''Pterostylis excelsa'', commonly known as the tall rustyhood, or dry land green-hood is a flowering 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 ...

South Australia South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...

. It has a rosette of leaves and when flowering, up to twenty green or brown flowers which lean forward and have a thick, fleshy, partly hairy, insect-like labellum.

Description

''Pterostylis excelsa'', 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. It has a rosette of between five and twenty leaves long and wide. Flowering plants have a rosette at the base of the flowering spike but the leaves are usually withered by flowering time. Between two and twenty green, brown or green and brown flowers with translucent panels and long, wide are borne on a flowering spike tall. The flowers lean forward and there are between three and eight stem leaves wrapped around the flowering spike. The

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

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 ...

and

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 form a hood or "galea" over the column with the dorsal sepal having a narrow tip long. The

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

sepals turn downwards, are about the same width as the galea and suddenly taper to narrow tips long. The labellum is thick, fleshy, insect-like, long and about wide with short hairs on the "head" end and longer ones on the sides of the "body". Flowering occurs from August to December.

Taxonomy and naming

''Pterostylis excelsa'' was first formally described in 1986 by Mark Clements from a specimen grown in the

Australian National Botanic Gardens The Australian National Botanic Gardens (ANBG) is a heritage-listed botanical garden located in , Canberra, in the Australian Capital Territory, Australia. Established in 1949, the Gardens is administered by the Australian Government's Departme ...

from a tuber collected from the

Eyre Peninsula The Eyre Peninsula is a triangular peninsula in South Australia. It is bounded by the Spencer Gulf on the east, the Great Australian Bight on the west, and the Gawler Ranges to the north. Originally called Eyre’s Peninsula, it was named aft ...

. The description was published in the fourth edition of the ''Flora of South Australia''. 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 ...

(''excelsa'') is a

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 ...

word meaning "high", "lofty" or "distinguished". In 1941, William Nicholls described ''Pterostylis squamata'' var. ''valida'' and in 1994, David Jones raised it to species status as ''Pterostylis valida''. However, this name is regarded as a synonym of ''Pterostylis excelsa''.

Distribution and habitat

The tall rustyhood is widespread and locally common in the south-east of South Australia, sometimes growing in large colonies. It grows in scrubland and mallee, sometimes on rock outcrops in areas receiving an average annual rainfall of .

References

{{Taxonbar, from=Q15491537 excelsa Endemic orchids of Australia Orchids of South Australia Plants described in 1986