24 November 2013

Trymalium myrtillus subsp. myrtillus – Rhamnaceae

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Trymalium myrtillus subsp. myrtillus – Rhamnaceae

Many plants in the Rhamnaceae family of which Trymalium belongs can be quite tricky to identify, as can the similar looking genera. Trymalium is most similar to Spryridium and Pomaderris, but can be separated by the flower arrangement of Spryridium that are in heads (small basket like), whereas Pomaderris and Trymalium are not. These two are distinguished by their petals of which Trymalium are shaped like a tiny hood that initially cover individual anthers, but the petals of Pomaderris are not hooded and typically petal shaped.

There are two subspecies of Trymalium myrtillus with subsp. myrtillus being the only one in the Esperance region, whilst the other (subsp. pungens) is a rare spiny shrub to the north of Bremer Bay (250 km or 155 miles WSW of Esperance). Trymalium myrtillus subsp. myrtillus is common from Bremer Bay to the edge of the Nullarbor and north to the Kalgoorlie region.

Trymalium myrtillus subsp. myrtillus although common is habitat specific favouring areas on and around granite outcrops, especially where the brown soils of these locations also overlie limestone. The cream/yellow flowers are arranged in panicles (branched raceme like) and although small (to 2 mm or less than 1/8” diameter), occur in such quantities as to overwhelm the green foliage.

Plants can grow to 3 metres (10’) in height, but locally tend to be around half that size and probably due to their favoured habitat often grow in close-knit colonies, so once stumbled upon are not easily overlooked. It is recorded flowering from July to October, which may vary slightly depending on local weather conditions.