Dolichos Pea

Dipogon lignosus (L.) Verdc.

Family: Fabaceae.

Names:

Dipogon
Lignosus because it is woody.
Dolichos Pea because it was previously incorrectly identified as Dolichos lablab and it is a member of the pea family.

Other Names:

Australian Pea
Chook house Vine refers to its common use in covering backyard poultry houses.
Common Dolichos
Dunny Creeper refers to its common use in covering outside toilets, where Dunny is Australian slang for toilet.
Lavatory Creeper refers to its common use in covering outside toilets or lavatories
Okie Bean
Purple Dolichos

Summary:

Dolichos Pea is a perennial, robust climbing vine with alternate leaves divided into 3 broadly triangular leaflets each 2-7 cm long. It has many clusters of large pea flowers that are white or pink to purple and 8-15 mm long. The flat seed pod is 2-4.5 cm long and 7-9 mm wide. It has perennial, spreading, underground rhizomes.
Originally from South Africa it is commonly grown in gardens and has become a serious weed in disturbed bushland areas especially near the coast. It flowers in spring and early summer.

Description:

Cotyledons:

Two.

Leaves:

Alternate.
3 leaflets, the central leaflet on a much longer stalk than side leaflets which are opposite each other.
Stipules - Narrowly egg shaped stipules at the base of the petiole but not joined to the petiole. Awl shaped stipules(stipellae), 2-7 mm long at the base of the leaflets.
Petiole - Long.
Blade - Bright green, diamond to broadly egg shaped, 20-69 mm long x 13-65 mm wide, widest near the base, fine tapering tip, smooth edges. Soft texture. Upper surface darker than the lower surface. Sparse low lying hairs on the veins and edges. The central leaflet is slightly longer than the side leaflets.

Stems:

Hairless or sparsely hairy, long and twining. Initially thin, becoming woody and wiry with age, Woody at the base. Butts of old plants can be up to 100 mm diameter. The stems my form roots where they contact the ground. The vines may climb to on trees up to 4 metres high.

Flower head:

Racemes on stalks(peduncles) from the leaf axils, up to 250 mm long.
Flowers stalks(pedicels) often bent back. Bracts and bracteoles narrowly egg shaped with tiny hairs.

Flowers:

White, pink or purple and up to 10-15 mm long and pea type. Self fertile.
Ovary - Style hairy towards the top.
Calyx - 2 lipped, 3-4 mm long, Hairs on the edges of the lobes. Upper lip with 2 rounded lobes. Lower lip with 3 triangular lobes.
Petals - White, pink or purple. Standard 8-15 mm long. Keel incurved, acute tipped, purple tipped.
Stamens - 10 with 9 joined in an open sheath with 1 free stamen.
Anthers - Uniform.

Fruit:

Stalkless, green, slightly curved, almost flat pod, 23-45 mm long x 7-9 mm wide, narrowly oblong in outline, tapered at the base and tip, occasionally slightly constricted between the seeds. Edges thickened. Hairless. Opens in late spring to summer to explosively release the seeds. 3-6 seeds per pod.

Seeds:

Brown to black with a white 'eye', flattened, almost circular in outline, about 4.5 mm diameter. Seed stalk(funicle) flattened and expanded at the seed into a thin appendage(aril). Large amounts of seed are produced and they remain viable in the soil for many years.

Roots:

Taproot occasionally branched and may be several metres long with finer feeder roots. Perennial rhizome. There may be roots on the stems where they touch the ground.

Key Characters:

Perennial. White, pink or purple pea type flowers. Long twining stems. Leaves 3-foliate, imparipinnate, terminating in a leaflet. Leaflets entire. Stipules not adnate to the petiole. Stipellae present. Style hairy towards the apex. Stamens diadelphous (in an open sheath with 1 free stamen). Anthers uniform. Bracteoles narrowly ovate, ciliate.

Biology:

Life cycle:

Perennial. Seeds germinate in autumn and germination is prolific after fire or denudation. The seedling forms a woody base within six months. The top growth dies off each summer. The next autumn the rootstock sends up stronger shoots that climb over other vegetation. This is repeated annually and it flowers in spring to summer of its second or third year of growth. The seed is ejected explosively from the pods in summer and may be thrown several metres. Stems may form roots and new daughter plants where they contact the soil. The parent may live for more than 10 years.

Physiology:

Tolerates drought, wind, frost, salt spray.
Fixes atmospheric nitrogen.

Reproduction:

By seed, rhizomes, suckers and stem layering.

Flowering times:

September to November in Perth.
Spring in WA.
September to January with a flush in September to October in SE Australia.

Seed Biology and Germination:

Seed may remain dormant in the soil for many years.
Large plants can produce thousands of seeds annually.
Seed can remain dormant in the soil for several years.
Disturbance or fire usually stimulates germination.

Vegetative Propagules:

Suckers and stem layering. Regrows from underground tubers each year and when stems are damaged.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Spread short distances by explosive release of seed from the pod and forming roots where stems contact the soil. It can move 3-5 m per year by these methods. Medium range dispersal by birds, movement in water flows, earth moving and dumping of garden waste and long range dispersal by intentional planting. It is commonly sold at fetes and markets and the white form is sold in nurseries.
It produces a large amount of seed which has a good survival rate.

Origin and History:

South Africa.
Introduced as a garden ornamental and commonly used to cover outside toilets, poultry houses and backyards sheds.

Distribution:

NSW, QLD, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Growth is most vigorous in full sun situations but it will establish in shaded areas.

Climate:

Temperate. Mediterranean.

Soil:

Prefers free draining sandy and loam soils but will grow on heavy soils and tolerates a wide range of soil types.

Plant Associations:

Dry coastal vegetation, heathland, heathy woodland, woodlands, dry coastal forest, woodland, riparian species, warm temperate rainforest and dune plants

Significance:

Beneficial:

Food. Ornamental. Often cultivated in the South West of WA.

Detrimental:

Weed of gardens, roadsides, bushland and disturbed areas.
Naturalised in many coastal areas where it takes over disturbed bushland.
Forms dense mats that smothers low growing vegetation and climbs trees and shrubs often breaking branches with its weight.
Particularly likes growing up guy wires on telephone and electricity poles where it causes interference with supplies.
It increases the soil nitrogen levels which affects the persistence of some species.

Toxicity:

Not recorded as toxic.

Legislation:

None.

Management and Control:

Little work has been done on the management and control of Dolichos Pea. The following are best bets based on anecdotes and experience with similar plants.
Fire provides some control but there is usually a mass germination of seedlings after fire and rootstocks will reshoot after moderate intensity fires.

Thresholds:

Rarely invades crops or pastures.

Eradication strategies:

Manual removal is difficult because of the perennial nature of the plant, its rhizomes which may re sprout if damaged, the quantity of seed that has been set before control and its dormancy. In addition many infestations are intermingled with companion species and trees making access and effective removal of roots difficult.
Small plants can be hand pulled but larger plants tend to break off and regrow.
Cultivation with disc implements over the summer and repeated when seedlings appear for a few years should be effective in open situations.
Fencing degraded areas and grazing heavily with sheep for several years is also expected to be effective.
Slashing is not likely to be very practical or effective.
Hot fires can kill plants but reshooting often occurs after moderate fires. A massive germination of seed often occurs after burning.
Seed production can be reduced by cutting the stems near ground level in spring before flowering and then repeating this in about 4 weeks to control regrowth.
Herbicide treatments are likely to be useful to reduce and weaken the infestation to levels that can be controlled by manual removal.
1 L/ha Grazon® plus 0.25% Pulse® or 10 mL of Grazon® plus 25 mL Pulse® in 10 L of water and spraying until run off in August provides reasonably selective control in bushland. (Cutting the vines on trees at 1.5 m above ground level and spraying only the lower section improves control but is labour intensive). If possible, follow this with burning and soil disturbance in autumn to encourage seed germination and re-sprouting and repeat the spray treatment in spring. Higher rates of Grazon® will damage native bush. 100 mL glyphosate(450g/L) plus 25 mL Pulse® in 10 L water can also be used but is less effective and less selective than the Grazon treatment.
In small areas the stems can be cut just above ground level and then painted with undiluted glyphosate. This provides good control of the parent plants and rhizomes but follow up treatments for a number of years is required to control the seedlings. The cut stems may be sprayed with a 1% glyphosate mixture to control regrowth from stems and any seedlings.

Herbicide resistance:

None reported.

Biological Control:

Related plants:

Plants of similar appearance:

It is often incorrectly identified as Dolichos lablab and was previously confused with Lablab purpureus.
Clematis (Clematis linearifolia, Clematis pubescens) are native climbing vines and have cream to white, 5-petalled flowers forming a feathery head of small fruitlets and opposite leaves with 3 leaflets that have long stalks (petiolules) of similar length.
Kudzu or Japanese Arrowroot (Pueraria montana var. lobata = Dolichos lobatus) has similar flowers and is a major invasive weed of the USA and is now in NSW and QLD.
Kennedia species have a hairless style and red to mauve and yellow flowers and pithy partitions between the seeds in the pod.
Wild Sarsaparilla (Hardenbergia comptoniana) has a hairless style and blue to purple (rarely white) pea type flowers with a yellow green “eye” on its standard petal.
Peas and various legumes can look similar when young.

References:

Blood, K. (2001). Environmental weeds: a field guide for SE Australia. (CH Jerram & Associates, Australia). P106-107. Photos.

Hussey, B.M.J., Keighery, G.J., Cousens, R.D., Dodd, J. and Lloyd, S.G. (1997). Western Weeds. A guide to the weeds of Western Australia. (Plant Protection Society of Western Australia, Perth, Western Australia). P150. Photo.

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #452.1.

Marchant, N.G., Wheeler, J.R., Rye, B.L., Bennett, E.M., Lander, N.S. and Macfarlane, T.D. (1987). Flora of the Perth Region. (Western Australian Herbarium, Department of Agriculture, Western Australia). P255.

Moore, J.H. and Wheeler, J.R. (2002). Southern Weeds and their Control. Photos.

Muyt, A. (2001). Bush Invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South East Australia. (R.G and F.J. Richardson, Australia). P136-137. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.