Citrus glauca

Citrus glauca

The Desert lime or Australian-desert-lime, outback lime (Citrus glauca (Lindl.) Burkill, 1932) is a shrub or small tree species belonging to the Rutaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Plantae,
Magnoliophyta division,
Sapindales order,
Rutaceae family,
Genus Citrus,
Species C. glauca.
The terms are synonyms:
– Atalantia glauca (Lindl.) Benth. & Hook.f.,1862;
– Eremocitrus glauca (Lindl.) Swingle, 1914;
– Triphasia glauca Lindl., 1848.

Etymology –
The term Citrus comes from the Latin name of citron and lemon, from the Greek κέδρος kédros cedro and κίτρον kítron, lemon.
The specific glaucous epithet comes from the Greek γλαυκός glaucós glauco, greenish blue or blue-grey: due to the color of the bloom that covers the green parts of the plant.

Geographic Distribution and Habitat –
Citrus glauca is a plant native to Queensland, New South Wales and South Australia.
Its habitat is typical of the arid desert, steppe, where it grows together with low thorny shrubs of the Australian bush, where it forms formations of dry scrub and low woods.

Description –
Citrus glauca is usually a small thorny, evergreen shrub growing 2 to 3 meters in height or a small tree growing up to 10 meters in height.
The stems and branches are very thin and the green parts of the plant are covered by a glaucous, i.e. blue-green, waxy bloom.
The leaves are ribbon-like, elongated, erect or drooping.
The flowers are very small, with 4 white petals.
The fruits are round, yellow-green when ripe and have a diameter of 18-20 mm. The vacuoles of the peel are very rich in essences. The taste of the pulp is that of lemon (very acidic).

Cultivation –
Citrus glauca is certainly the citrus fruit with the greatest adaptability to extreme environments, tolerating poor soil, extreme drought, heat (45 °C), and cold -10 °C.
The fruit is harvested for local use and is becoming increasingly popular in the Australian bush food industry.
The species has some very interesting characteristics, linked to its environment of origin.
It has extreme resistance to heat, cold and drought. In particular due to the extremely arid climate it suffers the fall of the leaves, but the metabolism of the plant continues with the photosynthesis of the part of the bark of the young branches which is equipped with chlorophyll.
It has an extremely short life cycle between flowering (spring) and fruit ripening to make the best use of the short favorable periods, so fruiting takes place in less than three months from flowering, i.e. before the torrid heat. This is a very interesting feature among citrus fruits.
The production of bloom on the leaves (protective wax for the violent solar rays in the desert) is proportional to the violence of the solar irradiation; in conditions of normal solar irradiation the production of bloom is modest.
The plant is very thorny to protect itself from the nibbling of the leaves, but when the plant reaches a height, (if possible), such as not to be nibbled, the production of thorns ceases. Thus the costly production of spines is modulated.
The species has good variability, as regards the structure of the plant, the manner of flowering, fruiting, and size and type of fruit, to adapt to the various types of Australian environments. Various selections have been made in Australia that favor rational cultivation.
Furthermore, the species is easy to hybridize with lemon and bitter orange, and with intermediate hybrids, this is interesting for transferring its characteristics.
The plant is also used as a rootstock for Citrus species and has been crossed with other Citrus species to form more resistant hybrids.
From the pedological point of view it prefers a deep clayey soil, well drained but which retains humidity in full sun; moreover, the plants can tolerate saline soils and prefer a pH between 5 and 6.
The plants are very drought tolerant; in severe drought the leaves fall off and photosynthesis is carried out by the thin gray-green twigs.
Propagation occurs both by seed and by division of the root suckers.
Rooting of cuttings is listed as difficult. Sometimes the fruits are seedless or with aborted seeds, and the germination viability of the seeds is considered variable.
The initial growth of the seedlings is initially slow with poorly developed leaves, until an extensive root system has formed and humidity has been found; after which the growth becomes more vigorous and upwards and larger leaves are formed.

Customs and Traditions –
Citrus glauca, formerly classified as Eremocitrus glauca is a shrub whose fruits are increasingly valued by the Aboriginal people of Australia in bushfood and used in a variety of products, including jams, drinks and as a fruit glaze. It tastes quite similar to lime.
This plant is also harvested from the wild from bushy areas where it is relatively common.
Research indicates that C. glauca is one of the most heat, drought and cold tolerant species of the genus Citrus. Therefore it is potentially important for Citrus breeding programs; like the vast majority of members of the genus Citrus, it hybridizes easily with other species of the same genus.
The plant is still quite widespread in nature, and was used by the natives as an important resource but its spontaneous presence is decreasing due to the expansion of specialized agriculture. However, it is widely cultivated in its selected varieties, due to the higher productivity, uniformity of production and also for the possibility of mechanized harvesting.
Commercial cultivation is starting to reduce the exploitation of wild-collected produce.
Cultivation (drastically increasing) is practiced to obtain derivatives, drinks, juices and jams.
The fruit is a highly prized food.
No medicinal uses are known.
Among other uses, the agroforestry one is underlined and the plant, as mentioned, has been crossed with various citrus species to form more resistant hybrids.

Method of Preparation –
Citrus glauca is a plant whose fruits are eaten raw or cooked. The fruit can be eaten whole, in much the same way as a kumquat.
The acid fruit is used, complete with peel, to make refreshing drinks, jams, marmalades, sauces, etc.
The rind is soft, thin, and relatively free of bitterness for a citrus-like fruit, and the fruit contains a lot of acidic juice.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.

Photo source:
– https://inaturalist-open-data.s3.amazonaws.com/photos/29179733/original.jpeg

Attention: The pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not in any way represent a medical prescription; we therefore decline all responsibility for their use for curative, aesthetic or food purposes.