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Ochna or mickey mouse plant (Ochna serrulata)

Ochna or mickey mouse plant (Ochna serrulata )

Click to enlarge Ochna serrulata fruit

Family: Ochnaceae

Status:

Description:
A dense evergreen shrub 2 to 4m high with stems which feel gritty to the touch due to the presence of numerous small protrusions. Leaves are glossy green on both surfaces, paler green below, with finely serrated edges, to 6cm long, in opposite pairs. Young growth is a bronze colour. Flowers are yellow with 5 petals. After the petals fall the calyx (the green cup in which the flower is seated) changes from green to red as the fruits mature. Fruits are succulent, about 8mm across, in clusters of 4-6. They ripen from green to black.

Preferred habitat and impacts:
Only found in the northern part of the area, from the Illawarra north. Found in dry and wet eucalypt forest and rainforest, where it can dominate the understorey and prevent regeneration by native plants.

Dispersal:
Birds, dumping of plants carrying seed.

Look-alikes:
The native shrub or small tree hairy clerodendrum (Clerodendrum tomentosum) has a similar fruit to ochna, with a berry ripening to black and seated on a fleshy red calyx. However, clerodendrum has only a single berry on each red calyx, instead of a cluster of 4-6 berries. The leaves of clerodendrum are quite different, being large (to 14cm long), and often velvety hairy, although old leaves may become hairless with time. It grows on rainforest edges north from Batemans Bay.
A native tree with similar leaves to ochna is the whalebone tree (Streblus brunonianus) which grows in rainforest north from Milton. It has leaves of similar size (to 7cm long by 1-4cm wide) to ochna, with finely serrated margins. They differ in being glossy on the upper surface, and they feel rough on both surfaces due to the presence of numerous small papillae (bumps) on the leaf surface. They are alternate on slightly zigzag stems, unlike ochna leaves which are opposite. Streblus stems do not feel rough, while ochna stems do.

Clerodendrum tomentosumStreblus brunonianus

Control:
Ochna is very resistant to herbicides, and re-sprouts vigorously if it is damaged. Seedlings may be dug out. Hand-pulling is likely to leave the taproot behind to re-grow, though small plants in moist soil can be pulled readily enough. Cut and paint or stem inject mature plants, preferably before they begin to develop seed. To improve the effectiveness when using the cut and paint method, peel the bark back all around the stump and apply herbicide quickly to both the cut face and the exposed outer wood. If using stem injection, use a knife to remove a strip of bark 10cm long and immediately apply herbicide to this area. Make 1-3 such strips around the trunk, depending on the plant size. Spray any regrowth. Selective herbicides will be most effective. Generally spraying works best on seedlings and regrowth with ochna, as the older dark green leaves do not absorb the herbicide well.