asthma plant

Chamaesyce hirta
Herb
Opposite
Simple
Green
Yellow
Cream
Green
Purple
Discoloured

A short-lived herbaceous plant producing a few spreading to almost upright stems usually growing up to 40 cm tall. Its reddish stems contain a milky sap and are covered in yellowish hairs. Its paired leaves (4-50 mm long) are borne on very short stalks and have lop-sided bases. These leaves are dark green or reddish with purplish markings and have paler undersides. Its 'flowers' are arranged into dense rounded clusters in the upper leaf forks. Its tiny hairy capsules (1-1.5 mm long) have three compartments, each containing a single light brown to reddish-brown seed.

Common names 
Also known as: asthma plant, asthma weed, asthmaplant, cat's hair, flowery headed spurge, garden spurge, hairy spurge, Jean Roberts, old blood, pill bearing spurge, pill-bearing spurge, pillpod sandmat, pillpod spurge, Queensland asthma weed, red euphorbia,
Family 
Euphorbiaceae
Deciduous 
No
Flowering time 
Spring - Summer
Native/Exotic 
Native
Origin 
This species is widely distributed throughout the topical regions of the world (i.e. pantropical), however it is generally thought to be an early introduction from the Americas into other tropical regions. It is thought to be native to southern USA, Mexic
Notifiable 
No
Council declaration 
SIL – Special Investigation List
Known distribution 

Widely naturalised in northern and eastern Australia, but most common and widespread in tropical and sub-tropical regions (i.e. in northern Western Australia, the Northern Territory, Queensland and north-eastern New South Wales).

Habitat 

A common weed of tended areas, such as lawns, gardens and footpaths.

Habit 

A short-lived (i.e. annual) herbaceous plant producing a few spreading to almost upright (i.e. decumbent to ascending) stems usually growing up to 40 cm tall, but occasionally reaching up to 60 cm in height.

Impact and control methods 

Asthma plant (Chamaesyce hirta) is a common weed of disturbed sites, waste areas, roadsides, gardens, footpaths, lawns, bare areas, crops and pastures in south-eastern Queensland. It sometimes also invades natural vegetation in the region, including forest margins, open woodlands, riparian vegetation and dry river beds.

Stem and leaves 

"The stems are thin, often reddish in colour, and moderately to densely-covered in yellowish hairs. The stems and leaves also contain a milky sap (i.e. latex).

The paired leaves are simple and borne on very short stalks (i.e. petioles) only 1-3.5 mm long. These leaves (4-50 mm long and 2-24 mm wide) are more or less egg-shaped in outline (i.e. ovate) or somewhat elongated (i.e. broadly-lanceolate) in shape. They have lop-sided (i.e. oblique) bases, finely toothed (i.e. serrulate) margins, and pointed or rounded tips (i.e. acute to obtuse apices). The leaves are dark green or reddish with purplish markings, which are more apparent when growing in sunny sites, and generally have paler greyish-green undersides. Both surfaces are initially covered in close-lying hairs (i.e. appressed pubescent), but the upper surfaces often become hairless with age (i.e. glabrescent)."

Flowers and fruits 

"Tiny male and female flowers are grouped into small cup-like structures (i.e. cyathia). Dense rounded clusters of these greenish, yellowish, creamy or reddish-coloured cyathia are produced in the upper leaf forks (i.e. axils) on stalks (i.e. peduncles) up to 25 mm long. Each cyathium consists of a small cup-like structure (i.e. involucre) 0.5-1 mm long with five minute teeth and four tiny red, pink or whitish petal-like appendages (i.e. glands) about 0.3 mm long. They also have four or five male flowers, each consisting of a single red stamen, and a single female flower, consisting of a large stalked ovary. Flowering occurs mainly during spring and summer.

The hairy capsules (1-1.5 mm long and 1-1.5 mm wide) have three compartments, each containing a single seed. The light brown to reddish-brown seeds (0.7-1 mm long and 0.4-0.5 mm wide) are four-sided or almost egg-shaped (i.e. ovoid-oblong) with wrinkled surfaces."

Reproduction and dispersal 

This species reproduces only by seed, which are dispersed by wind, water, vehicles, in soil and in contaminated agricultural produce.

Similar species 

"Asthma plant (Chamaesyce hirta) is very similar to Florida hammock sandmat (Chamaesyce ophthalmica ) and relatively similar to hyssopleaf sandmat (Chamaesyce hyssopifolia ). These species can be distinguished by the following differences:

■asthma plant (Chamaesyce hirta) has dark green or reddish coloured leaves and moderately to densely hairy stems. Its 'flowers' (i.e. cyathia) are borne in dense almost rounded clusters in the upper leaf forks (i.e. in axillary clusters).

■Florida hammock sandmat (Chamaesyce ophthalmica ) has light or dark green leaves and moderately to densely hairy stems. Its 'flowers' (i.e. cyathia) are borne in dense almost rounded clusters at the tips of the branches (i.e. in terminal clusters).

■hyssopleaf sandmat (Chamaesyce hyssopifolia ) has light or dark green leaves and hairless or sparsely hairy stems. Its 'flowers' (i.e. cyathia) are borne in relatively loose clusters in the upper leaf forks or at the tips of the branches (i.e. in axillary or terminal clusters)."