WEEDS

Rocky Hills, was for many decades, used for grazing cattle and probably sheep as well. Plant species surveys over many years have recorded about 160 species on Rocky Hill and about 55% of these are introduced species (‘weeds’). While that seems a reasonable number of native species, it should be remembered that there are about 10 tree/shrub species on Rocky Hill. Thus the majority of species are in the understorey. In the understorey the weeds totally dominate in terms of coverage and abundance. Most of the native understorey species are those species that were too small to be grazed or occurred in locations (e.g. between granite boulders) where they couldn’t be grazed.

Although subjective the two worst weeds of Rocky Hill are possibly fountain grass and Johnson grass.

Fountain grass (Cenchrus setaceus

Fountain grass is a tufted perennial grass to 1.5 m high. Leaves have a long narrow leaf blade to 3.5 mm wide and 60 cm long. The flower heads resemble pink to purple bottle brushes 6 to 30 cm long. Flowers are present from late spring to mid-winter.

It is a highly invasive tufted grass. Plants are used as ornamentals in gardens and along roadsides. Fountain grass seed is mainly wind-dispersed. Seed can remain viable in the soil for at least seven years. It is a fair chance that the plants on Rocky Hill established from wind-blown seeds that originated in Kooringal gardens. In 202? there was a major control program that killed the majority of fountain grass plants on Rocky Hill. Unfortunately the control team missed some areas and these plants are now flowering and setting seed.

Johnson grass (Sorghum halepense)

Johnson Grass is an erect perennial grass to 2 m high; the seed head is purplish-brown and pyramidal. Johnson is summer growing and goes brown in Wagga winters. It has rhizomes (underground stems) from which new shoots can arise. The rhizomes can be 10-20 cm deep which means it is very difficult to eradicate by mechanical means. It is also resistant to herbicides. It grows and spreads rapidly during wet summers. Wagga had several wet summers in the early 2020’s and Johnson grass is now probably the number one weed on Rocky Hill.

Other noticeable weeds of Rocky Hill are:

. wild oats

. fleabane

. St. John’s wort

. opium poppy

. African boxthorn

. twiggy mullein

Please note this website is still undergoing development. While we value your feedback at any time please be aware that changes continue even after the website was launched on World Environment Day, Wednesday 5th June 2024.

To download the full plant list, as at April 2024, click the button below: