Eremocitrus Glauca

This is a remarkable plant that grows in arid, near desert conditions, and can survive some frost.
However, it is often said to be hardy to -24C.
This is incorrect and arose from an error in the first edition of The Citrus Industry, Vol. 1.
This described hardiness to......................"ten or more degrees below zero Fahrenheit (-5.5C or lower)".
What was meant was..............................."ten or more degrees below freezing Fahrenheit (-5.5C or lower)".
The second edition now corrected the wrong part of this mistake,
claiming hardiness to..............................."ten or more degrees below zero Fahrenheit (-24C or lower)."
Evidence from USA confirms plants do not survive freezes of around -10C.

Desert lime (or lime bush) is a true citrus, with blue-grey leaves and prickles along the branches. It is usually found growing on clay or heavy clay soils, often as clumps of short bushes (2 - 3m in height). They are occasionally found as single large trees to 5-6m in height. Older trees have a weeping appearance and have few, or no, prickles. Limes are common in the southern and western Darling Downs, especially in Brigalow, or cleared Brigalow, country. Limes also grow further west, eg in the Longreach, Blackall and Tambo districts where they are often found along creek lines and on slightly scalded country. The fruit can be picked when still green, and has a pleasantly refreshing and tangy taste. Desert lime fruit is extremely popular and becoming very well known within the bush food industry. The fruit is used in a variety of sauces and jams. Fruit is also used within restaurants. The plant has even been investigated overseas as a potential source of drought hardy rootstock for citrus trees.

I am growing two types of seedlings of Eremocitrus glauca. Seeds were sent direct from Australia in 1997, but over the years most have died. In 1996 I was given seeds from USA. Only one germinated and survived, producing a somewhat different plant. This leads me to suspect that the USA seedling is probably a hybrid. Reference books say that Eremocitrus does hybridise easily when grown near other citrus.
I also now have one small plant budded from a mature tree. This is thornless and has distinctive matt grey leaves with nearly identical upper and lower surfaces. This is typical of the species' mature leaf form.

The USA seedling has grown extremely rapidly, producing a tangled multi-branched shrub about 1.5m high in 5 years. I have recently managed to bud this on to a citrange seedling where it is also thriving. A notable feature of this plant is that the spines often develop a 'knee' which then produce a new shoot.

The pictures here show an example of Citrus glauca growing in the "Parque de los Principes" in Sevilla, Andalucia in southern Spain.
The first two photographs were taken in 1993 by José Manuel Sánchez de Lorenzo Cáceres, and reproduced here with permission. The second pair were taken in 2003 by a friend of mine on holiday. He was of the opinion that the tree is not in a healthy condition. The foliage certainly now appears less dense and more branches can be seen through it. Compare these pictures with the one I took in Riverside, California.

Left is the best Australian seedling, now about 2' (60cms) tall. The budded plant is shown below.

The spindly nature of the growth on these plants makes low resolution display poor. Please click on the photos for higher definition images.