Mimosa casta
(graceful mimosa)

M. casta is a fast-growing perennial vine that is included in the Global Compendium of Weeds (Randall, 2012). The ability of this species to tolerate a wide range of habitats including disturbed areas, roadsides, pastures, semi-waterlogged areas, as well as natural forests means that it has the potential to spread much further than it has to date. Additionally, the species is able to climb over other species and supports itself on other plants by means of spines which are borne along the length of its stems and petioles, forming a dense cover and presumably competing for resources (i.e., sunlight) with native species. In Puerto Rico, this species is classified as a “noxious weed” (USDA-ARS, 2012).

The native distribution range of this species includes the Lesser Antilles (including Barbados, Dominica, Grenada, Guadeloupe, Martinique, St. Lucia, St. Vincent, and Trinidad and Tobago) and Latin America from Panamá to Brazil. M. casta is reported as an “exotic species” in Mexico, French Guyana, and Puerto Rico where it is common at lower and middle elevations (Acevedo-Rodríguez, 2005; Acevedo-Rodríguez and Strong, 2012).

The risk of introduction of M. casta is high. The presence of spiny fruits means that the species can be easily dispersed by humans and animals in mud or by adhering to fur, clothing, and vehicles. In additions, seeds may remain dormant and viable for several years waiting for suitable conditions to germinate.

M. casta is a rapidly growing perennial, woody vine and it can be found along roadsides, disturbed areas, secondary forest, pastures, riverbanks, dry coastal forest and semi-waterlogged areas. In Puerto Rico this species has been recorded on roadsides and in pastures at lower and middle elevations (Acevedo-Rodríguez, 2005).

Genetics

There are no specific genetic studies based on M. casta. However, studies for other Mimosa species suggest that within this genus the number of chromosomes may vary from 22-56 (2n) (Dahmer et al., 2011). 

Reproductive Biology

The principal mechanism of reproduction in M. casta is the production of seeds. Flowers in this species are arranged in an inflorescence. The inflorescence is a head of small flowers that typically bloom for one day. Flowers are visited by insects, and recorded visitors include members of Hymenoptera, Diptera and Coleoptera.

Based on the high pollen/ovule ratio characteristic of the genus Mimosa, a xenogamous breeding system is expected. 

Physiology and Phenology

In Puerto Rico, this species has been collected in flower and fruit in January and February. 

Longevity

M. casta is a perennial vine. Plants grow rapidly and produce abundant stems. Flowering starts about 3-6 months after germination, depending on resource availability. 

Associations

In the Lesser Antilles, M. casta is widespread in moist open and semi-open areas, often degraded, at lower and middle elevations including pastures, grassland with a scattered shrub layer, and coastal forests (Graveson, 2011). In Puerto Rico, this species is a component of the weed community in roadsides, disturbed areas, and pastures in lower and middle elevations (Acevedo-Rodríguez, 2005). As with many Mimosa species, M. casta is a nitrogen-fixing legume and possesses root nodules housing Rhizobium bacteria.

Animal feed, fodder, forage

• Forage
• Invertebrate food

Fuels

• Fuelwood

Human food and beverage

• Honey/honey flora

Medicinal, pharmaceutical

• Source of medicine/pharmaceutical
• Traditional/folklore

M. casta is similar in habit to Mimosa ceratonia, but can be distinguished because the leaves are quite different. In M. casta, leaves are arranged in a single pair of pinnae with 3-4 pairs of leaflets, whereas M. ceratonia has 3-8 pairs of leaflets. M. casta is very closely related to M. schankioides, which has a similar calyx, but less numerous and larger leaflets (Barneby, 1991).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

In Puerto Rico, this species is classified as a noxious weed and the introduction into Puerto Rico at any plant stage is prohibited (USDA-ARS, 2012).

A study performed in Puerto Rico evaluating the potential use of small ruminants (i.e., goats) to control the growth of invasive plant species including M. casta, has showed that goats consumed basal leaves of M. casta but did not damage the branches or stems. There was, however, 90% reduction on this species in areas subject to goats-browsing. Browsed plants did not recover, but new plants originated from existing seeds in the pasture (Muir, 2009). This study demonstrates that management strategies for the effective control of this invasive species should include active management of plants at different life-cycle stages.

24/10/12 Original text by:

Julissa Rojas-Sandoval, Department of Botany-Smithsonian NMNH, Washington DC, USA

Pedro Acevedo-Rodríguez, Department of Botany-Smithsonian NMNH, Washington DC, USA