silverleaf desmodium

Desmodium uncinatum
Silverleaf desmodium
Silverleaf desmodium
Silverleaf desmodium
Silverleaf desmodium leaf detail
Silverleaf desmodium
Silverleaf desmodium under leaf
Silverleaf desmodium
Silverleaf desmodium  infestation
Silverleaf desmodium flower
Silverleaf desmodium
Herb
Alternate
Compound
Pink
Purple
Variegated
Green

Usually a long-lived creeping or scrambling vine with stems up to 1.5 m long. Its stems are densely covered with hooked or curved hairs and readily adhere to skin or clothing. Its alternately arranged leaves are compound with three leaflets and are borne on stalks 2-5.5 cm long. Its leaflets (2-10 cm long) have pointed tips and their upper surfaces have a distinct silvery stripe. Its pea-shaped flowers are arranged in elongated clusters at the tips of the stems or in the upper leaf forks. These pink or purplish flowers (7-10 mm long) usually turn bluish or bluish-green as they age. Its elongated pods (1-3 cm long) are covered in hooked hairs, and readily separate into 3-10 small one-seeded segments.

Common names 
Also known as: Spanish clover, Tick clover, Velcro plant,
Family 
Fabaceae
Deciduous 
No
Flowering time 
Summer-Autumn
Native/Exotic 
Exotic
Origin 
South America
Notifiable 
No
Council declaration 
Class R – Reduce populations
Known distribution 

Naturalised in many parts of eastern Australia (i.e. in south-eastern and northern Queensland and in the coastal districts of northern and central New South Wales).

Habitat 

A weed of pastures, riparian vegetation, forets margins, open woodlands, roadsides, parks, lawns, footpaths, disturbed sites and waste areas.

Habit 

A long-lived (i.e. perennial) vine with creeping (i.e. prostrate), scrambling or semi-upright (i.e. ascending) stems up to 1.5 m long.

Impact and control methods 

Silverleaf desmodium (Desmodium uncinatum) was introduced as a fodder crop and has now become a weed of creekbanks (i.e. riparian areas), roadsides, fencelines, forest margins, disturbed sites, waste areas and plantation crops (e.g. sugarcane). It is regarded as an important environmental weed in south-eastern Queensland, and was recently ranked among the top 100 invasive plants species in the region. It is also regarded as an environmental weed in the New South Wales North Coast region.

Silverleaf desmodium (Desmodium uncinatum) spreads into forest margins and along creeks where it trails over shrubs and groundcovers, but it does not climb into trees. It has also been reported to ensnare and kill native wildlife (e.g. frogs, birds, lizards and microbats) that easily become stuck to its stems and fruit.

Stem and leaves 

The branched stems are densely covered with hooked hairs (i.e. they are pubescent), and readily adhere to skin or clothing. The lower stems often produce roots at their joints (i.e. nodes).

The alternately arranged leaves are compound with three leaflets (i.e. they are trifoliate) and are borne on stalks (i.e. petioles) 2-5.5 cm long. There is a pair of tiny bract-like structures (i.e. stipules) 3-10 mm long at the base of each leaf stalk. The relatively large leaflets (2-10 cm long and 1-6 cm wide) are egg-shaped in outline (i.e. ovate) or oval (i.e. elliptic) in shape with entire margins and pointed tips (i.e. acute or acuminate apices). Both leaf surfaces are covered with close-lying hairs (i.e. appressed pubescent). The upper surfaces of the dark green leaflets have a distinctive slivery stripe down the middle, while their undersides are paler green in colour.

Flowers and fruits 

The flowers are arranged in elongated clusters (i.e. racemes) 10-40 cm long at the tips of the stems or in the upper leaf forks (i.e. terminal or axillary racemes). Each of the small pea-shaped flowers (7-10 mm long) is borne on a stalk (i.e. pedicel) 4-10 mm long. These flowers have five pink or purplish petals (usually turning bluish or bluish-green with age) and five green sepals, which are fused together at the base. The upper petal (i.e. standard) is larger than the two side petals (i.e. wings), and the two lower petals are fused together and folded (i.e. they form a keel). Each flower also has ten stamens and an elongated ovary topped with a style and stigma. Flowering occurs mainly during spring and summer.

The small elongated pods (1-3 cm long) are usually slightly curved and covered in hooked hairs (i.e. pubescent). They are made up of 3-10 small one-seeded segments (i.e. the fruit is a lomentum). These fruit turn from green to brown in colour as they mature and the segments readily separate from each other. The small segments (3-7 mm long and 3-4 mm wide) are somewhat four-sided in shape (i.e. semi-rhomboidal). The seeds are light brown with a mixture of olive-green to cream coloured markings (i.e. they are mottled).

Reproduction and dispersal 

This species reproduces mainly by seed, but its creeping stems may produce roots when they come into contact with moist soil.

The fruit separate into one-seeded segments, that readily become attached to animals, clothing and vehicles. Seeds may also be dispersed by water and in contaminated agricultural produce.

Similar species 

Silverleaf desmodium (Desmodium uncinatum) is very similar to creeping beggarweed (Desmodium incanum ) and greenleaf desmodium (Desmodium intortum ), and relatively similar to the native carpon desmodium (Desmodium heterocarpon) and Florida beggarweed (Desmodium tortuosum ). These species can be distinguished by the following differences:

■silverleaf desmodium (Desmodium uncinatum) is usually a creeping or scrambling plant less than 1 m tall. Its leaves have a conspicuous silvery-coloured stripe on their upper surfaces. The leaflets have pointed tips (i.e. acute or acuminate apices) and are hairy (i.e. pubescent) on both surfaces.

■creeping beggarweed (Desmodium incanum ) is usually a creeping or scrambling plant less than 1 m tall. Its leaves are uniformly green or have an inconspicuous silvery-coloured stripe on their upper surfaces. The leaflets often have rounded tips (i.e. obtuse apices) and their upper surfaces are only sparsely hairy (i.e. puberulent).

■greenleaf desmodium (Desmodium intortum ) is usually a creeping or scrambling plant less than 1 m tall. Its leaves are uniformly green or sometimes have some small reddish-brown markings on their upper surfaces. The leaflets have pointed tips (i.e. acute or acuminate apices) and are hairy (i.e. pubescent) on both surfaces.

■carpon desmodium (Desmodium heterocarpon) is a low-growing shrubby plant less than 1 m tall. Its leaves have pale green or yellowish-green central markings on their upper surfaces. The leaflets often have rounded tips (i.e. obtuse apices) and their upper surfaces are hairless (i.e. glabrous) or sparsely hairy (i.e. puberulent).

■Florida beggarweed (Desmodium tortuosum ) is an upright shrubby plant growing up to 2 m tall. Its leaves are uniformly green or sometimes have some small reddish-brown markings on their upper surfaces. The leaflets usually have pointed or rounded tips (i.e. acute or obtuse apices) and are hairy (i.e. pubescent) on both surfaces.