Broad-leaved Drumsticks

Appearance

"Isopogon anemonifolius" grows as an evergreen, woody shrub to 1–1.5 m in height, but is restricted to approximately 50 cm on exposed heaths and headlands. The leaves are 5–11 cm long and forked after 2–5 cm into three segments, then often forked a second time. The leaf tips are pointed. Leaves can vary markedly on single plants, with some leaves undivided. Leaf surfaces are generally smooth, though occasionally covered with fine hair. Its flat leaves distinguish it from the terete leaves of "Isopogon anethifolius"; they are also broader, at 3–5 mm wide compared with the 1 mm wide leaves of the latter species. The new growth and leaves of "I. anemonifolius" may be flushed red to purple, particularly in winter. The globular inflorescences appear any time from July to January, being most abundant in October. They are 3–4 cm in diameter, and grow terminally at the tips of branches, or occasionally axillary. The individual flowers average 1.2 cm long. They are straight stalkless structures arising from a basal scale. The perianth, a tube that envelopes the flower's sexual organs, splits into four segments, revealing a thin delicate style tipped with the stigma. At the ends of the four perianth segments are the male pollen-bearing structures known as anthers. Arranged in a spiral pattern, the flowers open from the bottom of the flowerhead inwards. Flowering is followed by the development of the round fruiting cones, which have a diameter of 1–1.6 cm. The seed-bearing nuts are small—less than 4 mm across—and lined with hairs.

Distribution

"I. anemonifolius" is found along the east coast of New South Wales, from near the Victorian border almost to Queensland. It is most common between Smoky Cape and Ulladulla. There is an outlying population in the vicinity of Torrington in the New England region. It occurs naturally from sea level to 1200 m and is found on low-nutrient sandstone soils in heathland and dry sclerophyll woodland, particularly along ridges or tops of hills. Typical woodland trees it is associated with include the scribbly gums "Eucalyptus haemastoma" and "E. sclerophylla", yertchuk, yellow bloodwood, red bloodwood and smooth-barked apple, and heathland plants such as rusty banksia, swamp banksia, mountain devil, conesticks, tick bush, forest oak and "Hakea laevipes".

Habitat

"I. anemonifolius" is found along the east coast of New South Wales, from near the Victorian border almost to Queensland. It is most common between Smoky Cape and Ulladulla. There is an outlying population in the vicinity of Torrington in the New England region. It occurs naturally from sea level to 1200 m and is found on low-nutrient sandstone soils in heathland and dry sclerophyll woodland, particularly along ridges or tops of hills. Typical woodland trees it is associated with include the scribbly gums "Eucalyptus haemastoma" and "E. sclerophylla", yertchuk, yellow bloodwood, red bloodwood and smooth-barked apple, and heathland plants such as rusty banksia, swamp banksia, mountain devil, conesticks, tick bush, forest oak and "Hakea laevipes"."I. anemonifolius" is a long-lived plant, with a lifespan of 60 years. It resprouts from its woody base, known as a lignotuber, approximately two months after being burnt in a bushfire. The resultant new growth takes two years to flower, though older plants with larger lignotubers are able to re-grow more quickly. "I. anemonifolius" is slow-growing; a 1990 field study in Brisbane Water National Park found that the lignotuber grew at a rate of 0.173 cm per existing cm of lignotuber per year, yielding a lignotuber of around 1 cm in diameter at 10 years of age and 5 cm diameter at 20 years of age. The largest lignotubers found have a diameter of 40 cm.

Plants need a lignotuber of 2 cm diameter to survive low intensity fires. Plants are able to resprout after more intense fires once they reach 15 years of age. "I. anemonifolius" is also serotinous—the seeds are held on the plant as a canopy-based seedbank and are released after fire. Most seedlings arise within a year of a bushfire, though very few are seen at other times. The seedbank is most productive between 25 and 35 years after a previous fire. However, seedlings may be outcompeted by seedlings of obligate seeder species. The seeds of "I. anemonifolius" fall directly to the ground or are blown a short distance by wind. Young plants flower about seven years after germinating from seed. Repeated bushfire intervals of less than 10 years' duration are likely to result both in reduced survival of older plants and in recruitment of seedlings, possibly leading to local extinction in 50 years. Intervals of at least 12–13 years for low intensity fires and 15 years for hotter fires are needed for population stability.

Leaf spotting is caused by the fungus "Vizella". Flower buds may be damaged by weevils.