Synonyms: Myrsiphyllum APNI*
Protasparagus APNI*
Description: Shrubs or vines with prickly or smooth stems that persist or are replaced annually; roots fibrous, sometimes tuberous.
Leaves alternate, reduced to scales and subtending leaf-like cladodes; stipules absent.
Inflorescence axillary or terminal, flowers solitary, clustered or in umbels or panicles. Flowers actinomorphic, 3-merous, pedunculate (pedicels jointed), bisexual or unisexual and then plants dioecious. Tepals 6, in 2 whorls, free or fused basally. Stamens 6; filaments free or fused basally; anthers basifixed, 2-locular, introrse, dehiscing by longitudinal slits. Ovary superior, 3-locular; ovules usually 2–12 per loculus; style short; stigma 3-lobed or unlobed.
Fruit a berry; seeds 1–numerous, usually black, shining.
Distribution and occurrence: About 170 species worldwide (mainly in Africa and Eurasia), about 12 spp in Australia (1 sp native, 11 spp naturalized or liable to become naturalized), all mainland States.
A. officinalis is the well-known edible asparagus. Various other species are cultivated as ornamentals, and all are potentially weedy as garden escapes or via seed distributed by birds (berries are mostly reddish when mature). A. retrofractus is naturalized in SE Qld and is probably naturalized on the North Coast and Central Coast of NSW. It seems to have been confused with the cultivated A. macowanii, which is a separate species not known to be weedy (but all have the potential to become weedy). The naturalized species are often serious weeds - see http://www.weeds.org.au/WoNS/asparagusweeds/ for useful information and other links for weedy species. Besides the species covered here, A. macowanii is widely cultivated and may be naturalized on the Central Coast. In terms of underground structures, all species have extensive root masses with short or long rhizomes and fibrous roots, in some cases also with swollen tuberous root structures that store water; fragments of rhizome germinate readily. Species can be classified as (1) crown-forming (with a solid central underground crown and more or less fibrous or slightly succulent rhizomes and roots radiating from it; in some cases also with numerous tuberous-looking roots) or (2) mat-forming (without a central crown but with an extensive spreading network of fibrous rhizomes and roots and many tubers). Of the species found in NSW, only A. asparagoides is mat-forming. Control is different for crown-forming and mat-forming species - see weeds websites for details. It is useful to record this feature when collecting a specimen for identification.
Text by GJ Harden (1993); edited KL Wilson (Aug 2011; Mar 2013, Jan 2014; Oct 2014)
Taxon concept: Now treated as one genus, Asparagus; previously Protasparagus and Myrsiphyllum were regarded as separate genera.
Taxa not yet included in identification key
Asparagus retrofractus
| | Key to the species | |
| 1 | Cladodes terete or filiform, c. 0.5 mm in diameter | 2 |
| Cladodes flattened, usually >1 mm wide | 6 |
| 2 | Cladodes usually 3–6 in each axil, 5–25 mm long[; stems erect, not spiny] | 3 |
| Cladodes mostly 6–40 in each axil, 4–15 mm long
Back to 1 | 4 |
| 3 | Longest cladodes usually 15–20(-25) mm long; flowers unisexual | Asparagus officinalis |
| Longest cladodes usually <15 mm long; flowers bisexual
Back to 2 | Asparagus virgatus |
| 4 | Stems erect but not climbing, small spines only on lower parts of stems; cladodes numerous (to c. 50) in each axil and forming dense more or less globose clusters, 8–15 mm long | Asparagus macowanii |
| Stems climbing, spiny; cladodes 3–15 in sparse clusters in each axil, 4–12 mm long
Back to 2 | 5 |
| 5 | Cladodes 4–7 mm long, stems and cladodes all in 1 plane; spines usually <5 mm long | Asparagus plumosus |
| Cladodes 7–12 mm long, stems and cladodes not in 1 plane; spines on older stems >5 mm long
Back to 4 | Asparagus africanus |
| 6 | Cladodes >5 mm wide, more or less ovate; plants mat-forming underground with numerous tubers | Asparagus asparagoides |
| Cladodes 1–4 mm wide, more or less linear to narrow-lanceolate; plants with an underground crown and fibrous roots (occasionally some tuberous)
Back to 1 | 7 |
| 7 | Cladodes 1–1.5 mm wide, 5–15 mm long, 3 in each axil; tepals shortly united; aerial stems more or less annual | Asparagus scandens |
| Cladodes 2–4 mm wide, 15–90 mm long, 2–5 in each axil; tepals free; aerial stems perennial
Back to 6 | 8 |
| 8 | Cladodes 15–25 mm long, 2–3 mm wide, more or less straight | Asparagus aethiopicus |
| Cladodes 35–90 mm long, 3–4 mm wide, usually slightly falcate
Back to 7 | Asparagus falcatus |
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