''Angophora leiocarpa'', commonly known as rusty gum, is a species of small to medium-sized tree that 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 els ...

to eastern Australia. It has smooth bark on the trunk and branches, lance-shaped adult leaves, flower buds usually in groups of three, white or creamy white flowers and smooth barrel-shaped to cup-shaped fruit.

Description

''Angophora leiocarpa'' is a tree that typically grows to a height of and forms a

lignotuber A lignotuber is a woody swelling of the root crown possessed by some plants as a protection against destruction of the plant stem, such as by fire. Other woody plants may develop basal burls as a similar survival strategy, often as a response t ...

. It has smooth pink to orange or greyish bark that is shed in small patches. Young plants and

coppice Coppicing is a traditional method of woodland management which exploits the capacity of many species of trees to put out new shoots from their stump or roots if cut down. In a coppiced wood, which is called a copse, young tree stems are repea ...

regrowth have

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

leaves that are narrow lance-shaped, long and wide with a stem-clasping base, and arranged in opposite pairs. Adult leaves are also arranged in opposite pairs, lance-shaped or curved, long and wide tapering to a petiole long. The flower buds are arranged on the ends of branchlets on a branched,

glabrous Glabrousness (from the Latin '' glaber'' meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack of hair, down, setae, trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part o ...

peduncle Peduncle may refer to: *Peduncle (botany), a stalk supporting an inflorescence, which is the part of the shoot of seed plants where flowers are formed *Peduncle (anatomy), a stem, through which a mass of tissue is attached to a body **Peduncle (art ...

long, each branch of the peduncle with three, rarely seven buds, on

pedicels In botany, a pedicel is a stem that attaches a single flower to the inflorescence. Such inflorescences are described as ''pedicellate''. Description Pedicel refers to a structure connecting a single flower to its inflorescence. In the absenc ...

long. Mature buds are globe-shaped, long and wide with a smooth to slightly ribbed floral cup and

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

s about long and wide. Flowering has been observed from November to February and the fruit is a thin-walled, barrel-shaped to cup-shaped capsule long and wide with the valves enclosed in the fruit.

Taxonomy and naming

Rusty gum was first formally described in 1986 by

Gregory John Leach Gregory may refer to: People and fictional characters * Gregory (given name), including a list of people and fictional characters with the given name * Gregory (surname), a surname Places Australia *Gregory, Queensland, a town in the Shire o ...

from an unpublished description by Lawrie Johnson and given the name ''Angophora costata'' subsp. ''leiocarpa'' from specimens collected near Warialda High School in 1976. In 1988

Kevin Thiele Kevin R. Thiele is currently an adjunct associate professor at the University of Western Australia and the director of Taxonomy Australia. He was the curator of the Western Australian Herbarium from 2006 to 2015. His research interests include ...

and

Pauline Ladiges Pauline Yvonne Ladiges (born 1948) is a botanist Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this fi ...

raised it to species status as ''Angophora leiocarpa''. 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 ...

(''leiocarpa'') is derived from the

ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic p ...

''leios'' meaning "smooth" and ''karpon'' meaning "fruit", distinguishing this ''Angophora'' from others in the genus. A 2021 molecular analysis of the genus confirmed it was genetically divergent from the two ''A. costata'' subspecies, and in fact showed some hybridization with ''

Angophora floribunda ''Angophora floribunda'', commonly known as the rough-barked apple, is a common woodland and forest tree of the family Myrtaceae native to Eastern Australia. Reaching 30 m (100 ft) high, it is a large tree with fibrous bark and cream-wh ...

''.

Distribution and habitat

''Angophora leiocarpa'' grows in open forest on sandstone hills and outcrops from

Blackall Blackall is a rural town and locality in the Blackall-Tambo Region, Queensland, Australia. In the the locality of Blackall had a population of 1,416 people. The town is the service centre for the Blackall-Tambo Region. The dominant industry ...

and

Mackay Mackay may refer to: *Clan Mackay, the Scottish clan from which the surname "MacKay" derives Mackay may also refer to: Places Australia * Mackay Region, a local government area ** Mackay, Queensland, a city in the above region *** Mackay Airport ...

in Queensland, south to

Narrabri Narrabri ( ) is a locality and seat of Narrabri Shire local government area in the North West Slopes, New South Wales, Australia on the Namoi River, northwest of Sydney. It sits on the junction of the Kamilaroi Highway and the Newell Highwa ...

and

Grafton Grafton may refer to: Places Australia * Grafton, New South Wales Canada * Grafton, New Brunswick * Grafton, Nova Scotia * Grafton, Ontario England * Grafton, Cheshire * Grafton, Herefordshire *Grafton, North Yorkshire * Grafton, Oxfordshi ...

in New South Wales.

References

{{Taxonbar, from=Q3953135 leiocarpa Flora of New South Wales Flora of Queensland Trees of Australia Ornamental trees Taxa named by Kevin Thiele Plants described in 1986