Allocasuarina portuensis

Nielsen Park She-oak

Allocasuarina portuensis, commonly known as Nielsen Park she-oak, is a species of flowering plant in the family Casuarinaceae
It is endemic to a restricted part of the Sydney region in eastern New South Wales
It is a slender, dioecious shrub with branchlets up to 270 mm long
The leaves reduced to scales in whorls of seven or eight, the fruiting cones 12–15 mm long containing winged seeds (samaras) 4–5 mm long

Common name: Nielsen Park She-oak

Conservation status: Endangered

Allocasuarina portuensis is listed as "endangered" under the Australian Government Environment Protection and Biodiversity Conservation Act 1999 and the NSW Government Biodiversity Conservation Act 2016
Efforts to propagate and reintroduce the species began from the time it was identified, and plants were planted at several locations around Nielsen Park and nearby Gap Bluff and Hermit Point. 54 of these remained alive in 2000

Etymology:

Flowers

Male flowers are arranged in spikes resembling a string of beads 50–100 mm long, with about 3.5 to 4.5 whorls per cm, the anthers 0.8–1 mm long
Female cones are borne on a peduncle 2–15 mm long, the mature cones 12–15 mm long and 8–10 mm in diameter

Fruit:

Leaves:

The leaves reduced to erect or slightly overlapping, spreading to curved backwards, scale-like teeth 0.7–1.1 mm long, arranged in whorls of seven or eight around the branchlets

Stem & branches:

Its branchlets are spreading to drooping, up to 270 mm long
The sections of branchlet between the leaf whorls are 13–20 mm long and 0.8–1 mm wide, usually with a faint, waxy bloom

Roots:

Habit:

A slender, dioecious shrub that typically grows to a height of 3–5 m and has smooth bark

Habitat:

Distribution:

At the time of its discovery, only two male and six female plants were known, at six locations in the south-eastern part of Nielsen Park
It is likely that the species previously had a wider distribution, since the vegetation of Nielsen Park at the time of European settlement was widespread on the foreshore of Sydney Harbour, but has since been extensively cleared
At the time of its discovery, the species was growing in tall, closed woodland with Port Jackson fig (Ficus rubiginosa), smooth-barked apple (Angophora costata), blueberry ash (Elaeocarpus reticulatus) and cheese tree (Glochidion ferdinandi) in the canopy, and an understorey including Pittosporum revolutum, Kunzea ambigua and Monotoca elliptica
The original habitat was degraded by weeds, such as asparagus "fern" (Protasparagus densiflorus), wandering Jew (Tradescantia albiflora) and Lantana camara
The original vegetation may have been more sclerophyllous, the absence of recent wildfire allowing the presence of more mesophyllic species, such as Glochidion ferdinandi and Pittosporum revolutum

Additional notes:

Distinguishing similar species
- Nielsen Park she-oak resembles Allocasuarina rigida and A. diminuta, but both usually lack male flowers arranged like a string of beads
- Allocasuarina littoralis occurs in the same area as A. portuensis, but the former is a tree with fissured bark, also lacking the unusual arrangement of its male flowers.[6]
Taxonomy
- Allocasuarina portuensis was first formally described in 1989 by Lawrie Johnson in Flora of Australia from specimens collected in Sydney Harbour National Park in 198
- The species was discovered by Peter Brookhouse in the south-eastern part of Nielsen Park earlier the same year

Sources of information:

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