giant sensitive plant

Mimosa diplotricha var. diplotricha
Shrub
Alternate
Compound
Pink
Green

Mimosa diplotricha grows as an erect shrub or a scrambling climber, reaching a height of around 3 m. Its leaves are bipinnate and bright green with a feathery appearance. They are arranged alternately along the stems. Each leaf contains around twenty pairs of small sessile lanceolate leaflets arranged opposite each other. Each leaflet measures around 6 to 12 mm long and 1.5 mm wide. Like the related Mimosa pudica, the leaves are sensitive to touch, and will curl up if disturbed.

Common names 
Also known as: creeping sensitive plant, giant sensitive plant, nila grass, tropical blackberry,
Family 
Fabaceae
Deciduous 
No
Flowering time 
Autumn- Winter
Native/Exotic 
Native
Origin 
Mexico, Central America and tropical South America
Notifiable 
No
State declaration 
Category 3 - Must not be distributed or disposed. This means it must not be released into the environment unless the distribution or disposal is authorised in a regulation or under a permit.
Council declaration 
As per State Declaration
Known distribution 

Giant sensitive weed (Mimosa diplotricha var. diplotricha) is currently mostly confined to the coastal regions of northern Queensland, but is also present in central Queensland and on Christmas Island.

Habitat 

This species is mainly found in wetter habitats in tropical and sub-tropical regions. It is usually a weed of roadsides, waste areas, disturbed sites, waterways, pastures and plantation crops (e.g. sugarcane).

Habit 

This species may exhibit several different growth forms and can develop into very dense thickets. It varies from being a relatively short-lived (i.e. annual, biennial or perennial) shrub with upright (i.e. erect or ascending) stems (2-3 m tall) to a climbing plant with creeping (i.e. prostrate) or scrambling stems (occasionally reaching up to 6 m long)

Impact and control methods 

Mimosa diplotricha is fast-growing and can tolerate a wide range of soil and climate conditions. It has the ability to climb over and smother other plants and can shade out light-demanding species, preventing the natural regeneration of other plants, and it constitutes a wildland fire hazard when dry Left alone, they can form impenetrable thickets within a short period that can affect movement of both people and animals, as well as planted crops. All parts of the plant are toxic to grazing animals

Stem and leaves 

The stems become somewhat woody with age and are much-branched from the base of the plant. They are strongly four or five-angled and armed with numerous small backwards-curved (i.e. recurved) prickles (3-6 mm long).
The bright green leaves (10-20 cm long) are twice-compound (i.e. bipinnate) and alternately arranged along the stems. They are borne on prickly stalks (i.e. petioles) and consist of 4-9 pairs of branchlets (i.e. pinnae). Each branchlet (i.e. pinna) bears 12-30 pairs of small leaflets (i.e. pinnules). These leaflets (6-12 mm long and about 1.5 mm wide) are stalkless (i.e. sessile), elongated (i.e. lanceolate) in shape, and have pointed tips (i.e. acute apices). The leaves usually fold together at night and when touched, hence the name "sensitive plant".

Flowers and fruits 

Numerous small pink or purplish coloured flowers are arranged in globular (i.e. spherical) clusters (about 12 mm across). These flower clusters are borne singly or in small groups on stalks (i.e. peduncles) 3.5-16 mm long that arise from the leaf forks (i.e. axils). Individual flowers have four tiny sepals, four inconspicuous petals (1-2.5 mm long), and eight prominent pink stamens that give the flower clusters a fluffy appearance. Flowering occurs mostly during autumn.
The fruit is an elongated and flattened pod (8-35 mm long and 3-10 mm wide) containing 3-5 one-seeded segments that break apart when the fruit is mature. These fruit have small prickles on their edges and are borne in dense clusters (usually about 10 in each cluster). The seeds (2-3.6 mm long and 1.9-2.7 mm wide) are light brown in colour, glossy in appearance, and egg-shaped in outline (i.e. ovate) but flattened (i.e. compressed).

Reproduction and dispersal 

This species reproduces by seed. These seeds usually remain in the prickly fruit segments and can float on water or become attached to animals and clothing. They may also be spread by machinery or as a contaminant of soil or agricultural produce.