Section 1. Biology and Threat - Weeds Australia

How did they become weeds?The asparagus weeds listed as WoNS wereintroduced to Australia from southern andeastern Africa in the mid to late 1800s mainly forornamental purposes such as hanging baskets andgarden plants. Indeed, A. aethiopicus is commonlyknown as basket asparagus, and the flowersand foliage of A. declinatus (bridal veil) and A.asparagoides (bridal creeper) were commonly usedin weddings. While the weedy asparagus speciesare no longer traded commercially, several speciesare still likely to be traded among home gardenersand many are still extremely common in gardens.Due to their ability to easily disperse and establishin many environments, asparagus weeds havespread from gardens into native bushland wherethey cause major negative impacts.Management note: Asparagus weedscan be difficult to control because: a)they generally have large undergroundreserves, and b) several species have fineor waxy foliage that impede herbicideuptake. After control, active restorationmay be necessary because root mats canpersist and continue to cause impacts longafter plants have been killed. Any newoutbreaks should be quickly controlled toensure extensive root mats do not develop.What do they look like?Above groundMost asparagus weeds have wiry, twining stemsthat can clamber over native vegetation. Somespecies (e.g. A. aethiopicus and A. africanus)have sharp spines along these stems. True leavesare reduced to small bracts or scales, while thebranches are modified into leaf-like structuresknown as cladodes. The cladodes (leaves) varyamong species, from very fine and needle-like (e.g.A. declinatus) to wide, thick leaf-like structures(e.g. A. asparagoides). The above ground foliageNeedle-like ‘leaves’ of A. declinatus compared to thick ‘leaves’ ofA. asparagoidesmay either dry off each summer or stay aliveyear round, depending on the species or climaticconditions. For example, the above ground foliageof A. declinatus and both forms of bridal creepergenerally dies back each summer and re-sprouts thefollowing autumn but, in cool, moist conditions,some plants may retain foliage all year.Asparagus weeds have small, white or creamcoloured flowers. They form fleshy berries that varyin colour depending on the species. Floweringand fruiting times can vary greatly with climateand location. The asparagus weeds described inthis manual are bisexual, meaning that the male(stamens) and female (pistils) parts are containedwithin each flower.Below groundAll asparagus weeds can form large root masses(rhizomatous roots), which persist year round andcan be up to 85% of the plant’s biomass. Thisallows the weeds to withstand harsh conditions,including drought and fire.Some species form ‘crowns’ at the base of thestems, with a root mass radiating out from thecrown. Other species form extensive root matsjust under the soil surface. Asparagus roots oftenhave many large tubers that act as storage organsto provide plants with nutrients and moisture (seepages 4 and 5 for root description).Management note: It is important to knowwhat is going on underground in order toplan your management and select the mosteffective control techniques.Shauna Potter3