Bumble trees - our local native capers

Capparis species
Family: CAPPARACEAE
This is one of my favourite trees. It’s a venerable old bumble tree, Capparis mitchellii, out at Lake Broadwater (west of Dalby). The photo shows the break in the canopy, where perhaps another tree once grew. Capparis species often start life at the foot of another tree, appreciating the shelter, and behaving like climbers, using their thorns to climb up their neighbour.


Whatever the reason for it, this gap is now a favourite shady resting spot for kangaroos.

Here are some unripe fruits from the tree, which is the largest-fruited of the native capers. (Note also the butterfly eggs in this photo).





Overripe fruits turn orange, and smell like rotten oranges. They have earned the tree the common names of "Native Orange", "Wild Lemon", and "Native Pomegranate", although they are really like none of these things.
They are edible, when soft, but still green in colour.

Capers are one of our most valuable butterfly hosts. Five local species of caper butterflies breed on nothing else, and the plants can be spotted from afar because of the fluttering host which surrounds them. The commonest of these butterflies, known simply as the “caper white” (Belenois java - see photo at right) is a strongly migratory butterfly, often very conspicuous for its large numbers spread over hundreds of square kilometres, in early summer. The reasons for this migratory habit are not known, but may simply be the result of overpopulation in the area they are leaving. The other four species are very similar in appearance, and all are frequently seen together.
The caterpillars often infest their host plants to the extent of eating off every leaf and all the new shoots as well. The result would be not pretty, except for the beauty of the fluttering host surrounding the plant. The caper trees are used to it and bear it all stoically, bouncing back after every season with the renewed freshness of a plant that’s been skilfully pruned. One of the host plants, the caper relative called broombush (Apophyllum anomalum) saves time by being leafless in the first place.
The Caper White butterflies are a favourite food of Blue Wrens - another good reason for growing Bumble trees. The dense and sometimes prickly canopies of the tree capers are favourite nesting sites for a number of small birds.
We have five local caper species. Three of them are small trees ( and Capparis arborea, C. loranthifoliaC. mitchellii). Then there are their relatives, the prickly little bumble-bush (C. sarmentosa) and a scrambling shrub of the Darling Downs called “split jack” (C. lasiantha). They all have lovely white flowers, which, with their four petals, resemble butterflies themselves.


Fruit formation is a curious process. The dying flower puts out a fruit “stalk” from its centre, as though it’s holding its fruit away from it, at arm’s length.


















All the species are very prickly when young, with the characteristic paired spines situated where the leaf-stalks meet the stems. The juvenile leaves are very different from the adult ones, so it is difficult to identify this little plant (at right). It grows tucked up next to the trunk of a scrub wilga, in Franke Scrub near Highfields, where there three different Capparis possibilities.
They lose their prickles to a varying extent as they age. The little C. sarmentosa never loses them, and at the other end of the spectrum, the silvery-leaved tree from the eastern slopes of the Range, C. loranthifolia, can be completely prickle-free when it’s mature.
Capparis mitchellii is the best tree for the blacksoil, and other alkaline to neutral soils. Its range overlaps with C. arborea, on the edges of our redsoil. All the local native capers are very drought resistant, but C. mitchelli is the best for frost resistance.
The capers you buy in little bottles in the supermarket are the flower-buds, pickled, of Capparis spinosa, a shrub native to the Mediterranean region. There seems to be no reason why buds of our native species couldn’t be used for the same purpose. If you like capers - go for it! (But do plant your own trees if you want to do it in any quantity. Australia is long past the stage where wild harvesting of bush tucker can be considered ethically respectable.)