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White Primrose Orchid
Caladenia lateritica K.W.Dixon & Christenh. 2018

Synonyms

Notes

Restricted to a small area of south-western WA, the White Primrose Orchid looks almost exactly like the common and widespread Cowslip Orchid (Caladenia flava) except for being white instead of yellow in colour. Like the Cowslip Orchid, it usually features maroon or pink stripes and spots on its petals and dorsal sepal. In fact, it looks exactly like the occasionally encountered white colour form of the Cowslip Orchid, but forms almost pure populations in areas where the regular yellow form of the Cowslip Orchid is less abundant.

The White Primrose Orchid is restricted to a small area of the Darling Scarp south of Perth where it grows in lateritic soil (hence the scientific name lateritica) in open Jarrah–Marri woodland and is typically very common. Curiously, it forms almost pure populations which largely replace the normal yellow form of the Cowslip Orchid. As the White Primrose Orchid does not produce nectar, both its colour and scent are believed to mimic the co-occurring White Cottonhead (Conostylis setosa) as a way of attracting pollinators. This appears to provide an ecological advantage over the standard yellow flower colour of the Cowslip Orchid.

While the White Primrose Orchid has been described as a separate species, its exact status is uncertain, and it is more likely to be simply a white colour form of Caladenia flava which has evolved to fill a specific ecological niche. Some flowers still show some yellow colouration which also points to the Cowslip Orchid as its ancestor. Interestingly, it grows in the company of another Cowslip Orchid look-alike, the Pink Primrose Orchid (Caladenia rosea), which has pink instead of yellow or white flowers and could likewise simply be an unusual colour form of the Cowslip Orchid.

Photos

Caladenia lateritica
The flowers are similar to those of the Cowslip Orchid (Caladenia flava), but are mostly white instead of yellow. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
In fact, they look exactly like the white colour morphs of Caladenia flava which are occasionally encountered. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
The pattern of pink lines and spots is highly variable and can be missing entirely in some specimens. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
View of the entire plant. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
Some specimens feature extensive pink colouration and can be difficult to separate from the Pink Primrose Orchid (Caladenia rosea). (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
Others have preserved some of the original yellow colour of the Cowslip Orchid (Caladenia flava). (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
Close-up view of the labellum. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
The flowers are thought to mimic the co-occurring White Cottonhead (Conostylis setosa) in both colour and scent. (Teesdale, WA, 17 / 09 / 2023)
Caladenia lateritica
The White Primrose Orchid grows in lateritic soil in open Jarrah–Marri woodland in a restricted area of the Darling Scarp. (Teesdale, WA, 17 / 09 / 2023)

References