Chinee Apple is a declared weed in Qld, NT and WA and is such a pest locally that I had to laugh at the Wikipedia summary (above) which noted its “conservation status” as “least concern”.
The Brisbane City Council provides a good short overview of its growth habits:
A thorny and densely branched small tree. Its young stems have a zig-zagging nature and usually bear a single curved thorn at each joint. … Its rounded fruit (15-30 mm across) consist of a large hard stone surrounded by white fleshy pulp. These fruit turn from green to pale yellow, orange or reddish-brown as they mature. …
A weed of pastures, grasslands, open woodlands, floodplains, inland watercourses, roadsides, disturbed sites and waste areas in semi-arid, tropical and sub-tropical regions. …
Chinee apple (Ziziphus mauritiana) is widespread in the northern parts of Australia, but is most common in the northern and central regions of Queensland. It is also scattered throughout the northern parts of the Northern Territory and northern Western Australia, and has been recorded from south-eastern Queensland.
For more information, download the pdf from Queensland’s Department of Ag and Fish.
Wikipedia notes that, “In Queensland it is known as the Chinee/Chinkee apple as it was believed to be introduced by Chinese miners to areas such as Charters Towers, Ravenswood and Hughenden,” and that is what I have been told by people who grew up here, too. (Our species, incidentally, is Indian but has a temperate-climate Chinese relative.)
Why would they do such a thing? Well, in Asia it is cultivated for its fruit and they probably realised that it would grow well here, where temperate-climate plants struggle. The difference between “grows well” and “runs rampant” is sometimes small, and they probably didn’t realise just how well it would grow. (This is not a unique case, by any means. Prickly pear was introduced deliberately, and I’m not even going to mention escaped ornamental plants except to remind you of the “Grow Me Instead” programme.) Better introductions, like the mango, thrive with no maintenance but don’t take over.
Children growing up in Chinee apple areas in previous generations traditionally snacked on the fruit in season, as well as mangoes (of course), bush lemons (naturalised lemon trees, but that’s all I know) and tamarind. As a Victorian, I missed out, although I snacked in exactly the same way on roadside cherry-plums and apples in South Gippsland. I didn’t get around to sampling a Chinee apple until I picked a few on my way back from Mt Stuart a few days ago.
The fruit look for all the world like small plums and have a thin edible skin and a hard stone, again like plums. The reason for the common name ‘apple’ only becomes apparent when you bite into one: at the ideal ripeness, the texture is pleasantly crunchy, just like an apple. The flavour is neither strong nor distinctive, vaguely reminiscent of apple or peach. The fruit softens as it ripens further, passing through a pleasant-enough stone-fruit texture to an unattractive musky-smelling semi-liquid state.
Chinee apple as a resource
We are probably not getting the best fruit, of course. Wikipedia tells us that in India, “with sophisticated cultivation the fruit size may reach up to 6.25 cm long and 4.5 cm wide,” and, “there are 90 or more cultivars depending on the habit of the tree, leaf shape, fruit form, size, color, flavor, keeping quality, and fruiting season.” Wikipedia goes on to inform us that:
The major production regions for Indian jujube are the arid and semi arid regions of India. From 1984 to 1995 with improved cultivars the production was 0.9 million tonnes… The crop is also grown in Pakistan, Bangladesh and parts of Africa. Trees in northern India yield 80 to 200 kg of fresh fruit/tree/year when the trees are in their prime bearing age of 10–20 years.
Where the tree is cultivated, the fruit is eaten raw, stewed, dried, candied, pickled, or used in beverages. Furthermore, all parts of the plant are used – leaves for livestock feed, wood for furniture and house framing, thorny branches for temporary corrals, seeds and bark for medicinal purposes, flowers as a nectar source for honey bees. And finally:
The fatty-acid methyl ester of Z. mauritiana seed oil meets all of the major biodiesel requirements in the USA (ASTM D 6751-02, ASTM PS 121-99), Germany (DIN V 51606) and European Union (EN 14214). The average oil yield is 4.95 kg oil/tree or 1371 kg oil/hectare, and arid or semi-arid regions may be utilised due to its drought resistance.
We’re missing a fantastic opportunity here!