfig=1 long, NaNsigfig=1NaNsigfig=1 wide with erect to spreading teeth up to 10sigfig=1NaNsigfig=1 long along its sides. The middle part of the labellum has the longest teeth on its edge. These teeth are red with hooked white tips. The front part of the labellum curves downwards, with the teeth becoming shorter. There are between four and eight rows of calli along the central part of the labellum, the calli pale to dark red and club-shaped. The fruit is a non-fleshy, dehiscent capsule containing a large number of seeds.[1] [2] [3]
Caladenia longicauda was first formally described by John Lindley in 1840 and the description was published in A Sketch of the Vegetation of the Swan River Colony.[4] The specific epithet (longicauda) is derived from the Latin words longus meaning "long" and cauda meaning "tail".[5]
The names of fourteen subspecies of C. longicauda are accepted by the Australian Plant Census:[6]
| Subspecies | Description | Distribution and habitat | Image |
|---|---|---|---|
| Lateral sepals long, labellum wide | |||
| C. longicauda subsp. albella Hopper & A.P.Br. (small-lipped spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. australora Hopper & A.P.Br. (southern white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. borealis Hopper & A.P.Br. (daddy-long-legs spider orchid | Lateral sepals long, labellum wide | Shrubland between Cataby and Kalbarri | |
| C. longicauda subsp. calcigena Hopper & A.P.Br. (Coastal white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. clivicola Hopper & A.P.Br. (Hill's white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. crassa Hopper & A.P.Br. (Esperance white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. eminens (Domin) Hopper & A.P.Br. (stark white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. extrema A.P.Br. & G.Brockman | Lateral sepals long, labellum wide | Winter-wet areas near Manjimup[7] | |
| C. longicauda subsp. insularis Hopper & A.P.Br. ex A.P.Br. & G.Brockman | Lateral sepals long, labellum wide | Coastal heath near Esperance[8] | |
| C. longicauda subsp. merrittii Hopper & A.P.Br. (Merritt's white spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. minima A.P.Br. & G.Brockman | Lateral sepals long, labellum wide | ||
| Caladenia longicauda subsp. redacta Hopper & A.P.Br. (tangled spider orchid) | Lateral sepals long, labellum wide | ||
| C. longicauda subsp. rigidula Hopper & A.P.Br. (rigid spider orchid) | Lateral sepals long, labellum wide | ||
Caladenia longicauda grows in a wide range of habitats from the Kalbarri National Park on the west coast to Israelite Bay on the south coast.
Most subspecies of C. longicauda are classified as "Not Threatened" but subspecies extrema and insularis are classified as "Priority One" by the Western Australian Government Department of Parks and Wildlife meaning that they are known from only one or a few locations which are potentially at risk.[9] Subspecies minima is classified as "Priority Two", meaning that it is poorly known and from only one or a few locations.