Stackhousia monogyna - Creamy Candles

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Stackhousia monogyna - Creamy Candles

Plants belonging to the Stackhousia genus are herbs or sub-shrubs and part of the Celastraceae family, although they may still be listed under Stackhousiaceae by some authorities. Stackhousia monogyna is a highly variable and widely distributed species, being found in WA, SA, Victoria, Tasmania, NSW and Qld. With such a wide distribution variations are to be expected, but with this plant, this trait is exhibited even within the Esperance region.

Growing to 60 cm (2’) in height, it can be spreading or rigidly upright; the flower spikes can be pure white to creamy yellow and the individual flowers tightly packed or openly spaced around the stem, or on one side. Foliage can be deep green to pale blue, be hairy or glabrous and arranged either near the base or along the stems, plus sparsely spaced or densely packed together. So it is not surprising that thoughts of finding another Stackhousia species are not uncommon, but currently Stackhousia monogyna is the only species in the Esperance region with creamy white flowers, although at some stage this complex is likely to be reviewed.

Stackhousia monogyna is not very particular about soil type, providing it remains moist, but not waterlogged around its flowering time. However inland, it is more commonly found around granite outcrops where water run-off provides additional moisture. In dry zones (often sandy soils) during summer this species behaves as an annual, but if less severe, as a perennial, although the stem and leaves may die back to re-shoot from the roots, or stem base the following year.

Plants in this genus can usually be found in scattered small colonies, but after bushfires or soil disturbance, can regenerate to temporally dominate the habitat, but within a few seasons will be pushed out by longer living species. They produce flowers over several weeks and are recorded in bloom from June to December, but this would depend on habitat type and local rainfall, although locally between August to October is usually when they are at their best.

Stackhousia scoparia – Broom Stackhousia

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Stackhousia scoparia – Broom Stackhousia

This species is easily overlooked as it is short and broom-like (leaves reduced to scales) and has dark brown flowers. It was originally placed in the Stackhousiaceae family, but has now been absorbed (with the rest of the old family) into Celastraceae. When I first encountered Stackhousia scoparia, I thought it was a Tripterococcus (also from the Celastraceae family), but fortunately it had seed capsules that are a different shape to that genus (see Tripterococcus brunonis in lower right column), which are strongly winged.

Stackhousia scoparia grows to 60 cm (2’) in height, but is mostly shorter and can be locally common after bushfire when plant competition has been removed. In the Esperance district it has a preference for sandy hollows where the soil has a higher clay content than higher surrounding ground, although it is recorded growing on gravel and laterite elsewhere. This species is predominantly an inland one and occurs in mallee country to the North and NE of Esperance, and at these and higher latitudes, ranges west to the Perth region.

The tubular brown flowers (also green/yellow to yellow/brown) are around 5 mm (under ¼”) in length, but are not unattractive when closely examined and would require something like a butterfly or moth with a long proboscis to pollinate them. Unlike its larger flowered and very common relative Stackhousia monogyna with its radiating candle-like flower spikes, the flowers of Stackhousia scoparia are grouped along one side of the stem.

The distinctive seed capsules (cocci) are rounded, but deeply wrinkled or covered in tubercles (as illustrated) and as proof, will produce additional flowers in the advent of later storms over the irregular mallee rainfall region. Therefore depending on weather conditions, Stackhousia scoparia can flower anytime from August to January.