Asparagus

Herbs, shrubs, or vines, perennial, from rhizomes, usually with fusiform tubers, often with fernlike appearance. Stems photosynthetic, erect, spreading or climbing, branched; cladophylls solitary or fasciculate, in nodes of reduced, scarious leaves. Leaves small, scale-like, membranous, or sometimes spiny with hardened base, subtending cladophylls. Inflorescences axillary or terminal, racemose, or umbellate, paired or solitary; racemes short. Flowers bisexual or unisexual; perianth greenish, white, or yellowish, campanulate to rotate; tepals 6, distinct or shortly connate basally, equal; stamens 6, distinct, equal; anthers versatile, 2-locular, dehiscence introrse; ovary superior, 3-locular, septal nectaries present; style 3-branched distally; pedicel with conspicuous joint. Fruits baccate, red or purplish black, globose, often with tepals persisting at base. Seeds 1–6, black, globose to angular. x = 10.

Distribution

Europe, Asia, Africa, some widely introduced, expected elsewhere.

Discussion

Species 170–300 (4 in the flora).

Asparagus is a moderately important horticultural genus, with one species commonly grown for its edible young shoots and a number of others grown ornamentally. The genus is treated here in a broad sense (K. Kubitzki and P. J. Rudall 1998; W. S. Judd 2001) and encompasses species that have been segregated in several genera (A. L. Takhtajan 1997; S. T. Malcomber and Sebsebe D. 1993). Embryological features (P. J. Rudall et al. 1998) and DNA-based analyses (M. W. Chase et al. 1996; M. F. Fay et al. 2000; P. J. Rudall et al. 1997) support the monophyly of Asparagus and the Asparagaceae.

Asparagus virgatus Baker has been collected once as a garden escape in East Baton Rouge Parish, Louisiana, but it is probably not truly naturalized in the flora. Asparagus falcatus Linnaeus occasionally persists after cultivation in the Miami–Dade County area of southern Florida (W. S. Judd 2001).

Selected References

Jessop, J. P. 1966. The genus Asparagus in southern Africa. Bothalia 9: 31–96.

Malcomber, S. T. and Sebsebe D. 1993. The status of Protasparagus and Myrsiphyllum in the Asparagaceae. Kew Bull. 48: 63–78.

Sovetts, C. and R. Sattler. 1986. Phylloclade development in the Asparagaceae: An example of homoeosis. Bot. J. Linn. Soc. 94: 327–371.

Lower Taxa

Asparagus aethiopicus, Asparagus asparagoides, Asparagus officinalis, Asparagus setaceus

Key

1	Plants erect; some flowers unisexual.	Asparagus officinalis
1	Plants scrambling, twining, or arching; all flowers bisexual.	> 2
2	Cladophylls solitary at each node, broadly lanceolate to ovate, with 20–24 veins.	Asparagus asparagoides
2	Cladophylls in fascicles of 3–20 per node, linear or filiform, with single vein.	> 3
3	Cladophylls filiform; pedicels 1–3 mm; inflorescences 1–4-flowered terminal umbels; berries purplish black.	Asparagus setaceus
3	Cladophylls flattened; pedicels 5–8 mm; inflorescences 5–9(–17)-flowered axillary racemes; berries red.	Asparagus aethiopicus