Common Name(s): Western Myall

Synonym(s):

Family: Fabaceae

Native To: Australia

Native Habitat: Found in a range of soils from sandy loam to clay, in high pH sites, in open woodland or shrubland.

Growth Habit: Multi-stemmed shrub/small tree that can grow to over 20 feet tall, with spreading flexible branches that are often pendulous.

Flowering: February into March

Distinguishing Characteristics: Bark is rough and fissured. Phyllodes (modified leaves) resemble needles, from 1.5 - 4.5 inches long. They are flat, and end in softly curved innocuous tips. The phyllodes are spaced ½ inch apart, giving each branch a “loose” appearance. Flowers are small yellow puffs, 2 to 5 clustered together in the leaf axils. Fruits are legumes, 3-4 inches long, papery, with a width of about 1/4 inch. They are flat, and are slightly raised and constricted between the seeds. The seeds are small, black, and very hard.

Natural History and Cultivation Notes: An interesting question is what prevents Western Myall seedling establishment in its native range. Seeds fail to germinate in most years. A paper (Ireland, 1992) addressing the lack of seedling emergence noted that ants (various species) normally carry seeds off and destroy them. (This seems to have happened on the UA campus). A combination of events must occur for seedlings to establish: high late-summer rains, combined with sheeting water flows which scarify the seeds - and presumably flush out ants, shallow burying of seeds, follow up rains that encourage seedlings, and low herbivore populations. Sounds right. In Western Australia, these events only occur together, on average, every 20 years. Growers should try to mimic these conditions, of course.

The UA’s Acacia papyrocarpa was plated on campus during the Warren Jones era of “interesting tree experiments” in the 1980s. In the 20 years or more on the site, it has stretched, flopped, draped and spread to about 16 feet wide. On the west side of Yavapai Hall, it gets full afternoon sun and reflected heat until about 4 pm in summer. This site has been a good one; the tree has rarely suffered through a killer summer, and more importantly, seems to be hardy down to the mid teens.

Ethnobotany: The wood of Acacia papyrocarpa was used by the Aborigines, and may still be, for musical instruments and tools. In landscaping, Western Myall is a blue cloud that would certainly catch one’s eye. It is only moderately messy, since the leaves/phyllodes hang on for many seasons. This is one of those plants that probably would never look better with pruning. It could be used as a focal point, but would need room to spread. But more importantly, this thornless tree is tough as nails, and withstands all the our increasingly hot summers with nary a whimper.

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