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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
Management
Similar Species
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Click on images to enlarge

infestation (Photo: Jason Weber)

habit of young plants (Photo: Simon Brooks)

habit in flower (Photo: Simon Brooks)

leaves (Photo: Jason Weber)

close-up of leaf blade (Photo: Jason Weber)

flowers and leaves (Photo: Jason Weber)

close-up of flower (Photo: Simon Brooks)

germinating seeds (Photo: Jason Weber)

seedlings (Photo: Jason Weber)

mature fruiting 'capsule' (Photo: Joe Vitelli and Barbara Madigan)

'capsule' segments and seeds (Photo: Joe Vitelli and Barbara Madigan)

Limnocharis flava

Scientific Name

Limnocharis flava (L.) Buch.

Synonyms

Alisma flava L.
Limnocharis emarginata Humb. & Bonp.

Family

Limnocharitaceae

Common Names

bur head, limnocharis, sawah flower rush, sawah lettuce, velvetleaf, yellow burr head, yellow burr-head, yellow burrhead, yellow sawah lettuce, yellow velvetleaf

Origin

This species is native to Mexico, the Caribbean (i.e. Cuba, the Dominican Republic, Grenada and Haiti), Central America (i.e. Costa Rica, Nicaragua and Panama) and tropical South America (Venezuela, Brazil, Bolivia, Colombia, Ecuador, Peru, northern Argentina and Paraguay).

Cultivation

Limnocharis (Limnocharis flava) has been cultivated as an ornamental aquatic plant in tropical regions.

Naturalised Distribution

Limnocharis (Limnocharis flava) was first found to be naturalised in Australia in 2001, when a population was detected in the Cairns area. Small infestations have since been located in other parts of northern Queensland (i.e. near Feluga, Mossman and Townsville).

It is also widely naturalised in south-eastern Asia (i.e. Cambodia, Vietnam, Brunei, Singapore, Thailand, Indonesia and Malaysia).

Habitat

A potential weed of wetter tropical environments. It inhabits freshwater bodies of water (i.e. dams, lakes and ponds), slow moving waterways, wetlands, swamps, marshes, irrigation channels, drainage ditches and ponded crops (e.g. rice).

Habit

A long-lived (i.e. perennial), clump-forming, aquatic herbaceous plant that is rooted to the ground and emerges above the water surface (i.e. it is emergent). It usually grows 20-120 cm tall.

Distinguishing Features

Stems and Leaves

The very large and somewhat fleshy leaves arise from the base of the plant, and are borne in clusters along a short thick upright (i.e. erect) stem (about 3cm long and 3 cm wide).

The leaves are hairless (i.e. glabrous) and contain a milky sap (i.e. latex). They are borne on long three-angled stalks (i.e. trigonous petioles) 5-90 cm long and have rounded (i.e. orbicular) leaf blades. The leaf blades (5-30 cm long and 4-25 cm wide) have blunt tips (i.e. obtuse apices) and entire or wavy (i.e. undulate) margins.

Flowers and Fruit

The flowers are borne in loose clusters (containing 2-15 flowers) at the top of long stalks (20-120 cm long). These upright flower stalks (i.e. erect peduncles) emerge from the base of the plant and are three-angled (i.e. trigonous), like the leaf stalks (i.e. petioles). About one to four of these flowering stalks are produced amongst each cluster of leaves. The individual flowers (2-4 cm across) are borne on short thick stalks (i.e. pedicels), 2-7 cm long, that emerge from the same point at the top of the flowering stems (i.e. they are arranged in an umbel). There are usually some small papery bracts present amongst the flower stalks (i.e. pedicels). Each flower has three large pale yellow petals (2-3 cm long and 1-2 cm wide), three overlapping green sepals (15-20 mm long and 10-15 mm wide), and a cluster of numerous bright yellow stamens at its centre. Flowering occurs throughout the year, depending on conditions (i.e. it usually flowers during wetter periods).

The upright flower stalks (i.e. peduncles) begin to droop as the fruit mature, and the persistent sepals become enlarged and enclose the developing fruit. The fruit are rounded 'capsules' (i.e. spherical follicles), 15-20 mm across, that split up into several (10-20) floating segments when mature. Each segment is semi-circular in shape and contains numerous ridged seeds (1-1.5 mm long) that are dark brown in colour and horseshoe-shaped.

Reproduction and Dispersal

This species reproduces by seed and vegetatively via creeping underground stems (i.e. rhizomes). Small plants (i.e. ramets) are sometimes also produced at the tops of the flowering stems.

The seeds and vegetative shoots are usually spread by water, but may also be dispersed in dumped garden and aquarium waste.

Environmental Impact

Yellow burrhead (Limnocharis flava) is regarded as a potentially significant environmental weed in Queensland, and has been targeted for eradication from this state. It was also recently listed as a priority environmental weed in at least one Natural Resource Management region and is included on the Nothern Australia Quarantine Strategy (NAQS) list.

Yellow burrhead (Limnocharis flava) is also very invasive in other parts of the world and in listed in the Global Invasive Species Database (GISD).

Legislation

Declared noxious in the following states and territories:

Management

For information on the management of this species see the following resources:

Similar Species

Yellow burrhead (Limnocharis flava) is similar to monochoria (Monochoria cyanea ), pickerel weed (Pontederia cordata) and water hyacinth (Eichhornia crassipes) when it is not in flower. It is also relatively similar to sagittaria (Sagittaria platyphylla). These species can be distinguished by the following differences: