Asparagus aethiopicus -- California

It is invasive and naturalized in Florida, Hawaii, Australia and also found in South America.

This species is currently naturalized in California and is also naturalized in eastern Australia in New South Wales, and Spain, where the climate matches California

Yes it is noted as being invasive (spreading and causing harm) in Australia, Florida and Hawaii.

Noted as being invasive and in Australia, NSW, where the climate matches California. It is also found in Coastal Southern California in natural areas. In coastal Southern California most current locations are found near the wildland urban interface.

Asparagus asparagoides is invasive in California. Other Asparagus species are also invasive and/or naturalized in Australia.

Most of the locations for Asparagus aethiopicus are in more tropical areas, such as the southeastern US, Hawaii, Central America, and north eastern Australia (Queensland).

From the NSW Weed Wise website: "Ground asparagus forms dense blankets of growth above ground and a profusion of roots and tubers below ground which suppresses other ground flora and reduces available soil moisture and nutrients."
The Weeds of Australia website says "Ground asparagus (Asparagus aethiopicus 'Sprengeri') forms a thick mat of tuberous roots and grows particularly well in shaded areas and in sandy soils." "The dense growth of this species may form impenetrable thickets that smother native understorey plants and inhibit their regeneration, thereby transforming the ground layer of native plant communities."

This plant does not contain a lot of leaves and does not create a lot of fuel. The branches are thin, the leaves are small and long. It is also a perennial of mostly shady locations, often near the coast, and does not dry out completely to create highly flammable fuels with low fuel moisture.

This species appears only toxic to dogs and cats. If it is toxic to livestock, it does not appear to invade grasslands and the likelihood is that few livestock would eat it. It is not likely that livestock eat this species, although one source (Lusigi et. al 1984) show that this species can be a minor (20% or less) component of goat forage in the wet season in Kenya.

This species spreads and can form mats along the ground and can suppress other plants from growing or establishing. It is difficult to determine if these mats suppress the spread of animals. The plant is low growing or grows inside other plants using them as support so it is unlikely they would slow the movement of livestock or humans. It is unknown if it could inhibit movements of smaller animals.

From the NSW Weed Wise website: "Ground asparagus forms dense blankets of growth above ground and a profusion of roots and tubers below ground which suppresses other ground flora and reduces available soil moisture and nutrients."

From Asparagus Weeds Management Manual "Asparagus aethiopicus creates vigorous thickets of foliage that forms dense spiny mats. It can quickly invade disturbed sites in open sun or partial shade. Plants can form monocultures that smother and displace native herbs and shrubs, and can form impenetrable root mats below the ground that may impede the growth of native seedlings. The above ground biomass can dominate the native ground and shrub layer."

Main mode of reproduction is by seeds and to a lesser extent by vegetative spread. It can spread if rhizomes are transported, such as by gardeners or infected poorly processed compost or following disturbance that separates rhizomes from the plant. The plant can also be propagated by dividing the central crowns (rhizomes), but the underground tubers are storage organs are do not promote vegetative spread. Most spread is not by vegetative plant parts, but by the spread of seeds.

It does not appear the spread of plant fragments is a common method of dispersal. "Spread is primarily by seeds" -Asparagus Weed Management Manual.

The main method of reproduction is seed.

"Up to 600 mature fruit were observed on a single plant at one time, and while most fruit was observed on bushes in May and June, ripe fruit was observed in every month of the year."
Plants can also produce 3 seeds per fruit and if there are 2-3 seeds per fruit on some plants there will be over 1,000 seeds per plant.

Germination was greater than 30% after 30 days of collecting fruits in both February and April.

Plants mature within 1.5 - 2 years (see source page 12)

"Up to 600 mature fruit were observed on a single plant at one time, and while most fruit was observed on bushes in May and June, ripe fruit was observed in every month of the year."

Several sources suggest birds are one dispersal agent, and move seeds "far from the main plant." Presumably birds ingest the fruits and disperse the seeds long distances.

The main way this species reproduces is through dispersal of seeds in the fruits. Birds and other wildlife are believed to be primary dispersers. The fruits are round and heavy and cannot be dispersed by wind; they could roll down hill in some unique situations. Available sources do not mention if the fruits float and emphasize dispersal by wildlife.

No, the main dispersal for this species is seeds by birds and by plant parts (crown divisions, rhizomes) intentionally by gardeners, not by contaminated seed, equipment vehicles or clothing. Fruits and plant propagules, such as rhizomes would be spread intentionally by gardeners, or in infected compost or soil, but would not be frequent.