Stellaria Abortiva

''Stellaria apetala'', commonly known as lesser chickweed, is an annual herbaceous plant in the flowering plant family Caryophyllaceae. It is native to Europe and is an introduced species in North America.

Taxonomy

''Stellaria apetala'' forms part of a complex that also includes '' S. media'' and '' S. neglecta''.
It was first described by Ucria in 1796 as ''Alsine petala''. In 1828, Du Mortier, describing a form found in Belgium, applied the name ''Alsine pallida'', which Piré (1863) transferred to the genus ''Stellaria''.

The taxonomic status of ''Stellaria apetala'' (Dumort.) Piré has been confused. Dandy (1958) and Clapham, Tutin and Warburg (1962) adopted the name ''Stellaria pallida'' but while Clapham et al. treated ''S. apetala'' Ucria as a synonym, Dandy considered this to be a synonym of ''S. media'' L., as also did Chater and Heywood. Whitehead and Sinha, having failed to locate any specimens matching the description in the ''Flora Europaea'', concluded that ''S. apetala'' Ucria or ''S. apetala'' auct. could be regarded as synonyms of ''S. pallida'' (Dumort.) Piré. ''Stellaria pallida'' is now considered as a junior synonym of ''Stellaria apetala''.

Description

''Stellaria apetala'' is a much-branched herb, generally yellowish-green in colour. The stems are prostrate, usually 10–20 cm long, though some can reach 40 cm, and glabrous, with a single row of hairs between each pair of nodes. Leaves are pale-green and ovate, up to 1.5 cm long and usually less than 0.7 cm broad; proximal leaves have a short stalk, distal leaves are sessile.

The flowers are borne in terminal inflorescences of between 3 and 6 cymes. Flowers are small, 2–3 mm in diameter, and never open widely. There are four or five green sepals, lanceolate and 2–3.5 mm long. Petals are usually absent, or, if present, are minute. There are usually between one and three stamens, sometimes none, with grey-violet anthers, and three styles.

The numerous seeds are pale yellowish-brown, occasionally darker, 0.6–0.8 mm in diameter, with prominent small, blunt tubercles.

''Stellaria apetala'' is self-pollinating and, because the flowers do not open widely, is often cleistogamous.

Distribution and habitat

''Stellaria apetala'' has a widespread, though local, distribution across Europe, from southern Spain and the Mediterranean islands to Lapland, and from the British Isles to Ukraine. In North America it is found as an introduced species from Ontario, Canada, to Mexico and throughout the United States, from the east coast (Virginia, North and South Carolina, and Florida) to the west coast (California and Washington).

''Stellaria apetala'' is usually found on coastal sand dunes, in sandy waste places, or on cultivated sandy soils. In Europe it is often found growing under the shade of Scots Pine in woodland on light glacial sands.

References

{{Taxonbar, from1=Q11085761, from2=Q160076

apetala