Chlorophytum comosum

Description

Chlorophytum comosum grows to about 60 centimetres (24 in) high. It has fleshy, tuberous roots, about 5–10 cm (2–4 in) long. The long narrow leaves reach a length of 20–45 cm (8–18 in) and are around 6–25 millimetres (0.2–1.0 in) wide.

Flowers are produced in a long branched inflorescence, which can reach a length of up to 75 cm (30 in) and eventually bends downwards. Flowers initially occur in clusters of 1–6 at intervals along the stem (scape) of the inflorescence. Each cluster is at the base of a bract, which ranges from 2–8 cm (0.8–3.1 in) in length, becoming smaller towards the end of the inflorescence. Most of the flowers which are produced initially die off, so that the inflorescences are relatively sparsely flowered.

Individual flowers are greenish-white, borne on stalks (pedicels) some 4–8 mm (0.2–0.3 in) long. Each flower has six three-veined tepals which are 6–9 mm (0.2–0.4 in) long, slightly hooded or boat-shaped at their tips. The stamens consist of a pollen-producing anther about 3.5 mm (0.1 in) long with a filament about the same length or slightly longer. The central style is 3–8 mm (0.1–0.3 in) long. Seeds are produced in a capsule 3–8 mm (0.1–0.3 in) long on stalks (pedicels) which lengthen to up to 12 mm (0.5 in).

The inflorescences carry plantlets at the tips of their branches, which eventually droop and touch the soil, developing adventitious roots. The stems (scapes) of the inflorescence are called "stolons" in some sources, but this term is more correctly used for stems which do not bear flowers, and have roots at the nodes.

Taxonomy

Chlorophytum comosum was first formally described by the Swedish naturalist Carl Peter Thunberg as Anthericum comosum in the 1794 volume of Prodromus Plantarum Capensium, Thunberg's work on the plants of South Africa. It was subsequently moved to a number of different genera, including Phalangium, Caesia, Hartwegia Nees and Hollia, before receiving its current placement in Chlorophytum by Jacques in 1862.

The species has been confused with Chlorophytum capense (L.) Voss by some authors, but this is a different species.

Intra-specific variation

There are three described varieties of the species: the autonym C. comosum var. comosum has strap-shaped narrow leaves and is found along forest margins, C. comosum var. bipindense has broader, petiolate leaves with stripes on the underside and the inflorescences are 2-3 times the length of the leaves, and C. comosum var. sparsiflorum also has broader leaves that narrow to the base and usually lacks a petiole and the striping on the underside of the leaf and the inflorescences are up to two times the length of the leaves. The latter two are rain forest-dwelling taxa that had earlier been described as separate species, but botanists Axel Dalberg Poulsen and Inger Nordal reduced the taxa to varieties of C. comosum in 2005.

Delimitation of species boundaries within the genus Chlorophytum is reported to be difficult, possibly because of several evolutionary radiations into forest environments that led to morphological aspects that are too similar to reliably distinguish separate species. The evidence given to support this is the widespread distribution of most taxa in the genus and poor seed dispersal, leading to the conclusion of deeper evolutionary divergence among the taxa. The three described varieties in C. comosum could be an example of this convergent evolution of leaf shape among the forest-dwelling varieties from species of disparate origin, leading to the species C. comosum being polyphyletic, instead of the traditional view of morphological divergence among the varieties within the species with the assumption of a common origin (monophyly). The widespread C. comosum var. comosum has slender, near linear leaves that lack a petiole similar to plants found in cultivation and is only found growing at the margins of the rain forest. The two other varieties, C. comosum var. sparsiflorum and C. comosum var. bipindense, possess petioles and have broader leaves necessary for collecting more light in the shady Guineo-Congolean rain forest. A study published in 2005 used 16 morphological characters and was unable to delimit species boundaries among these three taxa, so they were relegated to varietal status. A follow-up study published in 2008 provided preliminary evidence from phylogenetic analysis of plastid and nuclear DNA sequences that established samples from disparate collections sites identified as C. comosum were polyphyletic.

Distribution

Chlorophytum comosum has a widespread native distribution in Africa, being native to six of the 10 World Geographical Scheme for Recording Plant Distributions regions of Africa (West Tropical Africa, West-Central Tropical Africa, Northeast Tropical Africa, East Tropical Africa, South Tropical Africa and Southern Africa).

Cultivation

Chlorophytum comosum is a popular houseplant. The species with all-green leaves forms only a small proportion of plants sold. More common are two variegated cultivars:

Both cultivars have gained the Royal Horticultural Society's Award of Garden Merit.

Spider plants are easy to grow, being able to thrive in a wide range of conditions. They will tolerate temperatures down to 2 °C (35 °F), but grow best at temperatures between 18 °C (65 °F) and 32 °C (90 °F). Plants can be damaged by high fluoride or boron levels.

Spider plants have also been shown to reduce indoor air pollution in the form of formaldehyde, and approximately 70 plants would neutralize formaldehyde production in a representative (ca. 160 m² [1,700 sq ft]) energy-efficient house.