Weeds of Australia - Fact Sheet

Top Scientific Name Synonyms Family Common Names Origin Cultivation Naturalised Distribution Habitat Habit Distinguishing Features Stems and Leaves Flowers and Fruit Reproduction and Dispersal Environmental Impact Legislation Similar Species

Scientific Name

Crataegus x sinaica Boiss.

Synonyms

Crataegus sinaica Boiss.
Crataegus monogyna Jacq. x Crataegus azarolus L.

Family

Malaceae (New South Wales)
Rosaceae (Queensland, the ACT, Victoria, Tasmania, South Australia and Western Australia)

Common Names

azarola thorn, azzarola, azzarola hawthorn, azzarola thorn, hawthorn, may, Mount Sinai thorn, Neapolitan medlar, whitethorn

Origin

This natural hybrid (sometimes now considered a species) is native to the Middle East. It is thought to be a hybrid of hawthorn (Crataegus monogyna) and azarole (Crataegus azarolus).

Cultivation

This hybrid is grown as a garden ornamental in the temperate regions of Australia.

Naturalised Distribution

Azzarola (Crataegus x sinaica) is not yet widely naturalised in Australia. It is naturalised near populated areas in some parts of south-eastern Australia (i.e. near Adelaide in south-eastern South Australia and Melbourne in southern Victoria).

Habitat

A weed of coastal and sub-coastal temperate regions. It infests old gardens, disturbed sites, waste areas and degraded native habitats near populated areas.

Habit

An upright (i.e. erect) shrub or small tree usually growing from 2-6 m tall, but occasionally reaching up to 10 m in height. It loses its leaves during winter (i.e. it is deciduous).

Distinguishing Features

• an upright shrub or small tree (usually growing from 2-6 m tall) that loses its leaves during winter.
  
  
• its stems are armed with a few stout thorns (5-25 mm long).
  
  
• its wedge-shaped leaves have variously lobed or toothed margins.
  
  
• its flowers are either white, cream or pink (about 15 mm across) and are borne in clusters along the branches.
  
  
• its shiny, rounded, red 'berries' (10-25 mm across) are yellow on the inside and contain two or three hard 'seeds' (5-7 mm across).

Stems and Leaves

The stems are much-branched and armed with a few stout thorns (5-25 mm long). Younger stems are greenish and covered in soft hairs (i.e. they are pubescent), but they turn brown or grey in colour and become hairless (i.e. glabrous) as they mature. The bark becomes somewhat roughened towards the base of older plants.

The alternately arranged leaves (1-6 cm long and 1-6 cm wide) are borne on long stalks (i.e. petioles). These leaves are wedge-shaped (i.e. cuneate) and mostly hairless (i.e. glabrous). They are deeply lobed, with 3-5 lobes, and may also be coarsely toothed (i.e. serrated), particularly towards their tips (i.e. apices).

Flowers and Fruit

The flowers are either white, cream or pinkish in colour (about 15 mm across) and have five petals. They also have five small sepals, numerous stamens and two styles. These flowers are borne on short, hairy, stalks (i.e. pubescent pedicels) and are grouped into small clusters along the branches. Flowering occurs mostly during spring and sometimes into early summer (i.e. mainly in October).

The fruit is a large, shiny, rounded, 'berry' (i.e. pome) that is yellow on the inside. These fruit (10-25 mm across) turn from green to orange-red or red in colour as they mature. They contain two or three brown, egg-shaped (i.e. ovoid), 'seeds' (i.e. nutlets or pyrenes) that are hard and stony in nature and 5-7 mm across.

Reproduction and Dispersal

This species reproduces by seed, which are most commonly spread by birds that eat the brightly coloured fruit. The fruit may also be spread by other animals, water, or in dumped garden waste.

Environmental Impact

This species is regarded as a significant environmental weed in South Australia, particularly in the Greater Adelaide Region. It invades hillsides and waterways in the Northern and Southern Mount Lofty Mountains, and is present in conservation areas within this region (e.g. Brownhill Creek Recreation Park and Little Mount Crawford Native Forest Reserve).

Legislation

This species is declared under legislation in the following states and territories:

• South Australia: 5* - this species is declared under Class 5a and control is only required in part of the state. See the Consolidated Proclaimed Plants List, produced by Primary Industries and Resources, South Australia, for more information about legislation for specific areas.
  
  
• Western Australia: Prohibited - on the prohibited species list and not permitted entry into the state.

Similar Species

Azzarola (Crataegus x sinaica) is very similar to azarole (Crataegus azarolus), hawthorn (Crataegus monogyna) and smooth hawthorn (Crataegus laevigata). These species can be distinguished by the following differences:

• azzarola (Crataegus x sinaica) has relatively large fruit (10-25 mm across) that contain two or three hard 'seeds' (i.e. pyrenes). Its young stems are covered in soft hairs (i.e. they are pubescent).
  
  
• azarole (Crataegus azarolus) is a spineless plant with relatively large, yellow-orange, fruit (up to 20 mm across) that usually contain two or three hard 'seeds' (i.e. pyrenes). Its young stems are covered in soft hairs (i.e. they are pubescent).
  
  
• hawthorn (Crataegus monogyna) has relatively small fruit (5-12 mm across) that contain a single hard 'seed' (i.e. pyrene). Its young stems are generally hairless (i.e. glabrous), smooth and reddish-brown in colour.
  
  
• smooth hawthorn (Crataegus laevigata) has relatively small fruit (up to 15 mm long) that contain two hard 'seeds' (i.e. pyrenes). Its young stems are generally hairless (i.e. glabrous) and smooth.

Azzarola (Crataegus x sinaica) is also relatively similar to the cotoneasters (Cotoneaster spp.), the firethorns (Pyracantha spp.) and Indian hawthorn (Rhaphiolepis indica). However, all of these species have leaves with entire or finely toothed margins, and the cotoneasters (Cotoneaster spp.) and Indian hawthorn (Rhaphiolepis indica) do not have any thorns on their stems.