''Caladenia actensis'', commonly known as the Canberra spider orchid, is a plant in the orchid family

Orchidaceae Orchids are plants that belong to the family Orchidaceae (), a diverse and widespread group of flowering plants with blooms that are often colourful and fragrant. Along with the Asteraceae, they are one of the two largest families of flowering ...

and is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the

Australian Capital Territory The Australian Capital Territory (commonly abbreviated as ACT), known as the Federal Capital Territory (FCT) until 1938, is a landlocked federal territory of Australia containing the national capital Canberra and some surrounding townships. ...

. It has a single leaf and usually only one greenish flower with red markings and only occurs in three small populations.

Description

''Caladenia actensis'' is a terrestrial,

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal ...

with an underground tuber and which grows singly or in small groups. A single leaf, long and wide appears in late autumn or early winter, after rain. Usually only a single flower is borne on a stalk tall. The flower is greenish, heavily marked with reddish-crimson lines and blotches, and is wide. The dorsal

sepal A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106 The term ''sepalum'' was coined b ...

is erect, long and about wide while the lateral sepals are a similar size but are turned downwards, close to the ovary. The

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s are long and wide. The labellum is heart-shaped, wide and wide and maroon or green with a maroon tip. The labellum curves forward and downwards and there are up to six pairs of short, blunt teeth on its sides. The mid-line of the labellum has four to six rows of crowded dark, purplish-red calli. Flowering occurs from late September to mid- October.

Taxonomy and naming

''Caladenia actensis'' was first formally described by David L. Jones and Mark Clements in 1999 and the description was published in ''The Orchadian'' from a specimen collected on Mount Ainslie. The

specific epithet In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...

(actensis) is derived from the abbreviation of Australian Capital Territory (act) with the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

ending "-ensis" meaning "of" or "in", hence "of the Australian Capital Territory".

Distribution and habitat

Canberra spider orchid occurs in three small scattered populations on Mount Majura, Mount Ainslie and in the Madura Valley. It grows in the transitional zone between woodland and forest, with grasses and small shrubs, often amongst rocks.

Ecology

As with other caladenias, this orchid requires a

mycorrhiza A mycorrhiza (from Greek μύκης ', "fungus", and ῥίζα ', "root"; pl. mycorrhizae, mycorrhiza or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant ...

l association, in this case with the fungus '' Sebacina vermifera'' and is probably pollinated by a

thynnid The Thynnidae (also known as thynnid wasps or flower wasps) are a family (biology), family of large, solitary wasps whose larvae are almost universally parasitoids of various beetle larvae, especially those in the superfamily Scarabaeoidea. Until ...

wasp.

Conservation

''Caladenia actensis'' is listed as "critically endangered" (CR) under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). The main threats to the species include trampling by walkers, bicycles or horses, infrastructure building and maintenance, and weed invasion.

References

{{Taxonbar, from=Q9673273 actensis Plants described in 1999 Endemic orchids of Australia Orchids of the Australian Capital Territory Taxa named by David L. Jones (botanist) Taxa named by Mark Alwin Clements