Botanical name

Acacia synchronicia (broad phyllode variant)

Description

Somewhat straggly, openly branched, glabrous shrubs or small trees 2-4 m tall, main stems somewhat crooked. Bark grey and finely longitudinally fissured except upper branches are smooth and lightly pruinose. Branchlets pruinose. New shoots pale green, thin-textured. Stipules spiny, slender, 3-6 mm long, present on young plants but often absent from mature plants. Phyllodes elliptic to ovate-elliptic, 15-20 (-25) mm long, 8-11 mm wide, l:w = 1.5-2.5, rather thick and fleshy when fresh, very finely wrinkled when dry, glaucous to sub-glaucous (rare green phyllode individuals occur in some populations), pruinose ; midrib obscure or not evident when dry; apex obtuse. Gland quite prominent, situated on upper margin of phyllode 0-0.5 mm above the pulvinus, 0.7-1 mm long. Inflorescences simple (not racemose), initiated on new shoots as in the typical variant of A. synchronicia; peduncles slender, 15-20 mm long; heads (few seen) globular, golden, 50-60-flowered. Flowers 5 merous; sepals free, linear-spathulate. Pods and seeds not seen.

Characteristic features

Somewhat straggly, openly branched, shrubs or small trees, upper branches lightly pruinose. Branchlets pruinose. Stipules spiny, present on young plants but usually absent from mature plants. Phyllodes elliptic to ovate-elliptic, short and broad (mostly 15-20 x 8-11 mm with l:w = 1.5-2.5), rather thick and fleshy when fresh, very finely wrinkled when dry, glaucous to sub-glaucous (rarely green), pruinose, midrib obscure or not evident when dry, apices obtuse ; basal gland quite prominent. Inflorescences simple, initiated on new shoots as in the typical variant of A. synchronicia; heads globular, golden.

Distribution and ecology

Occurs in the Pilbara region of northwest Western Australia where it is scattered from near Marble south to Ethel Creek Station (northeast of Newman). Broad phyllode specimens of A. synchronicia also occur outside the Pilbara, however, it is not known if these represent the same biological entity that is described here (which is based only on Pilbara plants). The Pilbara plants are found along diffuse drainage lines (where they may be locally common) in low rocky hills or on stony spinifex plains in red-brown clay-loam.

Flowering and fruiting period

Few specimens have been seen of this taxon, however, as best as can be judged from the material to hand it seems that flowering would commence in September or later, similar to that of the typical variant of A. synchronicia. Pods have not been seen.

Taxonomy

Further study is needed to assess the status of this taxon. It is clearly closely related to A. synchronicia (with which it sometimes grows) and current evidence suggests that it is simply a broad phyllode variant of that species. It appears that it is mainly phyllode dimensions that separate the two taxa, 15-25 (-35) mm long and 3-7 mm wide with l:w = 3-7 in typical A. synchronicia and 15-20 (-25) mm long and 8-11 mm wide with l:w = 1.5-2.5 in the broad phyllode variant. There are a few specimens that are seemingly intermediate for these attributes and cannot be placed in either variant with confidence. Plants of the broad phyllode variant are often more conspicuously pruinose than those of the typical variant. In phyllode shape and size and branchlet pruinosity the broad phyllode variant of A. synchronicia is superficially very similar to A. glaucocaesia which is distinguished by its predominantly racemose inflorescences of paler yellow heads and more thinly textured phyllodes with a smaller basal gland.

Conservation status

Not considered rare or endangered.